A DN is a small one design iceboat. It is a single seater
roughly 12ft long and 8ft wide. By far the most popular
iceboat in the world, with around 150-200 boats participating
in the World Championships each year.

You can get more info, some pictures, and links to other site here:
IDNIYRA website www.idniyra.org

583

Posted by: A. Brown on December 01, 2001 at 14:07:08:

Perhaps there could be another forum here for those of us that do not race, but are enthusiastic recreational iceboaters. It would be nice to have a forum for options that are not necessarily race legal.

With a little bit more flexibility, you might even see your membership improve.

586

Posted by: Ken Smith on December 02, 2001 at 00:51:58:

In Reply to: Perhaps.... posted by A. Brown on December 01, 2001 at 14:07:08:

A. Brown:

There are many items and discussions about not-class legal things on this board, and it is the most active board on ICE I've seen. If you enjoy sailing, can you deny that you've seen if you are faster than the others on your lake? If so, you are racing. After investing the time and effort to build something close to a DN, the little differences should be understood so that when you are done you have a boat which IS or can be made into a DN, so you can race with the best as well as the locals. Everyone loves to see entheuastic sailors, because if they are good and travel to sail, soon they will be racing.

Whenever someone asks about something which is not "DN class legal" you can bet a reply will point this out. This is neither criticism nor judgement about the proposal, just information. Take it or leave it. I built a hull with some carbon fiber reinforcement once, and decided to race. I had to deal with the carbon to participate. If I had known, I would have used something else.

Build what you want. But if your DN is not class legal, you will not be able to participate in a big race.

Besides, it is hard to improve on these simple, elegant, highly portable little boats. You can cut some costs with sails and the like, but they can easily be upgraded. Making the boat longer, wider deeper or round will almost certainly make it harder to load on a vehicle, heavier, harder to sail, or unable to sail in conditions adequate for a DN. They are already well evolved.

Ken Smith
DN4137

589

Posted by: mark kiefer on December 02, 2001 at 19:47:43:

In Reply to: Perhaps.... posted by A. Brown on December 01, 2001 at 14:07:08:

My friend Al sails out of central Minnesota on a "gambit", sorry Lloyd, that he has maybe 60 total dollars in. In terms of fun per dollar, it's hard to beat his ride. You can build a sail out of tyvek house wrap for about 12 bucks, he built his out of "free" 1.5 oz nylon, and goes 35-40, or in the alternative you can spend two weeks (if you can sew 6 oz, most machines won't suffer that job silently), the 170 bucks and still go 35 - 40, on clear ice if it's blowin, read ZERO GAIN over house wrap.

As for me, I like going as fast as I can in a DN, if I want to go any faster, I'll use the car.

The primary purpose of this forum is to engage a dialog where faster, more experienced sailors give their experiences to enable sailors (choppers like us) to sail faster and safer. Fast is fun, faster is funner.

If you get advice from the best in the world, (and some of that was posted on this thread earlier, by "Jane") and don't like the advice, don't blame the messenger.

It' real simple, any dn (flavor) iceboater can get a brand new sail with battens for 600 clams and a great used one for a third of that, they last recreationally forever(literally), and run laps around almost any other sail run up a similar mast. If you think you can save money or time, or get better performance by doing it yourself, you're nutz, go buy a couple yards of tyvek, and do a "but the wind is free", on the cheap program, we'll understand.

think ice

4695

History and sources

498

Posted by: Paul Goodwin on August 02, 2000 at 06:56:26:

In Reply to: Plans wanted posted by Doug Stearns on July 27, 2000 at 17:31:08:

The obvious place to look for the Gougeon plans is to place
a call to the Gougeon Brothers, Inc. I think they have quit
selling their plans, but I could be mistaken. [Not available in 2004]

The current plans available from the IDNIYRA are very similar
to the Gougeon plans, and take many of the construction ideas
directly from the Gougeons. I believe the IDNIYRA plans are
more versatile, especially in terms of their suitability to
a wide range of sailors.

If you do get a set of Gougeon plans, definitely move the
#4 bulkhead (front of cockpit) forward to make the cockpit
maximum length. This will allow a taller sailor to get
down in the cockpit to reduce wind resistance.

As an alternative (or in addition) to scale plans, I offer
a set of full-size templates for the hull. This can save
a lot of time and effort by eliminating the lofting stage
(converting from scale to full size measurements). Feel
free to email if you need more info.

549

Posted by: Paul Goodwin on February 09, 2001 at 07:49:27:

In Reply to: Re: Plans wanted posted by Tim Heine on February 05, 2001 at 19:15:41:

Plans for the DN iceboat are available from the IDNYRA Treasurer for $15. To get a set, print the membership application form from the IDNIYRA NA website and check the section on plans. Send the form and a check to the Treasurer (address is on the form).

While your at it, why not join the IDNIYRA???

Here is a direct link to the membership application form: [corrected 2004]

IDNIYRA membership form: http://www.sailingsource.com/ice/member.htm
OR through the website: www.IDNIYRA.org

811

Posted by: BILL GRENIER on October 21, 2003 at 18:07:30:

In Reply to: Re: Plans wanted posted by Paul Goodwin on August 02, 2000 at 06:56:26:

I got some plans from you a few years ago, but was a little intimidated by the hardware involved in making a DN ice boat, I already have a aluminum mast and sail from an old sailboat which I hope to use, Is there anyone who supplies the hardware for the boat? I would like to finally get started.

812

Posted by: Geoff Sobering on October 22, 2003 at 10:15:49:

In Reply to: Re. hardware posted by BILL GRENIER on October 21, 2003 at 18:07:30:

Sarns Hardware (http://www.sarnshardware.com/) is the tradidion supplier of DN hardware (basically the designs shown in the official plans). Steve Duhamel (Northwind Iceboats) at 781-826-8004 has a nice collection of European parts; he is a frequent poster on the Yahoo! Iceboating group (http://groups.yahoo.com/group/IceBoating/).

There are any number of other suppliers (some listed at the top of the Bulletin Board). Also, the "Vendors" section of the Iceboat.org page may be helpful (http://iceboat.org/cool_links.htm).

Good luck with your boat!

Cheers,

Geoff S.

P.S. You may want to reconsider the use of a soft-water mast/sail combination. It will probably work, but it will likely be 1) way too big, and 2) way too full. The DN is considered a fairly overpowered iceboat (for it's size); it has a sail of about 70 sq ft. For comparison, a Laser softwater boat has a 75 sq ft sail.

Buying

Used boats and repairs

396

Posted by: Ken Smith on July 27, 1999 at 07:27:03:

In Reply to: Restoring an old DN iceboat. NEED HELP!!! posted by Oliver Rush (sail # 3339) on June 19, 1999 at 19:47:36:

Sources for material:

http://www.paw.com/sail/ice/

Click the suplier list for dealers and other information.

The following is a checklist to get an old boat on the ice. It may or may not be complete.

Rigging: No sign of rust or cracks on fittings especially near holes. Clean rust, replace if cracked. Wire not kinked or frayed. Halyard works. Pins and shackles in good shape, especially those on the fore stay! Blocks turn freely. Ratchet block works. The forestay is the most stressed rigging on the boat. If in doubt, replace it with hardware from most any rigging shop. Length affects mast rake.

Steering: NO SLOP. If slop is present in through-hull bearings, replace bushings. They can be made or bought. If slop is from wear or corrosion on on vertical chock tube or steering head tube, replace. If slop is from push rod, either replace rod ends (new rods)by purchase form a supplier like McMaster-Carr or a parts supplier, or replace rod or pins (old style slotted bar stock). If slop in steering head, try tightening, or use tapered pin or bolt rather than spring pin, a machine shop can fix. Or replace the piece.

Hull: No cracked joints-fix with epoxy, fill cracks. Plank clip or plates tight. Mast base screws tight. Connection of blocks to deck tight. If any screws are loose, use sroong filler in epoxy to fill hole and re-drill. Tighten joints inside cockpit so rain and snow won't get into inner floor.

Plank: If warped, replace. Chocks ALIGN. Bolts tight and none stripped. If stripped, tap to next size or replace. See details elsewhere on alignment. Alignment is one of the most important items for speed!

Appearance: Your choice. Minimum requirement is to seal all wood with epoxy or varnish or paint, and especially cockpit floor to exclude moisture.

Structure: Mast step structure and listings between the floors are of most concern. If the floor is soft or you are worried about the mast step, the bottom skin can be removed by routing off the edges and glued areas. Inspect or repair and reskin with a good qality 1/8 inch mahogony, poplar or other light ply.

Mast: Sail track is clean, halyard works, bearing at base is strongly attached, hound is secure and not cracked at stay connection.

Boom: no splinters, blocks work. Generally straight.

Sails runners are obviously necessary, and are the speed locker. The more work and higher quality these components are, the faster you sail. Old and mangy still are fun for fun sailing.

Ken

Thinking about building

Hull Kits

[The bad news is that no one is packaging a kit as far as I know in 2004]

588

Posted by: Jeff Soderholm on December 02, 2001 at 08:54:36:

In Reply to: Thanks for your reply posted by Mike D. on December 02, 2001 at 07:11:09:

Mike I think the plans most use now are the wedge style or Gougoun plans which varying greatly from the original Sarns plans. I am not sure if those are wedge style plans that you have but I would make sure that they are if you are going to go through all the effort. I like the idea of the full size Goodwin plans as you can lay everything out right on the plans. I am sure Ken can provide better input on plans. Regarding kits Steve at Northwind Iceboats in Massachusetts has made kits in the past. He preforms the side panels and you glue the pieces up etc.. If you are interested in finding out more you can e-mail him at nth1@aol.com there is a list of prices of other equipment at the NEIYA unclassifieds site at http://www.concentric.net/~dn4762/events/postings.shtml
good luck and Think Ice!
Jeff

585

Posted by: Ken Smith on December 02, 2001 at 00:34:04:

In Reply to: DN Kits posted by Mike D. on December 01, 2001 at 18:23:28:

Mike:

No one is selling wood kits that I know of. Several of the shops selling hulls will sell partially finished boats so you pay labor instead of bucks.

Paul Goodwin sells plans and instructions as discussed elsewhere in the bulletin board. Try clicking on major headings, and brouse the messages. Raw materials are a short, though expensive list.

The major components are usually quarter sawn sitka spruce for the side boards, two pieces 13 feet long, 5/8 thick, seven inches wide. Narrower widths mean you may need to edge glue some to make the deeper portions of the sideboards, which is not a big deal. If you get 15 or 16 feet, the rest of the parts of the boat can come from that and the scrap. You also need 1/8 inch plywood. Light weight okume or mahogany or poplar is adequate. Birch is overkill. If any is making doors at a factory near you, door skins have been used in many boats. You will need three or four sheets for all the decks. You are covering the top and bottom so the 12 foot by 30 inch hull, but much is narrow. You will need a few small thicker pieces of wood, but lumberyard or scrap can work. You will need a gallon of good epoxy.

Your plank will need enough wood to make eight feet by seven inches by 1-1/4 inches in three layers.

All the hardware can be bought from Sarns.

Add boom, sail, rigging, and runners and you are off!

Let the DNboard know where in the world you are. Others will likely help.

Good Luck!

Ken Smith
DN4137

587

Posted by: Mike D. on December 02, 2001 at 07:11:09:

In Reply to: Re: DN Kits posted by Ken Smith on December 02, 2001 at 00:34:04:

Ken, thanks for your help.

I have a dated set of prints (dated Oct, 1991). This design doesn't have the concave bottom like what P. Goodwin has on his website. So I guess at this point I have 3 questions:

1. Is the concave bottom design worth doing vs. my dated prints?
2. You mention a 13 foot length for the sides. The list on this set of prints says 12 feet. Will 12 feet do it, or is 13 what I really want?
3. Lastly, the materials list calls for one 4x8 ply sheet for the decks and sole. This must mean there is a joint on the underside of the 12 foot fuselage. I haven't seen it called out on my prints, though. What station line is that joint at?

Again, thank you for your help.

Mike.

ps. I am located on the geographic southern fringe of iceboating, in Lincoln, Nebraska. Some seasons we have 3 full months of ice, like last year. Other years, we're lucky to get 6 weeks straight with safe ice.

590

Posted by: Ken Smith on December 03, 2001 at 00:49:47:

In Reply to: Thanks for your reply posted by Mike D. on December 02, 2001 at 07:11:09:

Mike:

To answer your questions:

1. Is the concave bottom design worth doing vs. my dated prints?

It is a preference thing. The boats look cool and provide a touch more ground clearance. They appear to me to be a tad harder to build, but I have not built one of them. Your plans will make an adequate - excellent boat. You will have a few lofting tricks to learn. I have two boats built to plans of the same vintage and Jan Gougeon is using the boat (modified, lengthened and repaired) that was used to make the 1988 vintage Gougeon plans. It will work fine. Most boats bring the stern up as far as the plans allow to keep from dragging the tail around, but this is not hard and if not done, is not critical.

You did not say whose plans you have. Norton and Gougeon would sell plans then. Both boats are sturdy and adequate. The plans in the yearbook make a good boat as well. Make the square pieces in the corners triangles, and these are Gougeon plans, almost.

Two mods are highly recommended: Make the boat a tad less than maximum length (12 feet) with maximum overhang at the bow. The Gougeon plans go toward minimum length for weight, but this is one of Jan's mods to his original boat to make it longer. Second, make the cockpit nearly maximum length. Read the board elsewhere to see why.

2. You mention a 13 foot length for the sides. The list on this set of prints says 12 feet. Will 12 feet do it, or is 13 what I really want?

12 feet will make a boat of near minimum total length. With the bend in the side, the hull length will be less than the plank length. This is okay, but the longer hull gives you a little more leverage to pull in the sail as the blocks are further aft. You need three bulkheads in the boat plus some a piece under the mast. This can come from your sideboard planks if there are no large scraps around your area. If you are goint to find a sitka plank to make the side boards, get two long enough for these pieces too.

3. Lastly, the materials list calls for one 4x8 ply sheet for the decks and sole. This must mean there is a joint on the underside of the 12 foot fuselage. I haven't seen it called out on my prints, though. What station line is that joint at?

Your choice. A five to one scarf joint is more than strong enough to deal with loads carried by the lower skin. The most highly stressed skin portion is between the bow and the dolphin striker under the mast. The joint will be behind than in any case. But most 1/8 (3 mm) plywood comes in smaller sheets than 4 x 8. Do NOT use cheap mahogany ply with white middle layer. It is strong enough, probably, but is splintery, poorly glued and hard to work.

A few other notes. There are two or three methods to build. This is what I used. Others build the sideboards and all the listings then add all the skins. Both work, its a preference thing.

A. The sideboard plank width should match the side board profile you want, deepest depth. You can edge glue some pieces from the trimmed off bow or stern to get the depth if it exceeds the material you found.

B. I do not remember where I read about building a DN before my first project, but it may have been in Think Ice. I had visited Tom Hammel, Joe Norton, and two other projects in progress, so I had a good picture of what others were doing.

C. I scarfed together the bottom skin, laid it out on a ladder-bench I built. The bench was built from two 2 x 6 x 12's with 1 x 3 cross members. If you make the table curved like the Goodwin profile, you get that bottom contour.

D. I laid out the boat on the bottom skin and glued the listings, longitudinal pieces, back-up blocks, and under-mast structure right to the bottom skin on top of the pencil lines from the plans.

E. I used a false bulkhead instead of the seat back to get the shape right and I fabricated teh bow and stern blocks. These get glued later. The side boards can be sawn and reglued on a fixture to get the curve, but I just glued them to the bow block one night, and bent them around my bottom structure and bulkheads and glued them to the stern block right on the table. I lifted them off to plane a nice square bottom surface and took off material to curve up the stern 1/2 inch or so, from the plank position aft. Then I glued the side boards and end blocks to the bottom skins and all the other structure.

F. The rear deck listings and structure went in next, as the exact shape could not be predicted by me until the process was at this point. The shape of the seat was the biggest pain, as it is slanted and joins a curves side.

G. Skin the floor, install knees, hand rails and foot brace boards, skin the forward deck, drill the holes for the steering tubes, and mount the hardware.

I built my first boat with a good saber saw, a hand plane, a borrowed table saw, and a borrowed router. Sawing the sideboards for the bend was the scariest cut. I needed help with that and I needed an extra set of hands for the side board bending and gluing. Make all the skins hang over the edge and finish with a laminate blade or a radius blade in the router.

No sweat.

Opti DN for kids

[See www.icesailing.org and go to the youth link to find plans, pictures and details]

626

Posted by: Doug Gaudet on February 15, 2002 at 10:44:04:

I got these three files from Jan Adsten of Sweden and I thought it might be good food for thought as to how we get our younger sailors into iceboating, cheaply, easily and with resources at hand.
Jan also sent me, along with the insert crown diagram, design diagrams for this DN-Optimist. It is smaller than a DN, very limited technical construction and uses an Opti's sail and mast. Jan advertises them in Sweden to get 10 - 16 year old in an iceboat which is inexpensive easy to make, and much more stable in various wind conditions. Also a good configuration for the "newbie's" from the softwater world.
I have emailed him for the last several days and he points out that it is not a DN but also it is not intended to be one. It is intended to get the young interested and older sailors out for their first iceboat adventure . Because, as some one pointed out earlier in the discussions last year, regarding beginners "a sailor who is iceboating for the first time will still find a "slow" ride on an iceboat FAST. My yacht club maintains about 10 Opti's for the junior sailing program, now whether they would let us use the rigging remains to be seen.
I have three files from Jan and would email them to anyone interested. They are not big and they are WORD documents, so they are easily viewed, saved or printed.

Think about this first

Love this boat

183

Posted by: Paul Goodwin on October 04, 2001 at 15:42:28:

I would have to disagree with the perception that the
current DN is too complex. There is a misconception
that you need to spend a great deal of time (or money)
to campaign a competitive DN. It is true that to win
the World Championship (or NA for that matter) it
helps to have an arsenal of highly tuned runners, the
latest carbon/glass mast, exotic chocks, sail tuned
to fit your particular mast, etc.

But if you look closely at the top sailors, you'll
find that a sailor can be very competitive with a much
more pedestrian setup. A glass (or carbon for those
with a carbon fetish) mast is pretty much a necessity.
Insert runners are also mandatory for top competition.
A plank tuned to each sailors weight is also a given.
The sail must be designed to fit the type of mast
you're using. After that, I believe it's mostly
smoke and mirrors (and perhaps a little sailing
ability -- don't you think???).

The reason the top sailors carry a pick-up truck full
of runners is to have the "ideal" runner for any ice
condition they may run across. If a sailor is willing
to give up the idea of winning on the unusual days
(3/4" of crusty snow, or 2" deep not-quite-frozen
slush), then you can get by with 2 sets of runners
for 90% of conditions. The two sets I use almost all
the time are 36" x 3/16" inserts, and snow runners.

Now, I do have more runners, and use them if the
conditions warrant. 1/4" inserts for heavy wind and
clear ice, angles for slush, and Sarn's plates for
sailing on dirty ice (they are easier to sharpen then
440C inserts). But I could easily get by without them.

While I've never won a World's or NA's, I think I'm at
least "competitive" (please don't burst my bubble
here...) Let's look at some of the "high tech"
components I use:

Mast: I used the same glass mast (from the initial
prototype build with Ron Sherry) for 5(+?) years
(it's now on Debbie's boat and going strong).
I replaced it with another glass mast, and have
had no problems with it. I don't plan on replacing
it this year (sorry Ron). And anyone who knows me
will confirm that I don't "baby" my equipmant!

Sail: I bought a Boston "F01" to use with my first
glass mast, and replaced it last year with a new
one because the old one looked so bad. I don't
know if the new one is any faster, but it sure
looks better. Neither of these sails were "tuned"
to fit my particular mast, they were stock "off
the shelf" sails.

Runners: Last year I used 3/16" inserts whenever
the snow was less than 1-1/2" deep, and sometimes
deeper if it was windy. The rest of the time I
used standard Sarns bullnose runners or snow plates.
There were a couple high-wind days when I used the
1/4" inserts, but it was rare. I put the angles on
a couple of times too, but they're usually more of
a novelty than a necessity.

Hull: I've been using the same hull for seven years.
It's been torn apart a couple times, but I just
glue it back together.

Plank: Four years old. I may replace it this year
with a stiffer one. Some people think it's because
I've been gaining weight, but I won't admit it
until I have to join the "100 kilo club".

Chocks: I use a very sexy set of "Strubleized"
chocks. This is the only thing on my boat I would
consider "high-tech". After going to a bonded
chock setup (no alignment possible), I wanted the
stiffest, straightest chocks possible. These fill
that bill perfectly.

Boom: I broke my 8 year old wooden boom (I sheeted
it in half during a regatta, too much adrenalin
I guess). So, I replaced it with an aluminum boom
last year (Forstmann).

Other than that, all my stuff is standard Sarn's
hardware.

The bottom line is, to win races (or at least come
close), what you REALLY need, is a good set of
basic components, runners which have been highly
tuned, very good sailing (specifically iceboating)
skills, and perfect alignment. The basic components
are easy to come by. The runners are also within
reach. It's the "highly tuned" part of the
runners, and the sailing skills that are difficult.

There is definately a skill to sharpening runners.
You'll probably never get it by trial and error
(error is the key word here). You need to learn
how to sharpen runners from somebody that's already
going fast. I'm willing to show people what I know
about it, but you have to ask me. The sailing
skill, well, what can I say. Practice, practice,
practice. There are sailing skills that you can
get by asking (and listening of course). If you
are having trouble with something specific, ask
me and I'll tell you what I know, even if it's
not much.

Oh, and by "perfect alignment", I don't mean just
runner alignment. The alignment of the plank to
the boat, and alignment of hardware on the hull
are also critical to getting the boat tuned up on
both tacks at the same time.

Hope to see you on the ice, we're in this together!

649

Posted by: John Davenport US4961 on March 12, 2002 at 15:55:38:

In Reply to: Thanks, Paul, good decision. posted by Bruce Lowstuter on March 12, 2002 at 11:26:26:

Hi Bruce,
The beauty of this board is that you can ease back and watch the activity and if you feel you want to interject your opinion, you can jump right in. Most of my friends think I have an opinion… I don’t find it surprising at all that mast defection numbers are not published or readily available. It is something that is coveted by many. In Ron’s cast, he could make a mast made of pasta go fast. Many won’t talk about their runners much either. Interestingly, the faster a person gets, the more likely they are to tell you what they were using and why. The Gougeons are wonderful to talk to because I always walk away a little smarter because they make you think. I have been using Jeff’s masts for 3 years now and I have gotten much faster. Maybe as fast as I will ever get because I sail with my head up my ### most of the time. I’m sure I would have had the same jump with Ron’s masts too, but I got to know Jeff when I worked at Harken... I think the point for me is that I can make everything but 2 parts. The mast and the sail. I might get faster if I bought a plank too, but I like making planks. And as far a trickle down is concerned, I haven’t seen an aluminum or wood mast at a big regatta for a while. Except at out regionals where we encourage EVERYONE to show-up and join in. The reason I might want another mast would be that I wanted a different deflection. Just like anything else, they have evolved. The new masts are faster and lighter for sure. If you want a softer mast, it is difficult to soften them by sanding, without compromising the wall thickness. They are pretty thin now days. Although I saw a friend talk a belt sander to his mast at a regatta this year right in front of the launch site. I would never do that to a good mast. I would rather sell it and get another. Frankly, they are not that much money. People say DNs are expensive, but have you ever counted the SUVs in the parking lots at a regatta? $35,000 over 5 years! As far as Paul is concerned, he won’t buy a new mast until his falls apart. And why should he, he is fast with what he likes. You should see his favorite sail. I think it is an old paint tarp. I should know, I see it from behind enough. My point is just pry the wallet open and buy a mast. Unless you really over bend it, it will last for a long time, be more fun to sail and you will go faster. My group has come to the conclusion that time spent on runners is more meaningful. There is where you can really make strides. Here is another argument for the expense of DNs. How many of us own a soft water sailboat AND are members of a yacht club? How about the annual Rum budget? Now for the important stuff, the “Western Region Spring Regatta” is this weekend March 16th & 17th (414) 299-9305 Hotline update Wednesday night at 9:00 p.m. We can swap masts there. John Davenport US4961 Western Region Rear Commodore

648

Posted by: Paul Goodwin on March 12, 2002 at 15:51:56:

In Reply to: Thanks, Paul, good decision. posted by Bruce Lowstuter on March 12, 2002 at 11:26:26:

How does Ron beat me around the course??? Hmmmm.... it
must be the mast. Yeah, that's it, if I can get one of
"those" masts (one of the masts Ron uses of course, not
the ones he sells to other people), then I could beat him
at the next Worlds. OH YEAH baby, now there's a plan!

Actually, I get to sail anything of Ron's I want. Most of
our (local) boats are pretty much interchangable, and we
can take an entire rig and move it from one boat to another
without even adjusting the stays! You can learn a lot by
doing this, and sometimes the knowledge is humbling.

The problem with swapping parts (or whole boats) with Ron
is you find out pretty quickly that he isn't winning by
keeping any secrets up his sleeve (or up his mast for that
matter). What you buy from Ron when you order something
is exactly what he puts on his boat at a regatta, he doesn't
use some "secret" mast that was hand selected. What gets
Ron trophies at DN regattas is the same thing that gets him:
1) 1st place trophies at Renegade Regattas,
2) 1st place trophy at a Northwest Regatta "Free-for-all"
(sailing a borrowed Skeeter).
3) Behind the wheel of the overall winner in the Detroit
to Mackinaw race.
4) etc, etc, etc...

What Ron has is loads of experience and training in making
sailboats go fast, and then pointing them in the right
direction when it counts. Ron is meticulous in setting
up his boat. He checks his runners for nicks after EVERY
race, and takes the time to fix them. He goes out and
checks for wind shifts on the course. He practices starts
and mark roundings. He looks at other boats to see what
makes other sailors go fast. Always watching, always
tuning, always checking and rechecking, and always open
to new ideas.

I'm still learning, and will probably never have the
skill level (or the drive to win) that Ron does. But
I pride myself in doing well with minimal equipment, and
I try to keep the stress level low. I'm proof that you
don't need all the latest trick gadgets to be in the top
ten at the Worlds. You need a basic set of good hardware,
and learn to get the most from what you have.

Ron has been slowly and steadily improving his masts.
The biggest change is weight reduction by using carbon
fiber in place of glass fiber. I think he has taken
something like 4 lb out of the mast by using some carbon.
The carbon mast also has a faster (better?) response
time - it snaps back faster after a gust. The downside
is the carbon mast is more costly, and more fragile than
the glass mast. The other big change is he has developed
several (lower) stiffness levels in the carbon mast.
This has been an advantage for light weight sailors (which
doesn't help me at all).

You make an interesting point about Ron and Jeffs "disservice"
to the class by not divulging the stiffness of their masts.
While it might spur some additional sales, I think the
reality is the only truly interested sailors are the ones
trying to develop their own composites masts. Giving them
all the info to do so would hardly make good business sense.
I'll pass the idea by Ron and see if he bites - but don't hold
your breath waiting for the results...

Helmets

218

Posted by: hugh stephens on January 06, 2002 at 10:04:26:

Are there specific requirements for helmets. I understand that hockey helmets are not permitted. Are there other requirements and where can they be found. I am planning to buy a boeri short cut ski helmet. Thanks.

219

Posted by: WWBL on January 06, 2002 at 11:16:08:

In Reply to: helmets posted by hugh stephens on January 06, 2002 at 10:04:26:

I use my motorcycle helmets but the full face-shield models restrict lateral visiblility, are prone to fogging, and they are heavy. The good news is that they are max protection and are very warm. Snowmobile helmets are lighter and don't fog. Both of these types tend to be fairly bulky and are likely to get caught on the boom, which could be dangerous in a tight spot.

I saw the Boeri ski helmets and they are fine but do not have the optional chin guard the Jofa helmet offers. I called on the helmet sale ad in the latest Runner Tracks (1-800-307-7439) and they only have blue large Jofas left but the price is right at $50. Jofas are only 20 oz. but adequate protection. They have several levels of quality.

You will be fine with the Boeri (ski shops say they are better than Jofas but almost all iceboaters wear Jofas), a face mask like for snowmobiling, and a pair of good ski goggles.

Will 5133

243

Posted by: Roger Duffy on March 03, 2002 at 12:02:24:

In Reply to: Re: helmets posted by WWBL on January 06, 2002 at 11:16:08:

I use my hockey helmet which has an Itech full face shield attached. This is a clear plastic shield with vent holes to prevent fogging. If the weather is very cold, I cover the vent holes with saran wrap. If I start to fog up, I poke my finger through the saran wrap, thereby recreating the vents, trying to keep them to the minimum needed for fog prevention and yet still provide wind protection.

Down forces

391

Posted by: Jay McIntyre on January 07, 2004 at 18:43:38:

can anyone tell me how to figure how much downforce a sail produces on the mast base, I'm running a 18' mast with about 55 sq ft sail.
any help will be appreciated
Thanks
Jay

393

Posted by: Ken Smith on January 07, 2004 at 22:39:05:

In Reply to: down force created by sail. posted by Jay McIntyre on January 07, 2004 at 18:43:38:

** CAUTION ** Incomprehensible engineering gibberish and the need to do math follows! **

Jay:

You have not provided enough information to answer. It is a fairly complex problem, but this may provide enough information to allow you to estimate.

Firstly - Consider the whole boat. The boat will not be tipping over, so the total sail force acting sideways at the center of effort times that height (upsetting moment) will equal the weight-boat plus skipper- acting at the center of gravity times the distance to a line from the from the front to a one side runner (righting moment). The sail center of effort is about one third back from the mast leading edge and between a third and .45 up from the boom, depending on roach of the sail. These two products can be considered equal (upsetting moment and righting moment).

Secondly - Consider the mast. The windward shroud and the forestay act at the hound attachment point at some angle (both horizontal and vertical) to hold the mast up. The upsetting moment of the sail must also be equal to the moment of the shrouds acting on the mast about the base. This is a vector solution and involves some trigonometry, which will not be explained here. But the total force of the shrouds acting parallel to the ground times the distance from the base to the hound is the "mast moment" and it is equal to the other two moments above. Using some math, solve for the tension in each wire (fore stay and shroud). Note that sheet tension can be ignored for now, because its direction of action does not act to balance the sail force sideways. By now you have Tfs (tension in the forestay due to the sail) and Tss (tension in the side stay due to the sail).

Thirdly consider the main sheet. All the force in the main sheet is balanced by tension in the forestay. A new balance of moments, this time main sheet tension times the number of parts at the end of the boom times the distance from the mast base to where the main acts on the boom is the "sheet moment". It is balanced by the product of a new hunk of tension in the forestay acting forward on the mast times the distance from the base to the hound. Since you know how hard you can pull on the sheet, solve for this new bit of forestay tension called Tfm (Tension in forestay due to mainsheet)

Now start adding forces. The part of the total forestay tension (Tfs + Tfm) acting parallel to the mast (times cosine of the angle between the forestay and the mast), plus the part of side stay tension acting parallel to the mast (Tss times cosine of the angle between the side stay and the mast), Plus the main sheet tension times all the number of vertical legs of the main sheet, The sum of these three forces is your mast step compression. Call it MSC.

If you are still with me, now you need to get a safety factor in to deal with errors, with mast bend, with dynamic loading, etc. If you sail with lots of mast bend or with loose shrouds, the sail also develops down force. It can be estimated, or handled in the safety factor (make it bigger). I'd try 1.3 for a safety factor to start. If you like extreme bend or very loose shrouds, 1.5 might be better.

Design the structure under the mast step to take at least the safety factor times MCC.

MCC goes up with mast rake, sheet tension, mechanical advantage of the sheet, total weight, boat length and boat beam. The bigger and heavier you make it, the bigger and stronger it must be, by a lot.

A sixteen foot Hobie mast developed enough force to extrude delrin at the base. A DN forestay tension deforms 304 stainless 1/4 inch steel pins. These forces can be high.

Good luck.

Ken Smith

Racing

“Buoys”

663

Posted by: Tom Austin on March 23, 2002 at 17:07:06:

Looking for a design for some club Marks. I have made some before but they were to small and did not last. The ones I have seen lately were about six feet tall and fit into an old sail bag for easy transport. What materials are recommended? Wood or PVC? What is the rule about the traffic cones that are also set out? Are these considered part of the Mark so that you are disqualified if they are hit?

Print out form , fill it out, and mail it.
5) You will them have the plans, specifications and all the
current paid-up members IN THE WORLD! You will then know
who you are sailing with as it has all the sail numbers.
BEST WISHES TO ALL FOR "button bay" ICE FOR THE WORLDS!

664

Posted by: Ken Smith on March 23, 2002 at 21:49:25:

In Reply to: Ice boat marks posted by Tom Austin on March 23, 2002 at 17:07:06:

I have two marks made from some hardware store or scrap aluminum thin walled tube extrusions. You can get much fancier, but these are simple and adequate. The top of three poles are drilled and a loop of 3/32 wire cable is through them. Each leg is fastened to each other leg near the bottom with a length of cable. Each side is an equilateral triangle. Wood would work as well, with a nail extended-tip to grab the ice. PVC is bendy and slips on the ice. Orange nylon (fabric store), or orange mesh (hardware store) s used on at least two sides for visibility.

A piece of line from the top goes down to a screw eye (cheap but a starter hole required with a wood or spade drill bit) or an ice anchor. The line is pulled tight and tied and that holds the mark in place and keeps the legs spread. Mine are about 4 feet long and are plenty visible for club marks. 6 foot legs and these are regatta quality.

Cones, a.k.a. sister marks, are marks if the racing instructions say so, or become part of the mark if they are tied to the mark, and something like orange or yellow safety tape works well.
The Europeans put darling marks about 10 boat lengths to weather of the leeward mark and to leeward of the weather mark. It is forbidden in the racing instructions to pass between the darling marks and the nearby mark. This keeps port tackers from getting a nose in around the weather mark, and keeps starboard tack boats a little distance from the leeward mark so there is maneuvering room at the finish and at each mark rounding.

665

Posted by: Paul Goodwin on March 26, 2002 at 10:52:55:

In Reply to: Re: Ice boat marks posted by Ken Smith on March 23, 2002 at 21:49:25:

I guess I can spew some of the "by the rules" crap that nobody
like to hear, and many people just choose to ignore anyway.

The IDNIYRA generally follows the NIA rules, and the NIA
specifies that an iceboat course may have no more than two
marks, aligned with the wind. So far there has been little
desire from most (NIA) governing board members to change
this rule.

This means that "darling" marks are not officially allowed on
an IDNIYRA course. The Europeans have chosen to ignore this
NIA rule, as they have ignored a lot of the other rules over
the years.

In North America, we have not used darling marks in an
official regatta, even though many sailors think they help
with safety on the course. However we have used orange
cones to provide a little working distance between the
boats and the marks. We have conformed to the NIA rules
by tethering the cone to the mark with a line, and we can
say the cone is part of the mark. Without the tether, it
would be quite a stretch to claim the two seperate pieces
are actually just one mark. Since the cone is part of
the mark, a boat hitting the cone has hit the mark and
should be disqualified.

As far as mark designs go, Bill Buchbinder in Traverse City
(Michigan) has built several sets of marks for people,
and has refined his design over the years. The set he
built for the Gougeon Brothers is the best set of marks
I have seen yet. They are very portable and easy to set
up, and are visible on a 1 mile course without any
difficulty. These marks use a fiberglass tubing for
the legs, which seems to be a good compromise between
stiffness and strength. You'll have to contact Bill for
more info.

Starting

Posted by: MIKE OBRIEN DN US 3456 on April 10, 2000 at 08:38:46:

In Reply to: Re: Adequate inventory. posted by MIKE OBRIEN DN US 3456 on April 10, 2000 at 07:54:43:

Well might as well just open another can of worms!

When in the Worlds at Montreal 1999 I noticed on a number
of starts, when mixed in with some of the good fast boats,
that some people don't keep their appropriate runner near
their starting block. In some cases they actually were 3 feet
in front of the starting block. I asked a few sailors if this
was taking place at the Worlds this year in Sweden and it
still was.

I have always thought you were required to keep your runner
heal at the block until the flag drops. However since seeing
this trend I thought it would be good to check and see if this
point was covered. It is not in the year book.

IS THIS POINT COVERED IN THE NATIONAL ICEBOAT AUTHORITY RULES?
Could someone who has a copy of that rule book respond with a
on this point. It would be nice to have a clarification.

This is not sour grapes. If it is allowed I intend to move
as far forward as the boat above or below me does!
It would however seem to make more sense if we were
required to keep the boat stationary on the block till
the flag drops.

MIKE OBRIEN DN US 3456

This might seam like a sour grapes issue

Posted by: John Davenport on April 10, 2000 at 11:01:54:

In Reply to: Re: STARTING posted by MIKE OBRIEN DN US 3456 on April 10, 2000 at 08:38:46:

I have seen this many times too. It is awkward to say to the guy below on the line who has encroached 3 feet up the line towards you to move back down, but isnâ€™t it really he who has caused the awkward situation? Rules are rules, I agree completely. I think it is easier to enforce if there is a member of the race committee who walks the line before the start. I agree with your thinking about enforcing the 9-runner issue too. The trick is getting it done in a timely basis before the start of the regatta. At the 1999 GC in Finland, the race committee had a second line (staging line) behind the starting line. The idea was to get the next fleet ready earlier. We could use that second line as a hardware check-in before the first start of your race in the regatta. You have 3 runners on your boat and 6 others with you. You get stickered or stamped, take your 6 back to your pit spot and move up to your starting block, done! This could be done without any vote too, because it is simply enforcing the rule not changing it. There is nothing written as to when the 9-runner rule is to be imposed at a regatta. The race committee can dictate when, I would think.
John Davenport

Posted by: Jane Pegel on April 10, 2000 at 16:40:35:

In Reply to: Re: STARTING posted by MIKE OBRIEN DN US 3456 on April 10, 2000 at 08:38:46:

In the Racing Rules of the National Iceboat Authority,
Part II, Management of Races
E. Starting
3. Starting Procedure
b. Each yacht's windward runner is placed at the starting block,
odd numbers on port tack, even numbers on starboard tack
if the port and starboard tack start system is used.
c. The race Committee shall check to make sure all yachts are
laid off (headed) similarly and the Committee has the
authority to require a yacht to alter her heading.
d. There shall be a prepaatoyr signal approximately 1 minutes
before tthe start. This shall be a visual signal made by the
started standing near the leeward mark. He shall raise a flag
or raise his arms. This may be accompanied by an audible
signal (megaphone or ggun)
e. The starting signal shall be the lowering of the starter's flag or
arms. It may be accompanied by an audible signal. The
visual signal governs the start, the audible signal is only a
supplement.
f. After the starting signal, skippers may begin to move their
yachts away from the starting line, either by pushing or
sailing.
1. No yacht may be in forward motion at the starting signal.
2. A yacht that arrives at the starting line after the starting
signal must come to a stop on the starting line before
beginning the race.

Please note that the runner is positioned at the starting block.
Please note: the official NIA starting line does not have a wire.
When a wire is used, the sailing instructions should clearly state how a yacht is positioned on the line.

Shop Stuff

800

Posted by: Luke Buxton on March 18, 2003 at 06:37:49:

I would like to embark on making a sanding machine this summer and was wondering if someone had plans or some ideas on what works and what does not? I have some sort of an idea in my head but i would like to hear opinions and suggestions? thanks

804

Posted by: Bob Gray on April 04, 2003 at 15:42:29:

In Reply to: Sanding Machine posted by Luke Buxton on March 18, 2003 at 06:37:49:

I assume you are talking about a belt sander for runner sharpening. Gilliom Mfg Inc. makes kits for various power tools including a belt sander. I built one several years ago and expanded their plans to incorporate a 90 inch belt. At that time the kit and plans cost about $90. Their phone number is 636-724-1812. You have to supply your own motor.

Hull

Hull Plans and Options

329

Posted by: ASHLEY DN 4442 on November 24, 1998 at 17:29:01:

In Reply to: Looking for Building Plans for DN and Used Boats posted by Phil LaCourse on November 22, 1998 at 12:46:10:

1) Easiest plans available at best price!
2) Go back to main IDNIYRA web page
3) Go down to the second item, membership
4)

306

Posted by: Paul Goodwin on September 30, 1998 at 07:25:35:

In Reply to: dn fuselage construction posted by Marty Fredericksen on September 27, 1998 at 22:52:50:

I think there are a few things which can help make a DN tunable,
whether it is fast or not depends on how good you are at tuning.

1) Adjustable mast step position - it adds very little weight, so why
not.

2) Adjustable plank position - same as above.

3) Maximum length cockpit - allows the sailor to get his weight
forward when sailing downwind.

4) Seat back at maximum rearward position.

5) Make sure the side stays are exactly the same length.

6) EXTREMELY IMPORTANT for optimum tuning - make sure the front
runner, mast step, plank, and sheet blocks are in one plane on the
fuselage. This is different than just putting them in the center of
the hull, since hulls are not always perfectly straight. I set the
hull on a table, level it from side to side, and run a string down the
length of the hull (elevated about one foot). Then I use a plumb bob
to carefully line the string up with the front chock and the sheet
blocks. Next use the bob to mark the positions of the mast step and
plank. This takes a little practice and skill, but is very important.

Good luck on your project!!!

808

Posted by: Ken Smith on May 20, 2003 at 22:21:06:

In Reply to: wood source, materials list posted by Chester Javis on May 20, 2003 at 05:09:35:

Chester:

You are near the cradle of the DN. Contact Paul Goodwin for local materials suppliers, or of course, Ron Sherry. Use the phone, meet the people. Join the class and get a yearbook with the numbers.

What you will need:
2 ea 5/8 x (6-1/8 to 8-1/4(pick preference = D)) x 12'6" sideboards
Best: quarter sawn Sitka spruce.
2 sheets 1/8 inch (3 mm) plywood skins Best: Okume

1 ea 5/8 x D x ~6' bulkheads, under-deck structure, listings, seat back
Best: Sitka

Misc. soft wood and side board scrap for mast support structure, nose blocks, tail blocks

2 ea 1/8 X 4 x 16" plywood side reinforcement by plank attachments
Best: Birch plywood

1 ea 1 x 3 x 6' finger rails (optional)

2 ea 5/16 x 7-1/2 x 8'2" Plank skins (or build up from strips)
Best: Ash

2 ea (1/4 to 1/2) x 7-1/2 x 8'2" Plank core ( or one twice as thick)
Best: hardware spruce or poplar near minimum

1 gal Gougeon epoxy and slow hardener.

2 chocks

2 sets of plank attaching hardware

1 steering chock and oilite bearing

1 steering rod

1 tiller post and bearing (5/16 longer than D, max side board height)

1 Tiller rod square tube

1 mast ball

1 adjustable mast base

2 deck blocks and attaching hardware

1 ratchet block and hardware

dolphin striker, wire, attaching hardware

Chain plate (bow)

2 Shroud attachments (plank)

Shrouds and hardware for mast and adjusters

Mast, sail

Boom with three blocks

Sheet

Tiller (plywood and wood handle or as desired)

And runners.

Good luck! See you on the ice. Buy a set of plans and templates from Paul Goodwin, and get detailed instructions.

Ken SMith
DN 4137

Hull shape and modifications

Concave Hull Bottom

537

Posted by: Doug Gaudet on January 25, 2001 at 07:57:23:

I was lucky enough to finally get off this rock (PEI)and travel to the Nova Scotia for the 2001 Maritime Championships. Eight years of sailing DNs and I had never been in a formal race. But there was no wind for two days, so there was lots of time to stand around and look at other's equipment, drink "warm" liquids, eat fine foods and converse with great people.
Several of the boats have concave bottoms. I asked and was told it gets the mast step higher into the air thus raising the sail plan. I have a couple of DNs built to the 197(4) Gougeon plans. Are these new boats I saw utilizing the hull spec (I think it's A-14) that states the bottom can extend a max of 1 inch above the baseline zero. Is this the spec that they are utilizing to get the bottom curve, and is it just to get the sail plan higher?

538

Posted by: Paul Goodwin on January 25, 2001 at 08:21:24:

In Reply to: Concave hull bottoms posted by Doug Gaudet on January 25, 2001 at 07:57:23:

I can only speak for my own design, but the curve in the bottom
was done with no thought to raising the sail plan. The reason for
the curve under the mast step was to raise the bobstay strut a
little higher off the ice. There was a time when hitting the strut
on rough ice was fairly common. The minimum length of the strut
was reduced to help this problem, but there was still the occasional
bottoming. So by raising the bottom of the boat another 1/2" or so,
it gains a little more clearance. I actually bent the strut on my
boat two seasons ago on a chunk of ice, but that was the only time
in 7 years of sailing my current hull.

You also have to keep in mind that the DN hull is flexible (some
much more so than others). My design tries to minimize stiffness
(we could debate the merits of this all day...), and the hull
will deflect more than an inch while sailing. This reduces the
clearance for the bobstay strut.

Raising the sail plan an inch (relative to a 16 foot mast height)
would have very little effect on performance. If this was
significant, then we wouldn't see the Gougeon's lowering their
sail as they've been doing lately.

539

Posted by: Warren Nethercote on January 25, 2001 at 19:40:50:

In Reply to: Re: Concave hull bottoms posted by Paul Goodwin on January 25, 2001 at 08:21:24:

Paul,

I'm one of the fellows that Doug was referring to. When I built my hull in 1992 or 1993 I was still of the 'more mast rake is better' school, and so the curved baseline let me build with minimum depth side planks, to control weight, and yet still maximize relative height between the mast step and the stern blocks - allowing more rake. Of course, as masts got bendier, and more upright, the rationale disappeared. Probably a waste of effort, given that I built the hull from the bottom skin up, thus complicating the construction jig. There's a second negative side: as a relatively light fellow I have soft planks (of the order of 100 to 110 lbs/in) and the droopy stern than bangs on the ice, rather than the bobstay strut. But a boat with a curved bottom profile does look nice!

If I were to do it again I'd probably only raise the profile forward of the plank, as you show on the drawing on his own website, to let me keep some paint on the stern!

Warren Nethercote
DN 3786

540

Posted by: Paul Goodwin on January 26, 2001 at 08:04:14:

In Reply to: Re: Concave hull bottoms posted by Warren Nethercote on January 25, 2001 at 19:40:50:

Warren,

My hull profile isn't just elevated under the mast step, but goes
one step further. The profile also goes below the zero line at the
plank, giving the bottom an "S" profile. Since the boat sits on the
plank, having the bottom go below the zero line effectively raises
the stern. In reality hitting the stern of the boat occurs more
often than hitting the bobstay strut, although it is much less of
a problem with the stiffer planks that have become popular.

As far as your "waste of effort" building the hull from the bottom
skin up, that is my preferred method of construction. Ron Sherry
also starts with the bottom skin and works up. I don't recommend
it in my building instructions because I think it is harder for the
first time builder, but it saves time and provides a truer bottom
for the seasoned builder.

Hull Materials

Side boards

320

Posted by: Ken Smith on November 02, 1998 at 21:54:48:

In Reply to: Sitka spruce info please posted by Ed Atkeson on November 02, 1998 at 17:48:16:

In response, here is my engineering judgment. Others know more, but I have built boats and observe others. I have been in most every active shop and seen how the others make the hulls go together.

Sitka spruce has the best strength to weight ratio and is adequately strong for the stresses it sees on a DN at the minimum allowed dimensions. Other woods can work also. Redwood is lighter and not as strong, but can work if maximum thicknesses are used on the side boards. Cedar boats (Port Orchard or other high quality material) is light enough but not as strong. Several cedar boats are out there and seem to be holding up okay. Basswood, other spruces, poplar, pine, and mahogany boat sideboards have been built and used as well. They are sometimes heavier.

Poplar or light mahogany plywood is adequate for the decks and skins. The area at the corners behind the seat back and in front of the front bulkhead sees the most stress and should be doubled or reinforced if lower strength plywood is to be used.
Cedar or redwood is more than adequate for little stiffeners, internal structure and the like and can result in a weight savings.

My current boat has side boards consisting of a layer of Sitka and a layer of cedar. This makes for a stiff boat which resists splitting at the highly stressed areas. I have also seen splices and edge glued boards to build up smaller boards to the desired dimensions. I am at or near minimum weight (added hardware not weighed).

I recommend lower than maximum heights on side boards to save weight, a fuselage wide enough to allow sheeting the boom to the blocks and not displace your shoulders, and reinforcing materials at the stress areas near the plank. Lots of minor variation on shape and height and width, so take your pick.

Near minimum weight hull is good for my 200 lb body.

Good glue joints are essential. Make the boat legal: Get the dimensions right and make the boat square and in plane.

The three most important things to build into the DN for speed are: alignment--straight and parallel chocks; alignment--straight runner edges with the right crown, and alignment--everything true and parallel when the boat is hunkered down and sailing. After that, its easy.

There is NO magic in a hull. ‘Tis the nut on the tiller what makes 'er go.

596

Posted by: Jeff Kester on December 08, 2001 at 04:32:49:

Attached is wood property info I've found on the net. Has anyone used yellow poplar in the hull or plank core. I've heard of basswood or Doug fir as substitutes for Sitka, but the data seems to show poplar is closer in properties. It's also cheep and readily available.

For the plank skins I'm considering yellow birch. Is there a reason that ash is used more prevalent?? I'm on the heavy side at 220lb.

Tree Species	Average Specific Gravity	Oven Dry Sample Static Bending Modulus of Elasticity (E),	Impact Bending Causing Failure Compress Parallel to Grain	Height of Drop Max Crushing Strength Compress. Perpen. to Grain	Fiber Stress at Prop. Limit Shear Parallel to Grain	Max Shear Strength
Hickory, Shagbark	0.72	2.16	67	9,210	1,760	2,430
Birch, Yellow	0.62	2.01	55	8,170	970	1,880
Ash, White	0.6	1.74	43	7,410	1,160	1,910
Redwood, Old-growth	0.4	1.34	19	6,150	700	940
Redwood, Young-growth	0.35	1.1	15	5,220	520	1,110
Douglas-fir, Interior West	0.5	1.83	32	7,430	760	1,290
Douglas-fir, Coast	0.48	1.95	31	7,230	800	1,130
Douglas-fir, Interior North	0.48	1.79	26	6,900	770	1,400
Douglas-fir, Interior South	0.46	1.49	20	6,230	740	1,510
Yellow-poplar	0.42	1.58	24	5,540	500	1,190
Spruce, Sitka	0.4	1.57	25	5,610	580	1,150
Pine, Ponderosa	0.4	1.29	19	5,320	580	1,130
Basswood	0.37	1.46	16	4,730	370	990

600

Posted by: Bob Rast DN1313 on December 15, 2001 at 10:38:05:

In Reply to: Wood selection in Hull & Plank Construction posted by Jeff Kester on December 08, 2001 at 04:32:49:

Regarding wood species for hull sides, I would highly recommend finding and only using AIR DRIED lumber. Spruce seems to be the most reliable and I have not seen any failures using Air Dried Spruce, Aircraft grade is available from several sources. You Might try Aircraft and Spruce Supply, They are on the Internet, WWW.aircraft-spruce.com or 1800-831-2949 and have spruce in various sizes they have 5/8 x 6" about $8.00 a foot , you can glue up several pieces to get the height needed. As far as other species, I’ve seen Kiln dried spruce fail right below the mast step after 1 ride, and I’ve seen cedar sides split from end to end. If you are only trying to build a day cruiser and don’t expect to race you might try basswood or something else but should probably fiberglass the inside and outside with some fine deck cloth to keep it from splitting. Building a hull is a lot of work and you dont want to spend all that time and have it break after a few rides. If you are near Wisconsin, McCormack lumber in Madison has a large inventory of air dried spruce . Or check with other local sailors for sources for Spruce. as far as the plank Air dried is still preferred. but some people use kiln dried ash without problems. with your weight you will probably need a maximum dimension plank with ash skins on the top and bottom. Check old articles on plank construction.

666

Posted by: Konrad on March 30, 2002 at 19:58:50:

I'm poised to begin construction of a "recreational" DN. (no one races around here and our winters are sometimes iffy for iceboating) Hull weight is important to me, but by no means can I afford to obtain Sitka spruce for the side boards and structural components. (One of the alleged hardwood stores in my area said they'd never heard of "Sitka" spruce) So you can see what I'm dealing with here.

So... I'm looking at the alternatives. I have an old post by Ken Smith that lists a few other species, and one of them is poplar. I can obtain pretty good looking poplar. That's alternative # 1.

I can obtain a species of spruce called "D-Spruce" in 1x4 dimensions. I don't know anything about D-Spruce. This stuff is very light colored with a tight grain and seems to weigh very little. Ken's post that I've referred to also states he's seen some boats with edge-glued sideboards to build up to the needed height. I guess that's alternative # 2.

For those of you who have the experience, which alternative would you choose?

Any help is greatly appreciated.

667

Posted by: Doug Kolner on April 01, 2002 at 09:40:48:

In Reply to: Alternatives to sitka spruce posted by Konrad on March 30, 2002 at 19:58:50:

Use Douglas Fir.
We have beautiful Doug Fir flooring at the local yards.
It's heavier than Sitka but not that much. It's stronger too.
I built a DN that weighed in at 53lbs using this wood.
Pick through the pile for lighter pieces. Sometimes the lighter
colored boards are lighter in weight.
You will need 3 boards per side. I cut off the tongue and groove
before I edge glued it but I'm not sure that's necessary.
Cost is ~25% that of Sitka.
Use light woods like western red cedar for internal non-important
parts and use the trimmed off Fir scraps for mast step, cockpit
bulkhead and plank mount areas.
For the skins I used 1/8" Baltic birch that cabinet shops use for
drawer bottoms (not the stuff used for doors which is soft)It has no voids and the inner lam is strong as well.
It comes in oddball sizes (50"x50" sheets) but is really cheap.
I paid about $15.00/sheet. 2 are needed. You'll have to do 2 splices
on the bottom but none on top if you run your cockpit knee thwart to thwart.
The money you save on wood should be used above the deck (ie mast & sail) and for good insert blades.
Best of luck on a fun project!

688

Posted by: Doug Gaudet on June 06, 2002 at 09:52:37:

In Reply to: Alternatives to sitka spruce posted by Konrad on March 30, 2002 at 19:58:50:

Konrad, I've just read your note of March, and have to stick my cheap nose in for my 1 cent.
I live in PEI Can, and like you, Sitka spruce is something we read about in books. I asked and asked 10 people and got 11 opinions. Using the old Gougeon plans,(1976), I finally found relatively clear PINE, don't ask me what kind. I was more concerned about knots at this point than fiber strength. I used Industrial Formulators epoxy - cold cure, and the 1/8 inch ply was $5 a sheet, today that cheap ply is still only $11 CDN. Everything was coated 3 times with epoxy.
I put that boat thru it's paces in the 10 years since, it won't be gold , but I've been clocked at 55mph with the new sail.
There are pictures at: www.virtuo.com/icesailing , then go to gallery and then new pics from 98-99. Email me if this is of any help.

670

Posted by: PaulGoodwin on April 03, 2002 at 09:32:44:

In Reply to: Alternatives to sitka spruce posted by Konrad on March 30, 2002 at 19:58:50:

For my boat, I would use the poplar over Douglas Fir. Another good choice is cedar, but I would increase the thickness to 3/4" since cedar is a little weaker (and lighter) than Sitka Spruce. I've seen some nice light weight boats built of cedar that lasted for many years. Even in a recreational DN light weight can become important at the need of the day when you have to carry the boat up and put it on top of the car.

But, a Douglas Fir boat should be very strong. If that's what you can find locally, go for it and don't look back...

Plywood

796

Posted by: George on March 15, 2003 at 19:04:21:

The plans call for marine or aircraft plywood. My 'local' yard (Johnson's Workbench in Charlotte, MI) has "Marine Okume" in 1/8" and also "Marine Lauan Ribbon" plywood in 1/8. They don't have mahagony in 1/8. I have no idea if these are strong enough, look halfway decent or if I should seek out the mahogany (any yards in mid-michigan???). Can anyone shed some light on this? Three of us are starting boats and we will all use the same materials, so the cost of a wrong decision here is large! Thanks in advance.

797

Posted by: Ken Smith on March 15, 2003 at 22:36:59:

In Reply to: What kind of marine plywood? posted by George on March 15, 2003 at 19:04:21:

Okume is the plywood of "choice." If none was available, then we could discuss alternatives. We cannot find a source for the stuff in Ill, so a group mounted a fund and one of the guys drove to Harbor Supply on the Eastern Shore of Maryland to pick up thirty sheets. We are using "bending ply" because it is $10 cheaper per sheet, and seems fine, and finishes very pretty.

Luan is a generic tropical wood, and inconsistent. Most of it is splintery and the core wood is very soft. It IS light.

I've seen boats in Finnish birch, mahogany, walnut, and others. I have used poplar ply ("light ply") for interior trim and bottom skins, but is too soft for decks and seats. I got that from Bulsa USA, Menominee,MI, a RC airplane kit company.

Birch, especially aircraft quality, is strong enough but a little heavy and it doesn't finish as nicely as Okume.

Go for it!

798

Posted by: Charlie on March 16, 2003 at 06:54:53:

In Reply to: What kind of marine plywood? posted by George on March 15, 2003 at 19:04:21:

Okume is Mahagony.

Hull Repair

370

Posted by: TOM LANDERS on February 04, 1999 at 12:42:21:

In Reply to: Re: Sitka spruce posted by Steve Andreae on February 03, 1999 at 14:16:34:

I had this problem with my boat. If the crack isn't too far from the bottom or the top, i drilled from the closest surface for approx. 1/4" to 3/8 dia. dowels to go thru the crack. Depending on the length place the dowels approx. 2" to 3" apart. I glued "epoxy" the dowels and the crack. If you want more strength try a metal strap on the inside to be secured with screws and glue. I found my metal straps at the hardware store. In one case i did as above and also skinned it with fiberglass cloth and resin on the outside. If you take your time it turns out pretty nice.
Good luck.
Tom Landers
810-629-5953

371

Posted by: Ken Smith on February 04, 1999 at 23:49:42:

In Reply to: Re: Sitka spruce posted by Steve Andreae on February 03, 1999 at 14:13:15:

This is one of the most stressed areas of the boat, the side boards above the plank. The boat cracks here because the twisting of the hull applied by the mast is transferred to the plank near this point.
The problem is worse if the plank is held on with plates outside the hull, as in the older plans, rather than through plates under the floor. Flexing of the plank can add bending to the side board through the plates.

The problem is also worse if one side of the plates is not set so the plank studs can move in 1/8 inch (3 mm) toward the boat as the lank flexes. Ten minutes with a round file can fix this.

Most plans call for plywood reinforcement or glass reinforcement in this area, either outside or inside. The strength is required in the up and down direction, so the visible grain or glass fiber orientation should be oriented this way.

Dowels are stress risers, and may hold the side board together, but may cause problems later. I would not use them. Epoxy filled with medium or high strength filler is stronger than the wood. Pry or drill to open the crack slightly and fill with epoxy. Clamp closed and let set. Add reinforcing wood or glass to the outside. 1/8 (3 mm) inch mahogany, or 1/16 (1.5 mm) inch birch aircraft ply is probably ok to prevent recurrence. Alternatively, 12 oz unidirectional glass oriented vertically, or 16 oz woven glass can do the same. The reinforced area should be 4 or so inches forward and aft of the edges of the plank in the extreme plank positions and come up at least 3 inches or more from the bottom edge. The birch ply is available in most hobby stores and many craft stores in the US, and is relatively easy to find.

This year you will see some long knees in boats at the nationals extending from the seat to well forward of the plank, formed of plywood in a radius filling the corner inside the cockpit. These are stronger than the above. They are a SOB to build and fit, however.

Welcome to the home built fun of the sport!

Ken Smith, Jr.
DN 4137

Cockpit Floor Thickness

727

Posted by: David Bishop on November 24, 2002 at 22:41:33:

I have the 1991 DN plans, but can't tell what the cockpit floor thickness is supposed to be. At the top of sheet 2, the plans note that the floor beams are 1/4 x 5/8. At the bottom of the same page, sections C & D show a 1/4 x 3/4 ledger and 1/4 x 3/4 centerline bridging (between the floor beams). All of these things are between the cockpit floor and the bottom deck, so they should be the same height. Am I missing something, or do the 3/4-inch heights and 5/8-inch heights not jibe?

728

Posted by: Ken Smith on November 24, 2002 at 23:03:14:

In Reply to: Cockpit Floor Thickness? posted by David Bishop on November 24, 2002 at 22:41:33:

The listings between the floor and the bottom can be most any convenient thickness. Most I've seen are 3/4 inch, because the listings (strips) are cut from a 3/4 inch thick board. Redwood, bass wood, cedar or remaining bits of sideboard materials work fine. If the sideboards were planed to 5/8, that becomes the desired dimension. The boards on the drawing you are using probably started at 3/4 or more, were planed to 5/8--hence the confusion. The Polish boat I sailed last year used 10 mm listings. With 3 mm skins, the total bottom thickness was 16 mm, or about 5/8 inch total.

IMHO, the thickness is better thinner, so the pilot can hunker lower and be out of the wind and the side boards need not be so high. The purpose is to keep you from falling through the boat. Some torsional rigidity comes from thickness, but gussets (in lieu of knees) do much more to provide torsional stiffness.

Ken Smith
DN 4137 US

Cockpit Footrests

729

Posted by: John Jombock on December 03, 2002 at 22:56:59:

Consider this nightmare: Bob and Jimmy and their DN pals are sailing their favorite lake on a beautiful breezy February afternoon. Bob is sailing his sparkling-new varnished hull, which features sawtooth footrests. The gang decides to cruise to the highway bridge at the far end of the lake. They beat to windward, carefully crossing a melted-down pressure crack on the way.

After some beam reach hot-dogging for the benefit of people driving across the bridge, they head back to the launch area, Bob in the lead. Flying downwind, Bob decides he can safely sail across the old pressure crack in the area they crossed earlier. Bob is wrong. His steering runner drops through a thin spot. The boat stops instantly. Inertia propels Bob to the front of the cockpit in a microsecond. Sawteeth tear into his upper legs and lower torso.

Jimmy and the rest of the gang see the disaster ahead, stop and rush to Bob’s aid. They find him gravely injured, bleeding profusely. A cell phone call to 911 starts an EMS rush to the lake.

With considerable difficulty, the DN gang gets Bob back to the launch area. They apply pressure to Bob’s wounds in an attempt to stop the bleeding. The EMS ambulance arrives, and Bob is rushed to the hospital, 25 miles away. Seven hours of surgery and a week in intensive care save Bob’s life, but now he faces months of rehab.

Is the preceding scenario a real possibility? I think the answer is YES! I think the IDNIYRA should outlaw sawteeth in DN hulls. To protect others, we don’t allow sharp points on the front of runners. Let’s protect ourselves by outlawing sawteeth. What do you think?

John Jombock, DN1513

730

Posted by: mike obrien on December 04, 2002 at 08:12:29:

In Reply to: Killer Sawtooth Footrests posted by John Jombock on December 03, 2002 at 22:56:59:

The first stepped footrests I saw were on Joe Nortons
Boat in 1979 or 1980. They were a good solution to replace
a combersome adjustible bar used before then. Granted the
DN has more speed/interia potential since those days. The
design of the stepped foot rest has come a long way as well.
My last (2) boats utilized a balsa construction with a fiber-
glass outer edge layer. Since Balsa is not strong in shear it
makes an excellent break away material. In fact you have to
cap the balsa with the Mahagany plywood, extended off the top
of the side rail, to actually keep in intact!

The (2) possible scenerios in the impact are as follows:

1). Your feet are on one of the rungs at impact. The rung
shears and the fiberglass edgelayer compromises all
other steps at the same moment.

2). Your feet are at the front of the cockpit. As if you
were underpowered or going downwind. Either the cockpit
front bulkhead gives way or your legs hinge upward at
the knees. Either you hips are going to brake the knees
as you slide forward and brake them in the week balsa
exposed dimension. Or the action of your lower leg section
being forced upward will accomplish the same.

I aggree some of the knees out there are to rigid and might
be damaging in a bad scenerio. I'm sure there are many ways
to design knees that break away.

What is the worst nightmare on the DN in the frontal impact.
I would have to think it's the tiller! In most cases their
rigid and pointed directly at your organs or head.

My tiller has a curved section. That design was stolen from
I think John Glueck to help steer the boat with your knees.
Well its real good feature has saved me twice. It hits you in
the crotch, mine has a good slope so its friendly, and lifts
the handle over your head.

All the accidents I have seen injury usaully results from a rigid
or straight design of the tiller. Some work was been done on a
break away set up but it has not been readily adapted.

I am improving my break away plank attachment. Hopefully I have
a race worthy craft,after breakaway incident, if needed.

I'm also working on breakaway stay attachments but time will
propably run out for this season on that feature.

Second to the tiller, however, the design of the seat back
puzzles me. Every time someone brings up this issue it gets
shot down. Why do still have the very dangerous seat back
above the deck line? Necks and back are vunerable enough when
racing but what about during an accident? Its a projection
and its extemely rigid and non forgiving.

Mike OBrien DN US 3456

731

Posted by: David Wilkins on December 05, 2002 at 20:12:33:

In Reply to: Killer Sawtooth Footrests posted by John Jombock on December 03, 2002 at 22:56:59:

John,
I completely agree with you on this one. I've raised this issue before. Saw toothed hiking racks are a bad idea.
I hit a open patch at top end speed last season and slammed my can into my front bulkhead on my way out. No sharp edges on my boat. A busted rib, bruised boat and body was all I recieved.

D. Wilkins

732

Posted by: Jim Olsen, DN 2221 on December 11, 2002 at 18:44:26:

In Reply to: Re: Killer Sawtooth Footrests posted by David Wilkins on December 05, 2002 at 20:12:33:

I think Mike is right on. I made a nice laminated curved tiller which survived a lot until I finally broke it in an icehole encounter. (I'm using one of those bad straight ones right now, but will make a good one again soon.)

[Did he mean a hole in the ice, or a collision with another discourteous driver?]

Cockpit seats need a redesign badly. They are awful on one's back, and probably contribute more to not sailing than any other design flaw. There are days that I don't want to sail anymore because my back screams at me to stop. (Curved backs would help)

I have saw tooth footrests and I love 'em. (You'll only get mine from my cold dead hands!) There's no reason 'though that they couldn't be redesigned. Is there some sort self-camming design that would work with wood saw teeth and a balsa wood break away stop? I don't like things that break off and have to be re-glued; particularly when it is totally visible on the deck.

999

KMS NOTE in 2004

Ladder foot rests have become more popular. The bottom and top are of 1/8 inch plywood, the steps and sides are ¾ by ¼ strips. The sides and separate and support the steps. The top pieces (2) are shaped to leave room or the foot and are glued to the intersections of the sides and steps. The bottom is full size. The sides fit to the hull sides, the front hits the forward bulkhead, and the back touches the knees (little triangles that support the boat’s sides).

The part is laid in place or taped.(or glued). You catch your heels in it.

Hull Finish

693

Posted by: Jeff Brown on August 05, 2002 at 12:09:29:

I am about to finish my new hull and I want the natural finish of wood to show with a clear glossy coat.
Should I use West System for the outer coat, using the specified additive for finish?
Or,
should I do the first coat with West System to seal it, then use a Marine Spar Varish for several coats?
My experience with varish has good results, but I am not certain about its use for cold weather resistance.

Also, I am not familiar with using the West Syetem finshing coats, but I know of the special thinning resin to add to 505 for gloss finish.

What do you all do for those glossy supreme boats I see? I want my boat to look its best!

694

Posted by: Bob Rast on August 05, 2002 at 19:09:28:

In Reply to: Hull Finishes - Natural Glossy posted by Jeff Brown on August 05, 2002 at 12:09:29:

Here is how I do it .First seal the hull with west epoxy,Use a 3inch foam roller and foam brush to smooth out finish. I use the slow hardener which seems to be clearer than the fast which has a red tint.I wet sand with 220 grit wet paper on a rubber block until all orange peal.,(bumps) are gone.then sand with 320 or 400 if you wish. Ive used Captains spar varnish which is extremely hard and durable but has a slight yellow tint to it.Apply with foam roller and smooth with foam brush. It can be wet sanded to take out imperfections between coats ,2 or three coats is plenty.after the last coat you can wet sand with 600 grit and even buff with a machine and compound if you want it real smooth.Apply wax go sail and try not to drop the mast through the deck or bump into any one.If you want a real clear finish look into Interlux clear 2 part finish.

695

Posted by: Tim Polaski on August 06, 2002 at 15:10:08:

In Reply to: Hull Finishes - Natural Glossy posted by Jeff Brown on August 05, 2002 at 12:09:29:

A tip I received a while ago....after you seal with west, wipe the surface with alcohol (Fantastic Cleaner is OK, it has alcohol) before sanding. This minimizes clogging of fine sandpaper and can save you some ching in sandpaper. I have one coat of west and 3 coats of spar varnish...looks great!

696

Posted by: Luke Buxton on August 06, 2002 at 15:45:37:

In Reply to: Hull Finishes - Natural Glossy posted by Jeff Brown on August 05, 2002 at 12:09:29:

I like to put two thin coats of west using the 207 special harder then wash it down with joy/water mixture then wet sand it out with 400 grit. As for varnish I like Petit bak-v spar varnish hold up well and is easy to use. Use a good badger hair brush 17-25 dollars good luck can't wait to see it

697

Posted by: Paul Goodwin on August 06, 2002 at 22:55:48:

In Reply to: Hull Finishes - Natural Glossy posted by Jeff Brown on August 05, 2002 at 12:09:29:

A lot of good comments here already, none that I wiould
say are wrong, just different approaches.

I can comment on some things I've picked up on over the years.

The stuff that clogs up sandpaper when sanding West epoxy is
an "amine blush" that forms on the surface during cure. The
amine blush is water soluble, and at the Gougeon shop (I doubt
if anyone has sanded more West epoxy than the workers at the
Gougeon shop) they attack the problem by scrubbing the surface
with water and a "hairy pad" pior to sanding. A "hairy pad"
is a Scotchbrite abrasive scrubbing pad - get a pretty coarse
grit. A little soap or ammonia added to the water may help a
bit too, but make sure you rinse off any residue - varnish
and soap don't mix well. Solvents can work too, but cost more
money than water and can have significant other side effects
as well.

West 207 hardener is formulated just for coating, with special
attention to color (it's much more clear ititially and long term)
and viscosity (it flows out better). Additionally 207 has
additives to help with ulraviolet degradation. If you decide
to use 207, don't forget that it uses a different mix ratio,
and requires different pumps - don't get them mixed up. The
other West System hardeners need a cover coat of a good spar
varnish with ultraviolet inhibitors to protect the epoxy from
sunlight.

At the cost of raising the wrath of all the old time finishers
out there (and maybe Luke too), sell the badger hair brushes and
switch to foam -- works better and cheaper too. I don't think
there's any need to use a roller on a DN because it's so small,
but the roller/brush method can't be beat on big surfaces for
speed and quality of finish.

By the way, anyone interested in buying any of my old badger
hair brushes????

699

Posted by: Paul Goodwin on August 07, 2002 at 15:19:07:

In Reply to: Re: Hull Finishes - Natural Glossy posted by Jeff Brown on August 07, 2002 at 11:35:56:

You pretty much have to roll on the epoxy (207 or other hardeners)
in order to spread it out evenly, so don't worry about bubbles
from mixing, you'll generate plenty of them with the roller.

The key to getting rid of the bubbles is to "tip off" the epoxy
with a foam brush. This "tipping off" is simply going over
the epoxy coat with the tip of a foam brush. This breaks the
bubbles, and smoothes out any ridges left behind from the roller.

With a little practice, you can spread a coat really quickly, and
maintain a smooth high-quality finish. When covering large areas,
it works best to have one person rolling, and a second person
tipping off. On a DN, one person can handle the whole job easily.
Coat a small area (one rollers worth), tip off, then roll the next
section, tip off, etc. The surface texture may look a little rough
right after tipping off, but it will flow out fairly quickly.

The first coat will mostly soak in. You can proceed directly to
varnish from there, but I usually apply a second coat of epoxy.
The epoxy builds up faster than varnish, and is a tougher coating.
The second coat of epoxy should flow out to a glossy finish.
The downside is that you will have a good amine blush after that
second coat that needs to be washed off before sanding. The other way to handle the blush is to save a step and just wet sand. Having learned finishing from the auto body side of painting, wet sanding comes naturally to me.

207 has no solvents (as far as I know), so there aren't really
any more noxious (or obnoxious) vapors than with other West
hardener/resin mixtures.

Working time - I have no idea, but it's never been a problem,
probably 20 minutes or so.

Coat the whole boat at once, at least for the first coat. If you
do a second coat, the big problem is figuring out how to support
a boat covered in wet epoxy while you finish the final section.
I usually do the bottom first and let it cure. Then I can sand
any drips that have wandered from the bottom onto the sides
before coating the rest of the boat. Then I coat the top
surfaces, followed by the side panels. 207 is pretty low
viscosity, so you need to be a little careful and not apply
too much on the sides or it will run/sag. But there is no
reason to build up a heavy layer anyway, you want just enough
the obtain a gloss and allow for sanding (otherwise you're
just adding unecessary weight).

Schedule??? Here's my recipe:
1 coat of epoxy to seal the wood.
1 coat of epoxy, should be glossy at this point.
1 or 2 coats of spar varnish, 2-part urethanes have the best toughness and durability (and cost the most of course).

DN's spend the majority of their time out of the sun, so a thick
multi-layer coating is not usually necessary for durability.

By the way, don't judge my finishing ability by the looks of
my current boat. I used to live by the "if I can't win at
least I can have the nicest looking boat on the starting line"
philosophy. Now I'm trying to follow the Jan Gougeon philosophy,
which obviously must be "looks like hell, goes real fast".

701

Posted by: P. Ashley on August 10, 2002 at 12:48:07:

In Reply to: Re: Hull Finishes - Natural Glossy posted by Luke Buxton on August 07, 2002 at 20:53:25:

BUBBLES - When first coating new wood I made the mistake of putting a cold plank in a warm room. Yes! Thousands of bubbles - Hat pins don't handle the problem.
"Soak" your plank in a warm location. Then move it to a cooler location - wait 15 minutes - then start coating with epoxy. The thousands of bubble locations become craters as the air in the plank contracts. Then recoat using the same technique. Use slow hardener.
I asked Meade G. once about a vacuum chamber. He said that putting ones mixed epoxy (slow hardener) in one for a minute or two after mixing prior to coating would get most of the bubbles out. Use a trap to protect the pump. Ease on the vacuum to prevent the mix from frothing over its container (fill container only half full).
I would like to know how those beautiful boats stay so pretty. Don't we all wear spikes????

702

Posted by: Rich Potcova on August 13, 2002 at 10:25:41:

In Reply to: Re: Hull Finishes - Natural Glossy posted by P. Ashley on August 10, 2002 at 12:48:07:

Since we're on the subject of hull finish, has anyone used a 2oz or 4oz fabric over areas that require a high gloss finish ? I understand these lightweight fabrics are primarly used on strip canoes and other simular type projects. Seems that using a fabric along with epoxy would greatly improve durability. Does this add too much weight ? Has anyone tried this ?

703

Posted by: Jane on August 14, 2002 at 11:41:33:

In Reply to: Re: Hull Finishes - Natural Glossy posted by Rich Potcova on August 13, 2002 at 10:25:41:

We built several cold molded red cedar 16 ft. class M scows and applied 4 oz cloth to the outside using WEST system and followed with Z Spar Captains varnish. I don't know how the weight was affected because the boats were under the class minimum and had to carry lead.
However the glass made the surface more resistant to dings that the boats that did not have the glass. But this was on a sailboat. I'm not sure that with a DN dings are a major problem, except with the runner planks. The glass does not improve the durability of the varnish. With the 4 oz cloth it is virtually impossible to see the weave of the cloth, but this is over red cedar. Might be diffent over sitka. I wouldn't bother on the hull. In fact, I only put one coat of WEST on the hull and then go with varnish Because I think that additional coats of WEST adds weight. For sure additional coats of WEST act as a primer under the varnish and make it look very glossy, but the WEST is a pain to sand and is heavy.

704

Posted by: Paul Goodwin on August 15, 2002 at 06:25:00:

In Reply to: Re: Hull Finishes - Natural Glossy posted by Rich Potcova on August 13, 2002 at 10:25:41:

Many years ago I built a Tornado catamaran, and used
some techniques that were developed by a developed by
a full-time Tornado builder. He recommended using 4oz
cloth over the wood, and found that it actually weighed
less than using epoxy alone (using the proper techniques).
Here is the reason why:

1) Glass is less than dense than epoxy, so for a given
coating thickness the overall weight is lower.

2) The glass acts as a "screed", and controls the coating
film thickness. The final coat (minus any finish coating)
is only as thick as the glass and is uniform over the
whole boat. When applying just epoxy (in the multiple
coats that would be required) the film thickness varies
and is much thicker than required in some places.

Additionally, the glass adds abrasion resistance and helps
to insure the coating is impervious to water intrusion.

However the DN is an entirely different beast than a
Tornado cat. It isn't sailed in the water, is subject
to much less abuse, and film thickness variations would
have less effect on the overall weight since there is
much less surface area.

On my DN's, the only place I use glass is in the cockpit,
where I apply 4oz cloth over the cockpit floor to provide
some abrasion resistance. This really does help reduce
the damage done to the floor of the boat when entering
the cockpit. i also use some glass on the side panels
around the plank area to help keep the sides from splitting.

I agree with Jane, one coat of epoxy is all that is
required. On my last boat I didn't apply any epoxy,
just varnish, but it was actually more work in the
end because the varnish took several coats to gloss out.

Steering

Caster (Tilted pivot)

332

Posted by: Dan Gidcumb on November 28, 1998 at 09:37:51:

Has any one experimented with adding caster to the front runner chock? Specifications allow for it but I have never seen anyone use it. From a steering geometry perspective, it really makes sense and is used on automobiles to snowmobiles. With properly matched caster and runner crown, the runner contact with the ice would form an arc when turned. This would facilitate a faster turn with less skid friction than in the more common vertical alignment, enhancing speed out of every tack and jibe.

888

Posted by: Paul Goodwin on August 31, 2004 at 12:44:50:

In Reply to: Steering kingpin posted by John on June 21, 2004 at 08:52:28:

I prefer raked, but some other sailors do not. It's another
area of design where there is no "best method".

One thing to keep in mind, if you use a Sarn's "low profile"
front chock (the current standard) then keep the rake angle to
4 degrees or less. Otherwise the runner stiffener may interfere
with the chock.

884

Posted by: BobRast DN1313 on June 25, 2004 at 19:23:17:

In Reply to: Steering kingpin posted by John on June 21, 2004 at 08:52:28:

Assuming the bottom of your boat is flat or at least the bow I would draw a line across bottom locating the bottom hole. The using a square, square up the sides of the fuselage and draw a line across the top. Locate top hole approximately 1/4 back from this line. Raked is definitely better than straight up and down as you turn the runner the edge tilts away from the turn adding a better angle of the edge to the ice.

Front pivot loose

240

Posted by: Geoff Sobering on February 11, 2002 at 17:08:26:

Over the weekend I discovered the front steering tube had worked it's way loose. During the process of re-epoxying the tube to the nose of the boat, I'm sure I've wiped any surface coating of lubricant of off the oilite bearing surfaces. Is there anything I should specifically do (or avoid doing) when I re-assemble the steering chock?

242

Posted by: Bob Rast on February 13, 2002 at 22:05:08:

In Reply to: My Oilite bearing busted loose too posted by Will on White Bear Lake on February 13, 2002 at 21:05:34:

I had one loosen up a while back. Probably form faulty prep. I was able to pull out, resand hole in boat with coarse grit paper. sand tube well , for added grip I put it to my bench grinder adding large grooves. If you don’t want a big mess on the deck, tape off hole with packaging tape. Apply glue to hole and tube. Sand epoxy into tube with some coarse paper, add filler to remaining glue cover tube and wood inside boat with epoxy filler mix, insert wipe epoxy and remove tape. I have added a spring to the top of the steering post so the post doesn’t bottom out and bang tube possibly loosening,

825

Posted by: John on November 07, 2003 at 12:43:16:

Greetings all,

My older DN has a West System Graphite steering post bearing. Over time it has worn to the point where there is slop in the tolerances. This is effecting both the steering feel and tractability of the craft. I have a new bronze bearing and want to install it for the upcoming hard water season.

Couple questions:

1) Best practices for drilling new hole
2) Installation
3) Angle degree canted aft (looking at my other DN it is canted aft)
4) Any been there done that's

Thanks all, this is my loaner boat and want to make it the best first experience for newbies.

JJS (DNUS5023)

P.S. I am in the NE Southern CT

826

Posted by: Ken Smith on November 07, 2003 at 20:54:15:

In Reply to: DN steering post bearing installation advise posted by John on November 07, 2003 at 12:43:16:

I am not familiar with the exact bearing you have, but I've removed, moved, and replaced bearings several times.

If the bearing will come out, take it out after tapping it sharply with a heavy hammer. A socket of the right size can help, to spread the load onto the bearing. If it is all composite and will not move, you can drill through it to get it gone.

Once it is out, there are three posibilities: (1) the hole is too big, (2) the hole is too small or (3) the hole is at the wrong angle.

Objective: set the new bearing so rod on the steering chock is centered side-to-side and set it so (when looking from the side) it is either straight or raked aft, meaning the top of the rod is behing the bottom of the rod. Either situation is okay. If you are using cables for steering rather than a rod, raking the chock means the cables will be slightly slack when the front chock is compressed. With a rod, the runner turns a little when the boat is bouncing. This does not occur as much if the chock is straight up and down. The theory is that the boat is more dirctionally stable (returns to straight if the steering is turned) with a little rake. If so, the stability is weak. Some think you can turn better with rake as the advancing blace leans as you turn, placing the lead ice contact edge more square to the ice. If so, the ideal angle is about 3-5 degrees. Remember the plank squats, so even a straight installation will act raked under sail.

New Sarns chocks are powder coated, and this coating may need to be worked a little for proper fit. If so, a light polishing compound will loosen stuff up by moving it in the new bearing. Clean the compound out thoroughly to stop wear from continuing.

The location of the bottom of the bearing is set by the front chain plate. The Sarns hardware is drilled so the inner oilite (bronze) bearing protrudes into the chainplate, fixing the end in steel rather than in wood. If this is your hardware, its best to have the chain plate on before the glue sets up in the bearing. Plan ahead.

Now, fix the holes. If undersized or not straight, drilling and a rasp will allow the holes to be adjusted until the new bearing will fit. If oversized, a little glass wrapped around the bearing can fill the gap. The epoxy will eventually be strong enough by itself, but the glass may help hold things still until the glue sets up.

I put some vaseline on the inside and stuff a piece of rag in it to keep out epoxy during gluing. Wash the outside of new aluminum tube (bearing housing) with soapy water and/or a oil-removing solvent. Acetone should be the last washing step.

I sand the aluminum with course sand paper just before gluing and inserting, so the surface cannot oxidize again. If you have an airplane project in the garage, a two part etching primer or chromate primer can be applied. Don't go looking for it if you don't have it. Its is just for perfectionists. Mix up some epoxy and "wet sand" the aluminum housing with unfilled epoxy wetting the sand paper. Add a strong filler to the rest of the batch, like coloidal silica or milled glass fiber for strength to a peanutbutter consistency. Butter the wood with a generous coating.

Insert the bearing. Add epoxy mix to fill any gaps on the bottom and then put on the chain plate. Press the bearing down all the way into the chain plate. Add epoxy mix to the top and form a little fillet, if the bearing protrudes through the top deck. Clean up teh excess before it sets.

Done. Lightly oil the chock when you put it in. Re-oil in the spring when the boat goes to sleep and in the fall in prep for the season. If you keep it lubed, it will not wear the new bearing.

Ken Smith
4137 US

Tiller

559

Posted by: Rob on March 21, 2001 at 15:31:30:

What is the best way to build an extendable tiller in side or out side? If outside how do you get the shell around to fit closely to the tiller (using Sarn’s shaft)

557

Posted by: Ken Smith on March 23, 2001 at 07:01:31:

In Reply to: tiller construction posted by Rob on March 21, 2001 at 15:31:30:

Tiller construction, for a "box" outside the tiller.

1. Make a fiberglass tube: Wrap two thicknesses of wax paper around the tiller. Wet about a foot of fiberglass tape in epoxy, wrap it around the tiller so you make a glass tube about 6 inches long. When set up, mark the top before you remove it from the tiller and trim it to 4 inches long. The tiller extrusion is not perfectly square, and knowing the top will make the fit better.

2. Make the handle. I trim some light plywood into shape with two sides and a back. Glue some 1/8 plywood to make gussets (stop for the tiller extrusion which also strengthens the box). Leave 1.5 to 2 inch extension on front to fasten body. Sand and ready for final finish

3. From 1/8 plywood, cut shapes for sides, top and bottom. Top and bottom, as an alternative, can be thin strips of left over batten material or listings, if you made a boat. Any shape to taste. I prefer a top piece wider in the middle than the ends for esthetics and strength. The sides often include a three inch down shape to make knee-steering easier. I don't close the front six inches of the bottom so I can have access for a stop screw.

4. Glue the glass tube and handle to the top piece. Remember the tiller will stick through the tube and you are going to put a glue fillet between the top and sides. Plan accordingly. The wide top provides this clearance.

5. Glue the side pieces to the top, tube and handle. Glue the edges and put a small fillet on the inside. A small spacer to act as a stop (tiller pushed all the way over the tube) is sometimes used and a small spacer holds things square. Too much clamp pressure at the glass tube will distort the tube and ruin the fit.

6. Edge glue the bottom on. You can get a short length of fillet at the front where the gap is left, and you get a good glue joint in the handle. If the angles or fit are weird at the handle, fill the gap with filled epoxy.

4. Glue a small nut to the top of the tiller. Speed tip: It’s the nut on the tiller that makes the boat go fast.

5. Finish. Install. Use a stop. A screw or bolt through the bottom aft end of the tiller extrusion will keep the tiller on. You work through the gap you left in the bottom piece. Alternatively, later Sarn’s tillers have a slot on the bottom. A screw through the glass tube into this slot will act as a stop.

An easy one day or two night project.

Ken Smith
DN4137

558

Posted by: Paul Goodwin on March 23, 2001 at 08:32:20:

In Reply to: Re: tiller construction posted by Ken Smith on March 23, 2001 at 07:01:31:

I would disagree with Ken on one point. He suggests wrapping the
tube with two layers of wax paper. This will leave a gap and make
the fit sloppy. There are few things that inspire less confidence
in driving an iceboat than sloppy steering.

What we do here in the Motor City, is wax the tube 2 or 3 times
with a good paste wax or mold release (Johnson's paste wax is
the old standby). Then wrap the glass directly on the tube, and
overwrap with a layer of polyethylene plastic (a long strip of
garbage bag works ok). Oh yeah, you need to make sure the tube
is perfectly smooth, so go over it with some 400 grit wet-or-dry
sandpaper on a flat block to polish it up before you start.

Put the whole thing into the oven set as low as it will go
(around 130 deg F). Let the epoxy cure for a couple hours, then
remove it and allow to cool completely. Note: it's best to do
this when the wife is shopping.

The next step is to break the sleeve free from the tube. It
will form a slight bond, so it can take a bit of force. It helps
to cool the whole thing down in the freezer first to shrink
the aluminum. I can usually break the sleeve free by grabbing
the sleeve and pounding the end of the tube on a wood block.
Occasionally I've had to use brute force (the hammer) to free
it up. It can also help to thump all sides of the sleeve with
a hammer (the no-rebound shot-filled kind work great for this),
the shock will help break the bond.

Putting the tube in the oven not only cures the epoxy, it
expands the aluminum just enough to allow the sleeve to
slide after it cools. The result of this is a sleeve with no
play, maybe even a slight interference. There will be a little
friction, which works out just perfect.

By the way, this is how Ron does it too...

Another difference between my construction and Ken's (not saying
his method is wrong), I use 1/4 spruce for the side pieces. Cut
the sides with the desired profile and glue them to the glass tube.
Next is a spruce block where the end of the tube stops (when the
tiller is collapsed), and a spruce block at the back end. Then
1/8" plywood on the top and bottom, no need for fillets, and no
fancy cutting. Just glue the skins on and trim after curing.

559

Posted by: KenSmith on March 24, 2001 at 01:18:09:

In Reply to: Re: tiller construction posted by Paul Goodwin on March 23, 2001 at 08:32:20:

Isn't creativity great? With the two layers of wax paper, I need neither hammer nor power. The gap is about .006 inches after considering the epoxy shrinkage. I detect no wiggle or sloppiness. The glass is more than strong enough without an oven or pissed off wife. The ones I've broken have all been in the wood, usually from falling on them. I am still reusing old tubes over and over. But hey, I am hanging on in the end of the Gold fleet, not the top.

Lets talk a minute about creative tillers. I will do an article for runner tracks with more details but:

-- Triangular cross section with distorted plywood sides. Stiff, pretty, light and functional. (mine!)

--adjustable boat hook for tiller body, plastic snow shovel handle. Ajustable and lockable for starts. Not light. [Owner unknown]

--A real crutch. [Bob Cummins]

--bent wood strips and a box around the tiller. In a collision, the bent wood pushes the aluminum down and breaks. [Jim Beck, as seen on several western regional boats]

--Two fiberglass tubes from the steering post to a formed fiberglass handle, the two tubes potted in epoxy to fasten to the post. Stiff and non-adjustable. [Bernt Zeiger, among others]

--A six inch wide piece of plywood (no stiffening) on aluminum hinges fastened to the tiller post. Maximum width to clean up air flow over the pilot. Clean, safe, but don't push the boat with it. [I should know, but I forgot]

--Carbon fiber tube with a Shepard’s crook bent to a vertical handle, finished bright black and beautiful. Light, stiff, expensive. [Is the carbon fiber a clue? Jeff Kent]

--Wood sides bent to strange dips to ease knee-steering. [Many]

Three days of no wind sure lets one see lots of creativity at the worlds.

Ken Smith
4137

Runners

History

???

Posted by: Paul Goodwin on April 08, 2002 at 09:42:51:

In Reply to: Instert runners vs. plate steel runners posted by Konrad on April 05, 2002 at 19:41:45:

Actually, inserts are the "new school" technology!!!

I know a little of the history, plus I recently acquired one
of the original boats (#46) built in the Detroit News workshop
in 1937, so I know what runners were originally included in
the design.

Here is my (extremely long) take on the history, though others
may dispute it. But that's the beauty of the bulletin board,
I'm sure someone will correct my mistakes. Plus others may be
able to fill in any holes I left in the timetable.

The original DN (called the "Blue Streak 60" when it was
designed) came with 36" angle iron runners. Angles were
typical on iceboats of the day (along with cast iron runners
for the big boats). These runners were simple affairs, with
the angle held to the bottom of an oak body with wood screws.
This simple design worked well enough for the original runners
to hold up during more than 60 years of iceboating (and they
still look fine today).

The second set of runners for the old DN was plate runners.
These were 30" long mild steel plates with wood filler pieces
to make up the 1" thickness required to fit the chocks.

Later in it's life a third set of runners was built. These
were 36" "T" runners. Like the angles, the T stock was
held to the bottom of an oak body with wood screws.

All of this took place before the advent of the "DN".
In 1953 the DN Association was formed, and the specifications
for the class boat were hammered out at the Cartwright home
on Cass Lake. Prior to this, the DN was built in different
styles based on the whims of the builder. At that time,
the new DN class settled on 30"-36" wood body runners
(angles, T's, and "file stocks"), and 26"-30" plate runners,
with the basic dimensions as listed in the specs today.

In 1972 the DN Association organized the first World
Championship, and later changed it's name to the
International DN Ice Yacht Racing Association. To accommodate
the Europeans, the specifications were relaxed to make it
easier to find appropriate runner steel in Europe. This was
the origin of the 20% allowance made for the thickness of
the steel to accommodate DIN sections. This change to the
rules opened the door for "max" and "min" T's.

With the Europeans coming over with T runners substantially
thinner (and thicker) than "standard" American T's, top
competitors felt the need to expand their runner quiver
with the extreme T sections. A rule requiring runner
steel to be "commercially available sections" didn't help
matters for the Americans.

In the late 70's (or was it the early 80's?) an Eastern
region designer developed a new runner design which used
a wood body, and had a removable steel blade. While it
wasn't class legal, it was apparent this new design could
be a logical successor to the T, using readily available
steel. After a trial period, the "insert" runner was added
to the specifications. While this was supposed to be an
alternative to the T, it had different dimensions than the
T (or any other runner for that matter), so was actually
an entirely new runner design. Instead of simplifying the
runner designs, the new insert actually complicated the
situation. Why the insert didn't have the same dimension
as the "T" is one of those baffling mysteries of the universe.

As runners proliferated, it was becoming obvious that the
class needed to simplify things. There has been talk of
eliminating runners from the specs for many years, but so
far the only thing that has been eliminated was the "file
stock" runners. This was an easy decision because not
many sailors owned them. There was also an effort to
eliminate "T" runners a few years ago. This was defeated
because many sailors own them, and they do provide a
performance benefit under some conditions.

And that's where we are today. There has been talk of
allowing 36" plate runners. There is still talk of trying
to eliminate the T's. There is more talk of changing the
insert specs to allow the same dimensions as T's. Any of
these choices would add to the number of runners. To counter
this, there is talk of restricting the number of runners a
sailor may use during a given season. Talk, talk, talk,
that's what DN sailors do best...

Rules

257

Posted by: David Wilkins on April 29, 2002 at 11:59:33:

In Reply to: Re: One last plate runner question... the "stupid crown" snow plate saga posted by Paul Goodwin on April 10, 2002 at 06:57:17:

I'm wondering if this posting will be seen before fall?

I'm looking for a "Dummies Guide to DN Rules" and can't find it.

In Maine we just had our spring CIBC meeting at Doug Raymonds' house and shop. There was a well attended informational meeting in his shop regarding runner sharpening, how to and what's fast. Camber, lead-in, exhaust, angle and finish etc. were explained well. But...we ran out of time (or I missed it) just when I really needed the proper explanation of what is allowed for sharpening, especially the lead-in area.
Please don't recite to me the text in the current yearbook. I'd like an explanation of an ideal section draw parrallel to the ice at 1/2" above the ice. Are the sharpening rules different for plates and inserts? I'm not sure I understand rules E 1 h or E 9 any more.

I know there's been discussion about rewriting the rules. I also know there was disagreement about the meaning of these rules at our meeting. Safety being their intent and fair play hopefully following, so how 'bout some feedback.

David Wilkins
US 5065

258

Posted by: Paul Goodwin on April 30, 2002 at 12:40:29:

In Reply to: Re: One last plate runner question... sharpening rules posted by David Wilkins on April 29, 2002 at 11:59:33:

You have asked about one of the most difficult to understand
specs in the DN class. I know there is no consensus among the
sailors and builders what these rules are trying to say, and
I doubt if you could get a consensus even among the Technical
Committee. You also asked "I'd like an explanation of an ideal
section draw parrallel to the ice at 1/2" above the ice".
I'll try to answer that at the end of the expanation of the
two specs.

Note: any answers I give here are my own opinion, not official
interpretations.

I have made it my business to try to understand the specs, and
help clarify or change them when they aren't clear. Both of
these specs are designed to prevent sharp leading edges on
runners which might cut a sailor in a collision. I think the
meaning of E.1.h is clear (although others may disagree with
my interpretation). But E.9 is crying out for help, but keep
in mind it was written before the introduction of insert runners.

Let's start with the easy one. E.1.h applies only to plate
runners. It should probably be extended to include wood body
runners, but right now it doesn't. E.1.h prevents a "sharp"
leading edge by requiring the thickness of the steel plate to
reach the minimum thickness within 3/8" of the leading edge.
The "normal tangent" wording means that at any point along the
leading edge, you measure back 3/8" at 90 degress to the edge
and measure the thickness - it must be at least minimum
thickness (0.23"). This wording also makes it easy to measure:
a gauge can be made with slot that measures 0.23" wide and 3/8"
deep, this guage must not be able to fit over the leading edge
at any point above the sharpened ice contact edge (or just
barely fit).

Now on to E.9. This spec applies to all runners, and puts
additional restrictions on the leading edge profile. I think
the first sentence is clear, and I'd be happy to explain if
it isn't. I find the second sentence the most confusing.
The "included angle of not less than 75 degrees" is easy to
understand, but where? Since the sentence starts with "The
leading edge of the runners" it implies that the 75 degrees
will apply to the part of the runner edge above the ice.
But the sentence ends with "up to a point not exceeding 3/4"
above the ice", which implies the 75 degrees will apply to
the part of the runner edge below 3/4". Very confusing.
I drew this up and it seems the "75 degree included angle"
and the "minimum thickness within 3/8" of the leading edge"
don't work well together, so it makes sense that the 75
degree angle is the minimum angle for the ice contact edge.
I would like to see this changed so it makes sense.

The next sentence in E.9 applies to the forward-most part of
the leading edge ("the edge of the compulsory 5/8" minimum
profile radius"). Since this part of the leading edge is
very likely to contact a person in a collision, it is the
"dullest" part of the spec. The edge of the 5/8" must not be
sharper than a 1/8" radius. This applies to all runners, but
wood body runners are usually thick where the 5/8" radius
occurs, and the 1/8" radius has little meaning. On a Sarns
bullnose, the 5/8" radius is on the aluminum stiffener, and
again has little bearing (although I suppose the 1/8" radius
should still apply to the edges of the aluminum stiffener).
However on some plate runners, the 1/4" plate is exposed at
the leading edge, and some wood body runners are tapered in
the front. It is these runners which are most affected by
the spec in this sentence. All along the 5/8" radius, the
edge cannot be sharper than 1/8" radius. This seems clear
to me, let me know if there is still confusion.

In the next sentence, "the remaining portion of the leading
edge" refers to the part of the leading edge below the 5/8"
radius and above the ice (or at least down to within 1/2"
above the ice). This section cannot be sharpened to less
than 1/16" radius. This is significantly sharper than 1/8",
but still considered dull enough to be safe.

For both the 1/8" and 1/16" radius portions, the radii must
be "faired" (blended) into the full thickness of the plate.
Keep in mind that with this fairing, you must still meet
the requirements of E.1.h., meaning the fairing must not
reduce the thickness to below the minimum beyond 3/8" from
the edge.

The last sentence refers again to "1/4 inch steel plate runners",
but should really apply to all runners. You can't taper the
blade below the minimum thickness as you approach the sharpened
edge. This was added when some builders had the silly idea
that the plate could be less than 0.23" thick near the bottom
as long as it met the minimum thickness higher up. But
"minimum thickness" is the minimum, and it applies to the
entire runner (with the exceptions listed in E.1.h and
earlier in E.9).

Now back to your real question, what is the ideal cross section
1/2" above the ice. You picked an interesting spot to ask
about, because it is near where there is a transition between
the "leading edge" and the "sharpened edge". Generally speaking
this point is off the ice and should be very dull. At 1/2"
above the ice my runners are actually fully into the leading
edge radius, and I don't taper my runners at the leading edge.
Some people will say you can get better performance by tapering
or sharpening the leading edge to penetrate snow (especially
crusty snow). As soon as you begin any tapering, you open
a whole new "can of worms" as far as specs are concerned.
I put a 90 degree edge on my runners, then blend it into a
1/8" radius on the leading edge. This transition is about
3/8" off the ice on most my runners. To me this is an "ideal"
edge profile since it offers no controversy and is easy for
the measurement committee to check. I won't risk accidentally
making an expensive set of runners illegal, or possibly losing
a regatta for a small gain in performance. To me the bigger
gains are to be made in learning to sail fast and eliminating
tactical mistakes on the race course...

Insert vs Plate Runners

675

Posted by: Konrad on April 05, 2002 at 19:41:45:

After reading the thread just below this one, can someone give the basics as to benefits/drawbacks of each type of runner? I guess I always thought that inserts were an old school technology, but if people are currently building them, there must be more to inserts than I'm aware of. Inserts look to be lighter, but perhaps they flex more? Do certain conditions warrant one type over the other?

681

Posted by: Paul Goodwin on April 08, 2002 at 10:00:17:

In Reply to: Instert runners vs. plate steel runners posted by Konrad on April 05, 2002 at 19:41:45:

First the basics, the longer and flatter a runner is, the faster
it will go, and the slower it will turn and accelerate. This is
a bit of a generalization, but holds true in most cases.

Another basic, when the snow is deep enough that an insert runner
is dragging it's body through the snow, it's time to switch to
plates.

If snow is not a problem, I always choose inserts first.
Inserts are almost always faster than plates on good ice.
The only time I would choose plates is in really light wind
and a short course, when plate runners let you tack on shifts
without losing much speed, and plates have a little less drag
at low speeds.

If the snow is more than 1-1/2" deep, then it's usually time
to use plates.

When the ice is mostly clear, but there are occasional deep
drifts, then the choice is less clear. These are conditions
when you'll see both inserts and plates on the starting line
at the same time. All you can do is try your particular runners
and see which set is the fastest for the given conditions.
In light wind a boat will sometimes stop dead in it's tracks
if you hit a drift using inserts. But when the wind comes up,
you can blast through those same drifts with inserts and the
better top end pays off.

Plate Advantages

253Posted by: Geoff Sobering on April 08, 2002 at 21:46:47:

[OK, it's probably not the final question I'll every ask about plate runners, but...]

Are there any circumstances when the older-style plate runners (the ones with the more gradual angle toward the ice) have an advantage over the "Bullnose" profile?

254

Posted by: P. Ashley on April 09, 2002 at 01:17:51:

In Reply to: One last plate runner question... posted by Geoff Sobering on April 08, 2002 at 21:46:47:

This Spring there was a "Beanpot Regatta" at Lake Wentworth, N.H..
(See posting under regatta results on IDNIYRA.ORG)
I was using bullnose runners and suffered against the old "aligator" Sarns runners. [The bullnose seem to "ram" into the snow-ice] The aligators seemed to do better maybe as Paul has said about the shorter runners tacking with less loss on a short course.
I feel that "aligators" are safer when there are cracks on the course and use one for steering at that time. I feel also that they may rise over hard snow mounds when the snow is too deep for inserts. [bullnose doing more of a ramming job]
It would be great to hear some comments about this from Western sailors!
Oh, bye the way, we all had a great time that day due primarily from the loss of mental fatigue usually associated with choosing runner type. Someday???? 1/4 in. plates for the whole class????
Keep smiling ,
Pete

255

Posted by: John Davenport US4961 on April 09, 2002 at 14:06:05:

In Reply to: Re: One last plate runner question... posted by P. Ashley on April 09, 2002 at 01:17:51:

There definitely can be a difference between the old and new profile of Sarns runners. But there is also the cross-sectional lead-in to be considered. Sarns runners have the edge broken, but it is permissible under the rules to go much further. It is possible that the lead-in edge has more to do with it. That being said, I remember the last race in the Gold fleet at the 1997 NA’s in Detroit. I was sailing Silver so I could see what was going on in the Gold. Ron put on a set of these absolutely minimum length with radical lead-in and swept back end like an IOR boat runners I had ever seen. Very short edge with this geometry. He did and incredible “Horizon Job” on the fleet in that race and it was a Gold Cup year, so all the best Europeans were in the race with him. I went over and talked to him and he said that he rarely can get them to go…he did that day. I made a set that next summer and I have only been able to get them to really go once. They were really the ticket that day in deep drifts. Otherwise the edge is too short to get the boat up on top. They are sometimes noisy even with good alignment (crunchy slow). It may be that the ice must be very hard so they don’t dig in. So I am building a longer set but they will still have a nice lead-in like the older Sarns runner but with a finer front edge. I believe they will probably be better in the all-around condition. We will see!

256

Posted by: Paul Goodwin on April 10, 2002 at 06:57:17:

In Reply to: Re: One last plate runner question... posted by John Davenport US4961 on April 09, 2002 at 14:06:05:

I remember those runners! Actually I have a set too,
except mine weren't completed for that regatta. We cut
out the steel at the same time, but Ron finished his
three years before I did.

Ron and I made those runners out of standard "Sarn's"
steel (SAE 1060) and they were modeled after a set of
Jan Gougeon's runners. Jan calls these his "stupid
crown" runners, with so much crown they are (you
guessed it) -- stupid. With these runners, there
are times when Jan can sail all over the lake while
the rest of us stand by watching. Their particular
niche is when there is hard crusty snow on the ice
and light wind. They don't have much top end, but
they keep going when other runners grind to a stop.

After building our own "stupid crown" runners, it was
apparent they really were a niche runner, with hardly
any practical use on the race course. When the
conditions get that bad, the race committee just
doesn't start a race. Ron changed the crown to
something less radical, and these became his "snow
plates", which he has used successfully in a couple
different regattas. These are fairly useful runners,
and work well when there is crusty snow, especially
if the wind is light. They also work on good ice
when the wind is really light and/or the course is
short (recall my previous comments about short runners).

Since they proved their worth at that NA's, we
subsequently built a set out of 440C (the 1060 ones
always seemed to be rusty when you needed them),
and they have found a home in my limited quiver of
runners. They require a little different technique
to sail compared to other runners, but they may be
as (or more) useful than standard Sarn's plates.
The runners are minimum length, have composite (wood
and carbon) stiffeners, and are light weight. The
edge of the lead-in is very similar to a Sarn's
runner, with essentially a full round contour. The
lead-in angle isn't really that radical either (less
raked than Sarn's "alligators"), but I love John's
description: "absolutely minimum length with radical
lead-in and swept back end like an IOR boat" -- it's
almost poetic!

These are not runners I would tell sailors to rush
out and add to their collection because of the few
times when they might be useful. But, like angle
"slushies", they can be fun to sail and experiment
with.

Just as a reference, here is my current quiver of
runners (roughly in order of usefulness):
1) 3/16" x 36" 440C inserts (2)
2) 1/4" x 36" 440C inserts (2)
3) 440C snow plates (3)
4) Sarn's bullnose (3)
5) stainless steel angles (2)

My 3/16" inserts have no stiffeners, and I don't
like the amount of flex they have when it's windy.
The reason I like the 1/4" inserts is because they
are stiff, strong, and heavy (for windy conditions).

If I had no runners right now, I would start with a
pair of 3/16" x 36" 440C inserts with removable (and
heavy) stiffeners and a minimum length plate for
steering. I think these would cover more than 80%
of racing conditions in the US. Next I might add a
pair of 26" snow plates, or possibly Sarn's 30"
bullnose -- the jury is still out on this one.
With these two sets, the only condition that a
person would be really suffering is when the ice
gets soft, then you'll wish you had those 1/4"
inserts or angles (especially if you weigh over
200 lb like I do).

Alignment

291

Posted by: Steve on January 24, 2003 at 09:58:22:

What is the best way to align runners? I had the board detached from the hull, mounted the runners and placed then on some carpeting as not to dull them. If I pivot the board back and forth the tips go in and out. Common sense tells me the best way would be to have someone sit in the boat and then check alignment. Is there a better way? Is a tape measure good enough? I had them aligned within 1/64" before with no load in the boat.

292

Posted by: Bob Rast DN 1313 on January 24, 2003 at 19:54:59:

In Reply to: Runner alignment posted by Steve on January 24, 2003 at 09:58:22:

I’m sure you will get several ideas after this post. I use a dial indicator which runs on the edges of the runners. First I clamp the plank upside down on a saw horse made with a 8' 4x4. Level the chocks side to side parallel to the length of the plank, then level fore and aft. Insert runners and put level on the sharpened edge and also plumb vertically. I can usually get them within a few .ooo.
You might try using some angle aligners with the runners on the plank and boat set up. You can find plans in the reprints.
Another method uses a rifle scope and a stick which is marked with the runner track and then moved 10 to 20 feet in front of the plank. Some guys do this on the ice . I do it in the basement with the plank clamped upside down. Produces pretty good results although my boat speed doesn’t show it. Ron Sherry uses the triangles on the ice method and seems to work for him.

851

Posted by: Geoff Sobering on February 02, 2004 at 12:21:08:

In Reply to: DN runner alignment technique? posted by Mark Barner on January 31, 2004 at 18:11:23:

For the life of me I can't find an on-line description of the process. I believe the cannonical write-up is in "Think Ice".

The basic idea is to use distance to magnify a small displacement of the edge on a runner. An earlier post has a crude diagram that might help:
http://cerebus.winsite.com/laser/DNboard/mesgConst/846.html

Using a scope instead of a laser means you're looking at the movement of the "virtual spot" provided by the cross-hairs instead of the real spot projected by the laser.

There are three basic things you can use this technique to do:
1) Align chocks to be parallel
2) Shim all your runners to be the same
3) Check for wobbles in the edge of a runner

For 1) you setup a target 10-30 feet away with two spots exactly the width of your runners. Mount your plank parallel to the target and deflect it however much you want. Mount a runner in one chock and sight it onto it's target spot. Move the runner to the other chock and sight the other spot. Adjust the chock so the cross-hairs fall on the target spot and the two chocks are parallel.

For 2) and 3) you mount a spare chock in a vise and point it at a single target spot. For 2), mount your "standard" port runner in the chock and adjust the chock so the cross-hairs line up with the mark. Now take all your port runners and shim them in the chock so they all line up the same. For 3), mount a runner in the chock and slide the scope along the edge looking for wobbles in the edge; then grind the edge straight.

I hope this helps a bit. I'd suggest getting a copy of "Think Ice". I also know there have been some discussions of the technique either here or on the Yahoo! Iceboating group (but I couldn't find them in a quick scan...)

347

Posted by: K Smith on November 07, 2003 at 01:57:38:

I was going to refer to the board to guide a newbie in all the methods of aligning chocks and runners. Its all FOLKLORE! I know of many methods: Glued chocks with triangles vs glued chocks with dial indicator vs dialed in with dial indicator on the boat and shim tape vs adjustable chocks and triangles vs adjustable chocks with an adjustment screw vs adjustable chocks with a gun sight vs Kieffer lying on his belly using a gunsite on the ice.

What is your preferred methos of runner and chock alignment? I'd like to build a record here...

348

Posted by: Jane on November 07, 2003 at 13:32:15:

In Reply to: Chock and runner alignment posted by K Smith on November 07, 2003 at 01:57:38:

"Folklore" is an excellent label for runner alignment.

I've seen guys loosen up the chock bolts on the ice, give the boat a push, tighten the bolts, and win the next race. Low tech, but effective.

Precise alignment is most critical with long runners at low speed on soft ice. Who know's what happens when you're actually under sailing load? We all think we know the plank deflecton, degree vs. verticle of the runners, but runner crown and angle are of equal significance.
And the mast and sail combination are even more critical.

But finally, the most important factor is the skill of the "nut on the tiller", i.e., the skipper.

349

Posted by: Andre Baby on November 07, 2003 at 16:00:35:

In Reply to: Re: Chock and runner alignment posted by Jane on November 07, 2003 at 13:32:15:

Here is my bit of folklore.
After having tried triangles on the ice, gunsight a la Kieffer,upside down compressed plank in the workshop with dial indicator, Jeff Kent method of boat on sawhorses on the ice and scoping the runners from underneath (Tricky),Here is THe method ,In the comfort of your basement :

Buy two 14 ft x 2ft lengths of arborite or other slippery material
Buy 2 x 12ft x4inches wide x1/4 inch thick machined aluminum flat bars
Machine a 90 degree groove dead center down each bar
Glue an arborite backing down the underside of the bars
Set the bars on the arborite with lots of WD 40.
Set up the boat and fit the runners to be checked inside the grooves.
put the front runner on a 1/4 inch plate and piece of arborite, so that all runners are on the same plane.
Put 300 pounds of iron bars (10 x 30 # )iinside the cockpit.
Flex the boat and plank up and down lighltly a few times and see the runners and bars work sideways on the slippery arborite.
Measure the distance in millimeters between the bars at the front and at the rear extremities of the bars.
Shim runners appropriately,untill you get + - 1 mm, and forget about them for one season at least.Sounds laborious , but repeat performances are easy.
Apart from actual runner adjustment while sailing , which no one has yet devised a safe method of doing,I have found that this is the method ,along with renting a hockey rink,that best simulates ice conditions with the boat under load.
Have fun,
Andre Baby KC 4360

350

Posted by: George on November 11, 2003 at 10:52:29:

In Reply to: Chock and runner alignment posted by K Smith on November 07, 2003 at 01:57:38:

As long as you are building a record...here goes...

I'm sure this method has some technical flaws but it works for me....someone has been sailing recreationally but is just getting into racing.

I use two 4’ lengths of angle aluminum. The thicker the better.

I use two clamps to clamp one angle to each runner. I orient them horizontally and so that they are just above the ice/ground and one edge protrudes about an inch forward of the leading edge of the runner. They then extend 4 feet aft. Weight the boat or tension the rig. Measure at each end of the aluminum with a tape measure. Clearly you want the measurements to be the same. This assumes, of course, that your runners are straight to begin with.

The principle here is that any difference in alignment angle becomes more apparent the longer the side. At 4 feet, you know very quickly whether you have a parallelogram / square or a trapezoid.

With just a decent tape measure you can easily measure to 1/32 of an inch for each side. Using some basic trig, I figured that 1/32 represents 0.037301935 of a degree at a length of 4 feet. That means you are within approx. 2' ( 1/30th of a degree ) of parallel. It cost me $14 in aluminum.

352

Posted by: Geoff S. on November 11, 2003 at 16:57:32:

In Reply to: Re: Chock and runner alignment posted by George on November 11, 2003 at 10:53:51:

Interesting.

How to you align the aluminum on the runner fore-aft?

In order to get a good measurement you need to make sure the two angles are the same length, and also positioned the same fore-aft relative to the runner. I'd think a scribed mark on the outside of each angle aligned with the center of the pivot bolt would be enough.

It would be interesting to do the error analysis for error created by unequal lengths, and the error caused by misalignment relative to the runners. My gut feeling is that neither would be that big a deal.

You are, of course, assuming the alumium is perfectly straight. Any bend would introduce a direct error to the measurement. However, it should also be easy to check for it, by reversing the two angles fore-aft and swapping sides. If the front and rear measurements were identical before the swap, they should be off by twice the error in the straightness of the angles after the swap (right?).

353

Posted by: George on November 11, 2003 at 17:25:40:

In Reply to: Re: Chock and runner alignment posted by Geoff S. on November 11, 2003 at 16:57:32:

For and aft is not that critical. If you misalign fore and aft on the aluminum angles by 1/4 inch, at 8' between the runners, the error you introduce to your measurement is only .000326 of an inch by my calculations (the good old pythagorean theorem).

You are correct about the angles, they have to be straight to begin with and you have to make sure you don't bend them with measuring tape tension.

354

Posted by: mark kiefer on November 12, 2003 at 09:29:08:

In Reply to: Chock and runner alignment posted by K Smith on November 07, 2003 at 01:57:38:

I am almost honored to have the cumbersome process of laying on the ice and using a rifle telescopic sight to verify runner alignment carrying some reference to me. This is a process which originated in sighting in guns on fighter aircraft... at least I think that's one way it was once done (during World War One).

The advantage of the system is this: you can carry all the technology in your toolkit, (very portable, very cheap), disadvantages are this: you're laying on the ice for a while, it's wet, cold on the anatomy, and it aint' really quick.

When carried to it's most absurd level here's the process, with glued chocks presumed to be parallel.

- use a hockey rink setting the boat up with the plank centered over the red (goal line) and indoors is better, er warmer in my part of the world. (they're often vacant during school hours)

- using a stick (8' 2" of 1x2 with a runner cut taken under the bolt holes, set up on the opposite goal line ~ 176 feet away.

- Verify you're set up along the centerline of the boat using a standard carpenter's square... that is using string/fishing line, tight between the center line of your runner cut/reference stick, although the goal crease is a pretty accurate centering/squaring reference.

- using one set of runners at a shim the runners on the load bearing inside of the runner, until the cross hairs line up (EXACTLY), with patience, you can shim to an alignment of about +/- 1 pencil line at 175 feet. Doing the math, It works out to parallel along the running length (say center 18 on the ice inches of runner) at about +/- a millionth of an inch. or that order of magnitude.

- slight process modifications (seen in use by some other western region sailors) is sighting on a lake, using a boatlift, watertower, tree, picture window as a reference at a miles distance...as your reference

- Caution, if you think you can accurately align to this level of precision, test by holding scope on the running edge, sighted on the cut line, and hold the other hand (ungloved) on either the front or back inside portion of chock, your body heat transferring to the chock changes the alignment. :)

- the real advangage (theoretically) is a sailor can have all the runners lined up as parallel as can any other means for about 30 bucks in total system costs)

- disadvantages, to get a set of runners aligned "perfectly" may take an hour a set. or if you're in the gold fleet - a weeks labor.

- I have great respect for the triangle alignment system like Ron Sherry and others use... it's really fast & simple, and given the success of people using it (you can check alignment prior to each start , in less than 5 minutes time)

Think Ice

4695

355

Posted by: Paul Goodwin on November 12, 2003 at 11:31:23:

In Reply to: Chock and runner alignment posted by K Smith on November 07, 2003 at 01:57:38:

Having tried many different methods:
- adjustable vs bonded chocks
- gun scopes
- laser sights
- wood sticks with notches
- sticks with dial indicator
- tape measure
- pushing the boat on smooth ice to "self-align" loose chocks

--- I have settled in to what HAS to be the ABSOLUTE BEST system
for runner alignment

Of course that is bulls***t, next year I may have a NEW BEST
system, just like I a couple years ago when I had a different
BEST system.

However I can spew some of my thoughts:

1) I'm now in favor of bonded chocks so that I don't have to
worry about my chocks getting out of alignment - short of
actually bending a chock. Ron Sherry makes a good point that
chocks can be bent, and there is no way to correct for it if
the chocks are bonded. I've decided it's worth the risk (I'll
change my mind after the first time I bend a chock at a regatta).

2) The dial indicator method is inferior to using the "triangle"
plate method. Two reasons for this:
a) The distance between the runners will change with plank
deflection. If the plank moves AT ALL, the indicated reading
will have an error. This is not much of a problem in the confines
of a workshop, but becomes a real problem outdoors.
b) the dial indicator can only correct for parallel, and allows
both runners to be at an angle to the boat, causing the boat to
"crab" (sail at a fixed angle to the direction of travel). This
is like having a mainsheet traveler adjusted to weather on tack,
and to the lee on the other tack.

-- To build a set of simple triangle alignment plates, see the
article "Runner Aligners - by Elmer Millenbach" on the IDNIYRA
website (www.idniyra.org). Ot you can contact Ron Sherry to
buy a set of triangle aligners.

3) Laser sights are better then gun scopes, since you don't have
to look through the scope with your cheek running down the edge
of the runner. The laser sights are just as cheap as scopes
these days (around $20).

4) Recreational sailors can get by just fine using a tape measure
and carpenters square.

5) It's best to have all your runners lined up at the start of
the season (by shimming or other method), requiring no adjustment
of the chocks when changing runners.

****************************************
For the record, here's my preferred method for 2001/2/3/4:

1) Bonded chocks using the old Gougeon triangle method (see
the article "Iceboat Runner Blades - 3 steps to help you get
the most out of yours this season" on the IDNYRA website -
www.idniyra.org). This gets the chocks lined up on the plank
(square to the plank, parallel to each other, and runner vertical
angle set properly).

2) Each individual runner edge true to the chock. Here is how
I do this:
a) Have a spare chock mounted to a board.
b) Clamp the board to the workbench.
c) Put your best runner in the chock and set the edge horizontal.
d) Using a laser sight with a 1/32" groove in the bottom
(contacting the edge in 2 places about 1-1/2" apart), project
the beam on a far wall of the shop and align with a vertical mark.
e) Run the laser from end to end on the edge. The laser should
stay lined up with the vertical line on the wall. If it wanders
from side to side, then the edge isn't straight (this was really
your best runner???).
f) Swap out your best runner for your second best. Check for
straightness. Hopefully this runner lines up perfectly with the
line on the wall, just like the first runner.
g) Check several (or all) runners. The group which does the best
job of pointing at the same line is your "baseline". This will
reduce the amount of adjustment, and likely provide the best
overall alignment. Note: Sarn's runners are generally very
straight and are usually a good baseline.
h) Now, check each runner one at a time, and shim them so that
they all point at the line. Be careful not to move the chock
when changing runners. I don't shim my runners because they
fit the chock too tightly (no room for shims). So, I sharpen
each runner to align them. Somewhat tedious the first time (most
of my runner were very close to start with), but not really
much additional work after that.
i) Finish up by using a system to measure the runner alignement
on the boat. If everything went smoothly, all your runners
should line up. If you find that all runners are off the same
way, then the chocks are not bonded in the proper position
(you'll have to remove one or both and re-glue). If only one
or two runner don't line up, then adjust each runner as necessary.

***********************************

If a runner edge isn't straight (the laser wanders from side to
side as you sweep along the edge), then you should definitely
straighten it out. You can use the laser to determine how the
edge wanders, and remove a little material from the edge on one
side or the other in small local spots. Do this carefully in
small increments until the edge becomes true. Now you need to
recheck the crown and make corrections. Go back and forth
between crown and straightness until both are perfect. I found
that after correcting for straightness, I was able to "dial-in"
the crown on a runner that had given me problems for years.

Follow this plan and gain lightyears on your competition...

p.s. I plan on bringing most of my alignment equipment to the
Jamboree this weekend (11/14 - 11/16, 2003)

356

Posted by: Geoff S on November 13, 2003 at 10:45:38:

In Reply to: Re: Chock and runner alignment posted by Paul Goodwin on November 12, 2003 at 11:31:23:

> d) Using a laser sight with a 1/32" groove in the bottom
> (contacting the edge in 2 places about 1-1/2" apart), project
> the beam on a far wall of the shop and align with a vertical mark.

I've always wondered about this step. I'm visualizing the scope/laser mounted to a block with a shallow v-grove in the side opposite to the scope. It would seem that the block/scope could tip from side to side as it's slid down the edge, mimicking the effect of a wavy edge.

Am I missing something about the geometry, or is there some way to keep this from happening?

Cheers,

Geoff S.

357

Posted by: Paul Goodwin on November 13, 2003 at 17:25:21:

In Reply to: Re: Chock and runner alignment posted by Geoff S on November 13, 2003 at 10:45:38:

This is a basic problem with the setup I'm using right now,
and is the only thing holding me back from making some laser
thingies to sell. My thoughts are running towards a guide
that runs along the blade or body that keeps the laser from
tilting. However this only works if the surface is truly
parallel to the edge. A more recent thought is to have an
articulating guide that touches the body in the vicinity of
the mounting bolt, and doesn't traverse with the laser - much
more difficult to engineer, let alone build.

But here is the good news: I thought I was pretty good at
sharpening runners, and every one of my runners was crooked
according to the laser. Subsequent to the edge straightening
and aligning process, there was far less "wander" in my edges.
So even though there is some skill required to keep the laser
straight up and down, the net result is better than not using
the laser.

Paul Goodwin - DN US46

358

Posted by: Scott Crothers on November 13, 2003 at 22:19:50:

In Reply to: Re: Chock and runner alignment posted by Paul Goodwin on November 13, 2003 at 17:25:21:

Paul (and others)

How about a laser mounting plate,
grooved on the bottom with clearance
through the center so only two points
touch the blade edge, counterbalanced
with outriggers at a 45 degree (or so)
angle downward to keep the laser sitting
straight on the blade without touching
any other surface to throw off the reading?

Looking from rear of blade, edge up.

Laser
on
top Side view, contact area
________ ___________
//___/\____\\ /__-------__\
// /\ \\ |
-0- || -0- counterbalance -0-
||
|| blade edge centered in groove

Hopefully this diagram holds together...
Scott

359

Posted by: Andre Baby on November 14, 2003 at 11:16:09:

In Reply to: Re: Chock and runner alignment posted by Paul Goodwin on November 12, 2003 at 11:31:23:

Comment to Paul Goodwin's method;
When you are aligning all runners to the baseline , on the separate test chock, how are you assured that the chocks on your plank will be identical to the test chock ?.
On the contrary, I have found that there is quite a lot of variance in width between my Hamel long chocks,sometimes even between fore and aft of the same chock.

360

Posted by: Ken Smith on November 15, 2003 at 10:30:26:

In Reply to: Re: Chock and runner alignment posted by Andre Baby on November 14, 2003 at 11:16:09:

Runners:

I use a slight variation of Paul's to get all runners exactly aligned to each other. I clamp a chock to the table and sight with a gun scope on a line at the other end of the shop. Each gun scope mount is clamped to a little hunk of lead with a grove in it (tap with chisel). THe mounts are about three inches apart. I sight on a pink string hanging on the far wall with a weight on the bottom. The scope's vertical cross hair overlying the string ensures the scope is straight. Sliding the scope fore and aft checks straightness, aligning the table-chock to the string with the "reference" runner and checking the edge for another runner checks runner edge alignment. [Andre: All the runners are the same in the same chock. See below to get the plank's chocks aligned to parallel using two runners]

It was a long session (weeks) to get all the runners identical, but once done, I can put any runer on either side and be assured they are as aligned as the chocks are.

When one must gring a runner, runner grinding goes in a loop: Check profile, check straightness, grind, check sharpness, check profile, check straightness, ... Tools: spare chock, Light box, rifle scope, belt sanding table. THat is why stones are used for sharpening. Gringding is drudgery.

Chocks on the plank:

I glue one down using a BIG equilateral triangle made with aluminum angle and a 1"square aluminum tube set into the chock. The triangle makes the chock square to the plank. The chock is shimmed and glued so the chock is vertical with the plank deflected as on the boat with me and a 30 pound weight. The other side is shimmed to have a flat surface at the same time. The chocks are held vertically and epoxy fills the gaps between the top of the chock and the plank.

The side being glued is preped for gluing and "wet sanded" with epoxy. The other side has a layer of plastic wrap between the epoxy and the chock. This leaves a flat pad at the correct angle on the plank for vertical chock sides.

Step two consistes of setting chock two in place. Alignment between the chocks is checked with a runner in each chock. THe runner is angled and plank deflected as if me-in-the-boat... With the chock preped for gluing and the epoxy wet, the chock is put in place and aligned, using a dial indicator on the edge and a rod to the other runner's edge. Centered over the bolt and a fixed distance fore and aft. Once perfect, let it cure.

I am of the glued-chock school. If a chock gets bent (happened when a runner went into a crack once), it is spare plank time. I have two complete boats with all parts interchangable.

Ken SMith
DN 4137

361

Posted by: Jeff Brown on November 15, 2003 at 13:04:19:

In Reply to: Re: Chock and runner alignment posted by Ken Smith on November 15, 2003 at 10:30:26:

I am reading all of this with great detail to understand how to achieve the best alignments. I do not pretend to know what I am talking about here as I am very new to this DN experience.
I have built/aligned my boat using many of the same methods as mentioned, suggested and learned here.

I like Ken's method for sliding the gun scope and keeping the vertical crosshairs lined with the target plum line. That keeps the scope aligned.
I did this to check both rear runners simultaneously, mounted to chocks, plank deflected and targets as 2 corresponding plumb lines set to the cut width of runners.

In my shop, my plank was mounted upside down and deflected, probably not as the same as correctly weighted from above with sailor, hull +30lbs.
However, the plank crown deflection was the same measurable amount.
Now, when I slide the scope along each runner, the "drift" of the scopes vertical crosshairs to plumb lines was within the thickness of plumb line at 25ft distance and scope magnification. So I switched the plumb lines to 400# sailmaker string and got it even closer.
This was how I also glued/bolted the chocks to the plank. First chock was set squared to the plank as described with large triangle square, the other was fudged in using the above description with the runners in the chocks. I used the best runners for my base line setup.
Other runners are now shimmed to meet the same set up tolerances.

My method for this set up may not be like others have tried, but it worked and has been checked on ice using other methods and has shown to be accurate. One thing about my set up is that I am achieving both runner and chock alignment together during chock assembly.

I want to do the same setup with the plank mounted to the hull and weighted as recommended, then target the 2 plumb lines as I described. I'll have to hold the scope upside down and lay on my belly with the boat on saw horses just inside the chocks.

About my scope. I am using a simple gun scope with adjustable crosshairs. Be careful about that setting. I made a delrin block 3" long with 90 deg groove, 1/8" deep for the runner slide rest. I forgot how I calibrated the groove to the crosshair adjustment, but some how I did. I think I laid a fine string in the groove, extended out to a target plumb line, then dialed the crosshairs to the plumb line. Perhaps crude, but close.

About lasers. This I know a great deal about as I worked in a laser lab for 5 years and studied the effects of columnation of beam paths and target spot sizes.
Most laser pointers do not hold a columnated beam. That means that the farther you shoot your target, the larger the spot size. Spots at 30 feet can be as large as 1". Also, the beam alignment is never parallel to the diode casing (internal factory housing) nor is this diode casing parallel to the outside pen casing. Be careful to make assumptions with this equipment. Just roll a laser pointer on a table while shooting a wall and you will see what I mean.
I know any measuring equipment, if used with this understanding about deviation, you can expect deviation to be the same with any setup. Just be mindful about it.
I prefer the scopes myself as the crosshairs are another source reference.

Jeff Brown
US 5232

362

Posted by: Bob Rast on November 15, 2003 at 20:51:01:

In Reply to: Re: Chock and runner alignment posted by Ken Smith on November 15, 2003 at 10:30:26:

Don’t forget to zero in your Scope? To check if your scope is aiming straight , Take a paper clip or wire and bend it so it will fit your runner thickness with a straight section straight up from your runner edge Look through your scope from the rear of your straightest runner you shoud see the end of your runner and the paper clip pointing up in your cross hair . If you are right or left of center, take off the cup on the top of the scope and turn screw 1 click and see which way it is going. You need to be right over the center or all your runners will be off. Here is a diagram

l
l
l
l l
l l
l l
Blade>

364

Posted by: Paul Goodwin on November 18, 2003 at 09:49:09:

In Reply to: Re: Chock and runner alignment posted by Andre Baby on November 14, 2003 at 11:16:09:

You can't assure that the chocks mounted on a plank are
identical to the test chock. However, the assumption is that
you will be able to align your chocks perfectly on the plank,
with complete disregard to the runner that will be mounted in
the chock. Then as long as each individual runner edge is
perfectly aligned to it's body (chock bearing surface), then
any two runners should be in alignment when put on the plank.
If the chocks you're using don't provide accurate and repeatable
mounting, that is a separate ussue.

Of course this isn't a perfect world, and I would also recommend
checking the actual alignment of each set of runners mounted on
the plank. After completing my edge straightening and alignment
program, I checked my runners mounted on the boat. I also swapped
runners from side to side and found that with some runner pairs,
the alignment was better one way or the other, and subsequently
marked them port and starboard. However all were close enough
that I didn't attempt to do any further alignment (shimming or
regrinding).

Paul Goodwin - US46

********************************
>> posted by Andre Baby 14 Nov 2003

In Reply to: Re: Chock and runner alignment posted by Paul Goodwin
on November 12, 2003 at 11:31:23

On the contrary, I have found that there is quite a lot of variance
in width between my Hamel long chocks,sometimes even between fore
and aft of the same chock.

365

Posted by: Paul Goodwin on November 18, 2003 at 10:15:22:

In Reply to: Re: Chock and runner alignment posted by Jeff Brown on November 15, 2003 at 13:04:19:

Jeff,

In my opinion you are using methods that will provide results
on par with the "best in class", pretty impressive for a newcomer
to the class.

Using two strings a runner width apart is a very good way to
set/check runner alignment. You still need to get one of the
chocks square to the plank first and then adjust the other
chock parallel to the first. The two strings alone will not
check for squareness. Of course, you covered this well by
using the big triangle to set the first chock. I'm just
repeating it for the benefit of other readers because it's
so important for correct alignment.

The lasers I've seen lately have gotten pretty good at
collimation (even at bargain prices), with $20 laser gun
sights projecting a beam width of 1/4"-3/8" at 30 feet.
I had a discussion at the Jamboree with a person who aligns
machinery for a living, and he doesn't think it's possible
to align better than 3/8" with a 3/8" beam, but it will
take a little more ruminating before I'm convinced it
applies to this situation. Of course, this would still
only be 3/8" deviation at 20-30 feet, creating a small
angular error. I've done my time in the lab calculating
accuracy, repeatability, etc for lab measurement set-ups.
I'm pretty happy with the laser rig I'm using now, and
confident in the results. I also know it can be improved,
so I'm keeping my mind open and "ear to the tracks".
In any case, I believe the simple laser jig I'm using has
improved the straightness of my runner edges significantly.

All the gun sight lasers that I've seen have adjustments
to bring the beam in line with the housing. I adjust this
by sighting down the runner edge by eye to align the edge
with a vetical line, then adjust the laser to also fall
on the line. Bob Rast's method using a paper clip should
also work, as well as your method with the string. All are
prone to some error, hard to say which method would have
the best accuracy.

I've done some of the math, and small deviations in beam
alignment have little effect on the runner edge (it
creates a small parallel error in alignment and a slight
curve in the edge).

I was never happy with a 90 degree groove in the guide
block for two reasons:
1) Not all runners are sharpened at a 90 degree angle.
2) Since you can't machine a true sharp notch, there will
be a radius at the bottom of the "V". The sharp edge of
the runner will contact this radius, and possibly affect
the alignment. On Ron Sherry's runner aligners, there is
a small groove at the bottom of the "V" to provide clearance
for the runner edge. Since the laser jig doesn't have to
support any weight, I think a simple narrow groove is better
than the "V".

I've had a rifle scope in my arsenal for several years, and
agree the cross-hairs are useful for keeping vertical
alignment. Weighing the pros and cons of the the rifle scope
vs laser, my rifle scope has moved from the "active tool" pile
to my museum of DN artifacts.

p.s. You're not the first person I've seen lying on the ground
(or ice for that matter) under a fully loaded DN looking through
a rifle scope - great intertainment.

Paul Goodwin - DN US46

366

Posted by: Ken Smith on November 18, 2003 at 10:27:11:

In Reply to: Re: Check your scope alignment posted by Bob Rast on November 15, 2003 at 20:51:01:

Bob:

The only problem I've encountered is because I put a drop of oil on the blade so the scope lides smoothly. My wife wonders how I got that nice straight black line on my right cheek, (peering throught he scope).

367

Posted by: Jeff Brown on November 18, 2003 at 22:25:49:

In Reply to: Re: Chock and runner alignment posted by Paul Goodwin on November 18, 2003 at 10:15:22:

Paul,
For only about $10,000 worth of laser lab equipment we can get that beam spot size down to a few millimeters!
I worked with laser components, fiber optics and lens pairing for several years at a medical research lab, it was a tedious job and would rather align my DN any day!
I'll look into those laser gun sight scope combos.

Thank you for your comments.

Jeff
US 5232

PS; I plan to slot the delrin slide block for runner clearance, good point.

374

Posted by: Geoff S. on November 26, 2003 at 18:49:07:

In Reply to: Re: Chock and runner alignment posted by Jeff Brown on November 18, 2003 at 22:25:49:

Here's a suggestion on how to make a laser aligner where the distance between the laser beam and the runner edge can be minimized (thus making the unit less sensitive to tilt error). The two tricky bits would be to get a good quality front-surface mirror, and getting it glued to the jig at exactly 45 degrees.

Another possibility is to use an optical converter that takes a circular beam and creates a fan (i.e. line). You could use this in the same way that Ken Smith uses the recicle line in the scope to keep the slider aligned with the marks. A quick search didn't turn up one of these devices, but I'm pretty sure they are available pretty inexpensively.

Cheers,

Geoff S.

Low-Error Laser Alignment Jig

375

Posted by: Paul Goodwin on November 28, 2003 at 14:11:50:

In Reply to: Re: Chock and runner alignment posted by Geoff S. on November 26, 2003 at 18:49:07:

Brilliant idea Geoff!!!!

I've been thinking on this for a while, and this concept never occured to me. Another plus to this idea is that the actual laser used may not be as critical - meaning I may be able to make an adapter that fits many different manufacturers lasers.

I think I have a source for cheap surplus first surface mirrors (used on dental mirrors).

Getting the 45deg angle should be a cinch also. I'll keep you posted on how I do...

As for the optical beam splitter, the ones I have seen are suprisingly expensive. Let me know if you find any cheap ones since I broke the one that attaches to the front of my laser level.

376

Posted by: Geoff S. on November 28, 2003 at 18:39:14:

In Reply to: Re: Chock and runner alignment posted by Paul Goodwin on November 28, 2003 at 14:11:50:

Actually, a perfect 45 degree angle isn't necessary if you allow for adjustment of the laser relative to the mirror. All you need is to get the laser beam that's projected over the edge to be "perfectly" parallel with the edge.

Edmund Scientific sells front-surface mirrors pretty cheap:
http://scientificsonline.com/product.asp?pn=3052324

377

Posted by: Jeff Brown on November 28, 2003 at 22:29:30:

In Reply to: Re: Chock and runner alignment posted by Paul Goodwin on November 28, 2003 at 14:11:50:

Hey guys, this is looking a lot like "laser lab tech"
I am interested and want to point you to a great resource I used when I built stuff like this.
Geoff's idea to get the beam closer to the runner edge is good, but adjustments need to be precision to get it right. This company has inexpensive 100/tpi screws with mounting hardware for only a few bucks each. You can get lots of ideas here too.

Check out all the goodies, not all expensive either at:

Thorlabs:

http://www.thorlabs.com/index.cfm

Front Surface Mirrors:

http://www.thorlabs.com/SelectGuide2.cfm?Guide=48&Section=2&Ref=8

$10-20

I'll be watching for progress and thinking about it too.

GO LASER OPTICS OR GO HOME!

Jeff Brown
US 5232

378

Posted by: Jeff Brown on November 28, 2003 at 22:48:36:

In Reply to: Re: Chock and runner alignment posted by Jeff Brown on November 28, 2003 at 22:29:30:

I had to search the local Thorlabs site for the screws.
I could not paste the link.

Enter search at Thorlabs website:

http://www.thorlabs.com/index.cfm

"fine adjustment screws"

This website is loaded.
I use an FAS125 with the brass sleeve insert nut for fine adjustemnts on a grinding machine I built for my Freeskate. These parts are worth it for only $6.00 a screw. Lots of sockets set screws as well, but you would need the tap. Get the FAS series with the brass inserts instead.

Jeff Brown

379

Posted by: Jeff Brown on November 28, 2003 at 23:02:13:

In Reply to: Re: Chock and runner alignment posted by Jeff Brown on November 28, 2003 at 22:48:36:

Same deal to find the brass insert nuts.

I could not paste the link.

Enter search at Thorlabs website:

http://www.thorlabs.com/index.cfm

"adjuster nut"

enter exactly as above.

Jeff Brown

PS: Sorry about the multiple posts

383

Posted by: Paul Goodwin on December 12, 2003 at 12:57:48:

In Reply to: Re: Chock and runner alignment posted by Geoff S. on November 26, 2003 at 18:49:07:

I've just about completed a prototype laser guide based on
Geoff's drawing. It looks really promising at this point.

I've played around with some different mirrors, and I'm happy to
report I see no reason to use first surface mirrors. The double
reflection and/or double refraction problems that occur with
second surface mirrors does not rear it's ugly head with this
device since any smearing of the reflected laser dot is in the
vertical plane.

This has allowed me to use a second surface mirror that costs
$0.35, and I don't have to worry about damage to the reflective
surface.

Plate runner construction

331

Posted by: Dan Gidcumb on November 28, 1998 at 09:24:23:

In Reply to: Plate runner construction posted by Bob Rast on November 11, 1998 at 12:24:21:

I've not tried this on my plate runners, but if you are building these for snow, I would put my money with the downhill ski racers who maintain a "structured" texture bottom. That is, the tuning process leaves fine longitudinal marks down the length of the ski. For runners, I would try an #80 grit then apply wax appropriate for the snow temperature. I have found that #120 grit is too fine for skis. Rub the wax out so it smoothly coats but does not completely fill the texture.

336

Posted by: Mark Kiefer on November 30, 1998 at 20:51:10:

In Reply to: Plate runner construction posted by Bob Rast on November 11, 1998 at 12:24:21:

This much I do know. Last year, on hard squeaky snow Rob Evans used a set of 440 C minimum inserts that were highly polished. Now some folks think Rob is a pretty good sailor, but he finished DFL in about a dozen races, with a good blend of sailors. The first two boats in each race sailed skinny T's, the next 2 boats were well sailed with minimum inserts, then a mix of plates and min inserts. We traded boats (Rob and I) and Rob won the race in my boat, I was DFL in his.
Yes there is something not good about polished sides in snow.
Mark Kiefer

Runner body construction

313

Posted by: Len Burz on October 17, 1998 at 10:42:56:

In Reply to: Runner Body Construction posted by Dan Gidcumb on October 17, 1998 at 07:51:00:

I would recommend either quarter sawn hardwood laminated bodies,
or as I have, aircraft plywood laminations, using a high quality
epoxy and some cab-o-sil and milled fibers added to slightly thicken
the epoxy, adding to its gap filling abilities. I would precoat plies
with unthickened epoxy, to allow for wood absorption, then applying
thickened mixture with a very short napped (3/16) mohair or adhesive roller to each surface, laying on plastic film on as flat a surface
as possible, stacking laminations to yield a body just over 7/8", putting plastic film on top, laying a very flat piece of steel/aluminum on top, and lightly/evenly applying clamping pressure to the layup. The runners can be incorporated into the wood body as per article in 'Reprints #6'. Body can be shaped and faired as you like,
just be certain to stay within the specs. Use a caliper/micrometer
and be certain that you don't go under the required wood body component thickness. Add carbon fiber side stiffeners, bringing the
thickness up to 1.02" (1.03125" max contained in chock). The front
6" portion can be tapered down to 1/4", which will streamline the
runners, and lighten the nose up a little. It's also possible to bore
holes in the wood body and insert custom turned balsa wood dowels (glued in) to further lighten the body, and provide vibration damping
(a vibrating runner is like a brake). The essential idea to this
message, is a laminated wood body will be more stable than a slotted
piece of wood (I've seen some really bowed-longitudinal-runners) So
a little extra work with diligence will yield a better product, which
will either reduce disappointment, or increase enjoyment/elation.

Posted by: Len Burz on October 20, 1998 at 22:31:38:

316

In Reply to: Re: Runner Body Construction posted by Paul Goodwin on October 19, 1998 at 17:45:30:

Paul, adding balsa is similar to adding foam to c-fiber golf club
shafts for reducing vibration- I believe the lightweight cell
structure of balsa would be more absorptive of vibration than a denser
wood (and is still wood, satisfying the current spec's requirements)- wood is known to dampen vibration, such as a wooden boat, as compared to a frp boat. The real trick is to find the locations where
to put the balsa dowels. The other question is how many holes to drill
without weakening the body? Wouldn't it be a bummer to bust up some
runners on a leward rounding!?!! I would suggest positioning these
damping balsa dowels at the front and rear of the wood body, where the distance away from the chocks is greatest, and the structural requirement are less.
Input from anyone experienced with harmonics, acoustics, frequency
damping, ect... would be appreciated.

Len Burz USDN4908

317

Posted by: Jim Olsen on October 23, 1998 at 16:26:32:

In Reply to: Re: Runner Body Construction posted by Len Burz on October 20, 1998 at 22:31:38:

If dowelling with balsa is effective you may need to compensate by using a stronger matrix host wood. I have used hickory in runner bodies with good results: good warp resistance, and a good survival record (2 for 2 dropping a runner in a hole). Hickory fibres interlace that's what makes it so tough. It has 2 drawbacks: weight and it's harder to cut. If the extra weight bothers you, laminating it with another wood should lessen that objection.

Pivot Point

813

Posted by: Luke Buxton on October 23, 2003 at 19:23:50:

Where do you place the pivot point on a 30" insert steering runner?

814

Posted by: Bob Rast DN1313 on October 24, 2003 at 07:32:25:

In Reply to: Pivot point posted by Luke Buxton on October 23, 2003 at 19:23:50:

I have put the pivot point on my steering runner the same as side runners. 1 inch aft of center. I’m sure you will get other opinions. I didn’t like the old pivot on Sarns steering runners thinking it was too far back and caused the runner to whip to one side or the other and possible loss of tiller. I also like to keep my inserts the same as they can be used for side or steering. For a brake you can take a standard Sarns brake and put a inch bushing in top hole with a bolt and wing nut or fast pin and just slide it on the runner using it for any insert.

814

Posted by: Paul Goodwin on October 24, 2003 at 09:20:18:

In Reply to: Re: Pivot point posted by Bob Rast DN1313 on October 24, 2003 at 07:32:25:

Like Bob Rast, I also put the pivot point on my steering runner
in the same location as the side runners. There is no reason
why you can't have more than one hole in a runner if you want
to try different locations for the front and sides and still
be interchangeable (up to 4 holes according to the specs - E.11)

However I don't put the hole in the same spot as Bob, I favor
a position a little further back. I try to find the section of
the blade that is relatively flat (between the "lead-in" at the
front and the "exhaust" at the back). I put the hole 1" - 2"
behind the center of this flat section. This comes out around
15-1/2" - 16" from the back for my 36" inserts. Don't ask me
to explain the science behind this location; it just seems to
work ok.

I always thought it would be a cool idea to add two more pivot
holes, one an inch forward and the other an inch aft. Then I
could try different locations and finally settle the location
question (at least in my own mind). However my deep seated
tendency to avoid choices when setting up my boat makes me
stick with the current location.

I also thought it would be cool to run around at a regatta with
a tape measure and a little notebook and write down where my
competition puts their pivot holes. I doubt if I would learn
anything very meaningful, but it would be a good psych-out :)

Glossary:
"Lead-in": the curved part of the runner at the front , back
to the point where there is a transition to the sharpened
"ice-contact" edge.

"Exhaust": the part of the runner at the back, from the end
of the sharpened "ice-contact" edge, with increasing curvature.

Check out the article by Henry Bossett ("Terms Involved in
Understanding Runner Design") on the IDNIYRA website for a
nice description of these and other runner design terms. You'll
find that Henry and I differ a little in our definition lead-in
and exhaust, but I think the final result will be about the same.

Angle Runners

617

Posted by: Wayne Matheson on February 05, 2002 at 12:53:18:

I'm going to build a set of angle runners and would like to know what is the usual method of shaping the angle iron at the front. Does the front curve upward? Are the webs bent around and welded? I have never seen any angle runners to go by, or pictures either. Please post any replies on the B.B for my e-mail isn't working

621

Posted by: Bob rast DN1313 on February 06, 2002 at 11:56:40:

In Reply to: slushies posted by Wayne Matheson on February 05, 2002 at 12:53:18:

I have built 2 pairs of angle slush runners and bent the curve in the front the old fashioned way, Brute force. You could go to a machine shop and have them bend the angle. The first set was soft steel from Menards [hardware superstore] about 4 bucks apiece. Don’t laugh got me to 7 in the silver fleet NA several years ago. I bent these by sticking under the work bench and prying up to form the curved front worked ok no kinks. The second set is 304 stainless angles. I made a jig much like a pipe bender used to bend conduit. I took a 2x6 x3 feet and cut a radius for the front profile and put a 45 degree edge to fit the inside of the angle. At the top of the front of the jig I put on a piece of steel strap to hold the end of the angle. Placing the angle on the floor slide the jig over the front end which puts the jig approximately 90 degrees to the floor push down on jig until the desired curve is bent. Make angles a little long so you can trim front and overall length. The steel angles I fastened with small counter sunk screws up near the runner body. A better method is having some threaded rod welded to inside of the angle to insert into body with epoxy. If you would like a sketch of the jig send a email.

623

Posted by: bob rast Dn1313 on February 07, 2002 at 10:29:17:

In Reply to: Re: slushies posted by Doug Gaudet on February 07, 2002 at 08:00:11:

here is a link to some pics of the jig
http://aolsvc.pictures.aol.com/NASApp/ygp/Start?event=NetLogin&shareInfo=87693cDddTnGOE9WFadK8hTL7ECqw7Rj4cZZIQbX3Lx2Z9E0d%2b4qpyE%2bzps9oSBRdBSXXdgCQzNR%0ai1zyEsIDXw%3d%3d

857

Posted by: Geoff Sobering on February 26, 2004 at 13:44:22:

I sorely missed having my slush runners at the NAs. I didn't bring them because they were in pretty tough shape when I bought them, and I haven't had a chance to clean them up. I'm going to rectify that right now, but I have really no idea what kind of crown, edge, etc. I should put on them. I'm assuming the metal surfaces should be polished very well to slide easily in the snow/slush, and that a hyper-sharp edge isn't needed, but beyond that???

858

Posted by: John Dennis on February 27, 2004 at 12:15:59:

In Reply to: Slush Runner tuning tips? posted by Geoff Sobering on February 26, 2004 at 13:44:22:

The angles that I used are polished to 800 grit. I used sand paper on a small batten. Stones tend to be a too harsh on the soft stainless. They are sharpened to 104 degrees and have about 17 or 18 inches of .008. The lead in is very long so that they don't plow. The entry is very important in my opinion.

I think that 100 degrees is probably the best. My angles are built at 90 degrees and are only at 104 at the edge until about one half inch wide.

I built a new set at 100 degrees but they are not ready to race.

Feel free to e-mail.

Insert Runners

Insert Design

831

Posted by: Geoff Sobering on November 26, 2003 at 23:04:38:

I'm curious about the reasons for selecting steel for insert runners between the min. 2" and max 3" width.

Paul Goodwin's classic article specifies 2.5", but it seemed that 3" would be *much* stronger, and the weight not that much more.

Cheers,

Geoff S.
US-5156

832

Posted by: Paul Goodwin on November 27, 2003 at 22:06:02:

In Reply to: Insert runner steel: 2.5" or 3" wide? posted by Geoff Sobering on November 26, 2003 at 23:04:38:

Looks like it's time for an update to that article, I haven't actually read it in years and it needs a tune-up.

I would definitely recommend using 3" steel...

625

Posted by: Doug Gaudet on February 15, 2002 at 10:18:22:

I was contacted thru this BB by Jan Adsten from Sweden. Some may know him, as he was to the Worlds in the past.
Anyway, he read my/our discussion on crown shape and measurements for runners, particularly inserts and he sent me a diagram of an insert with all the measurements, spacing and lines. It is drawn in CAD or some other drafting software and is going to be my bible. It supports and details Paul Goodwin's attempts to clarify small minds - namely mine. Paul's second lengthy email to this board and an hour of my buddy slapping me on the side of the head and I finally understood "where I can stick that feeler gauge", to get .008".I have this diagram that Jan uses in his Swedish publication and it is really good. He developed the drawing, I believe he owns the company, it's in the corner title box. He also says he would be pleased if I wanted to give out this file to North Americans.
If the BB service has a way of loading this file for public consumption I'll forward it to the janitor. Otherwise email me at my work and I'll attach it and mail it back to you. It is really informative, and the only thing left to interpretation would be anyone's subjective variations.
If you're interested, I was going to say "like me" but no one would admit to being like me, EH! E-mail me at work and I will mail them to you. I can't do anything executable because I'm behind a corporate firewall which strips everything even remotely looking like an executable.

630

Posted by: Bob Rast DN1313 on February 18, 2002 at 13:43:19:

In Reply to: Insert runner diagram posted by Doug Gaudet on February 15, 2002 at 10:18:22:

try this link , if you have problems email and I can send a copy

http://aolsvc.pictures.aol.com/NASApp/ygp/Start?event=NetLogin&shareInfo=87693cDddTmXgUOqCflDwdsA2iw7DTLmDIHe59qzYD12Z9E0d%2b4qpyE%2bzps9oSBRdBSXXdgCQzNR%0ai1zyEsIDXw%3d%3d

[Also available through links at www.icesailing.org the European DN board]

Runner Construction

249

Posted by: Ken Smith on March 10, 2002 at 16:04:06:

In Reply to: Re: busted an insert runner... posted by Paul Goodwin on March 06, 2002 at 17:43:15:

This got too long, but if you want to follow my experience, read on.

My two cents worth. Basis: Construction of two sets of insert runners and lots of discussion with many. None have broken. I sail the boat hard, sometimes in crummy conditions and high winds. I have, over the years, broken just about everything else on the boat at least once. Never runners. Overall, buying completed runners are a lot easier, and more expensive. That is why I only built two sets.

Caveats: I am hanging on at the bottom of the gold fleet. Lots of gold guys are still beating me...

First set: My first set were made of butcher-blocked ash, saw-cut slot and hand lay-up of roving and unidirectional glass on top, plus carbon cloth. The steel is maximum thickness and the inserts were glued as described by Paul in the reprints article, with "wet sanded" epoxy and a layer of glass between the insert and the slot. The eight holes with threaded rod were in place and epoxy filled before the glass and carbon were added to the body. These runners were made almost twelve years ago. They are still reliable and trusted when it is howling outside! I started with 440C steel purchased from Frye Steel in CA. Construction consisted of rough shaping, drilling, grinding, heat treating straightening and assembling. The runner steel was not precision ground. The steel came back from the heat treater looking like rocking chair rockers. I felt sick. The metal work done on a one-off basis in local shops was both expensive and time consuming. Times 5.

Critique: The hand lay-up results in a rougher outside finish. Little was ever done to taper the wood in front or to sand or trim the wood in the back. The steel is not quite straight, though the edges are very straight, making the edge appear to wander left and right on one runner relative to the steel. It is the edge that counts. The kindest complement I ever got on their appearance is non existent.

Lessons learned: 1. Get someone with experience to do the steel. 2. Lay up the glass in a form to get the surface appearance up to acceptable. 3. Precision grinding and straightening does a lot for appearance and is absolutely necessary to get to minimums.

Second set: A jig was made available to use in making the second set. I wanted minimum (3/16) 440C inserts, and Ron Sherry was selling the nearly-finished steel. He did the rough cutting (water cut from sheet, n/c controlled, including the holes), precision grinding for thickness, heat treating and straightening. The steel was delivered with an edge, straight, and within 0.002 inches of the right thickness. Hardness was Rc 55, right in the middle of the range for 440C to get hardness and toughness. Perfect.

Wood bodies were two halves of Finnish birch plywood, each half 7/16 thick by the right length and width. Shaping comes later. I routed away ½ the insert thickness and drilled the wood bodies to match the holes in the steel, eight places. Gluing and lay-up was a two-hour operation including cleaning the mold. Carbon cloth, carbon uni-fiber the length, the first wood body, threaded bar stock and epoxy into the holes, the second wood body, uni and cloth. The insert steel is wet sanded with epoxy filled with colloidal silica. No glass between steel and wood.

The mold is in two halves with supports for the steel inserts so the bottom of the runner ends up at one inch. One inch spacers are located above the runner and 1 inch spacers to ensure the top of the runner is also one inch. Of course, the mold's sides are very stiff, and the mold is on its side for the work. After closing the mold, clamp, clamp clamp. Later, after the runners come out of the mold, the final shape is scribed on the runner and the bodies are trimmed on a band saw. Sanding and a sealing coat finishes the job. I did the wood the weekend before the NAs, had help with the first runner into the mold Monday night. Tuesday night, one came out, the second went in. Wednesday morning, the second came out. At lunch time, the runners were trimmed to shape. Wednesday evening, the edges were sanded and the chock holes drilled, the edges were ground to final shape and a coat of sealer put on the wood. I left for the NAs Thursday, picking up Christain Seegars (G551) at the airport that afternoon.

Critique: Excess glue moved some of the carbon on one runner. The runners handled high winds and sticky ice at the Worlds with no problem. The bodies may be a little too flexible so carbon stiffeners will be added this summer. Appearance is good!
Lessons learned: Buying the insert steel was right! The mold process worked great! More care needed on the glue amounts and mold closing to prevent the cloth from migrating.

Darek Kardas's mold in Poland includes taper and shape. More time is spent on his runners preparing the wood prior to inserting into the mold. Carbon wraps all around the wood, including the top, and the finish appearance is excellent! Ron Sherry's runners are also excellent when bought fully finished. So are Jeff Kent's. Others including Ake Luks in Sweeden, Clapp in New Jersey (reportedly) are also making completed inserts. My labor is cheaper than theirs, however.

Insert Bodies – Wood

671

Posted by: Geoff Sobering on April 04, 2002 at 22:11:36:

I'm in the process of building a couple of new insert and angle runners this off-season. From reading the notes here, it seems the most popular material for the wood body is Birch plywood.

What's the best way to get/make the necessary 7/8" thick material for the wood part of the body?

I've seen some very-rare mentions of 7/8" plywood sheet for sale on the Internet, but more common is the 3/4" (and the metric equivalent). I just finished laminating a pair of bodies from 6 mm Baltic Birch plywood (three full-thickness sheets, and one planned down to 0.150"). It worked well, but it was also alot of work. I'm thinking of laminating a 3mm sheet to a 3/4" for the next pair of bodies. For what it's worth, I also have a pair of Hard-Rock Maple butcher-blocked blanks waiting for some *really* nice pieces of steel.

Any other suggestions (or sources)?

Cheers,

Geoff Sobering
US 5156

[Several posts using Kevlar as reinforcing cloth omitted.]

678

Posted by: Jane on April 07, 2002 at 14:24:12:

In Reply to: Re: Plywood runner-bodies - 2X 3/8" +KEVLAR posted by Geoff Sobering on April 06, 2002 at 09:35:26:

Plese take note of the Interpretations of the Offcial Specifications
11/23/87: Material - Kevlar cloth may not be used in DN construction.

The difficulties Will Winter has been having with the material demonstrate one of the reasons it is not an allowed material. In addition, the characteristics of kevlar do not appear to be superior for DN use that are the characteristics of the materials that are allowed. Therefore, there is no need to allow kevlar.

672

Posted by: John Davenport on April 05, 2002 at 11:42:57:

In Reply to: Plywood runner-bodies - material? posted by Geoff Sobering on April 04, 2002 at 22:11:36:

Geoff,
I have made a number of runners using “Baltic Birch” plywood. It has good isotropic properties in the length and vertical directions. You are right about the thickness problem, but that is the case with any runner body project (nothing worth using comes 7/8” standard). To get my bodies the correct thickness AND matched-pair thickness, I use a “Timesaver”. This is a wide belt sander that works like a planer. They are about $5000.00, but I take a woodshop class through a local Tech College for $108.00/term and they have one in the shop. It is the perfect machine because you can reduce thickness slowly and accurately. A planer is OK, but it is easy to overshoot and go below 7/8”. I use it for plank plies too, because it the surface finish is sanded not planed. This eliminates chip-out of the grain where cracks can propagate from and reduces finish time. I hate sanding!

John Davenport US4961

679

Posted by: Paul Goodwin on April 08, 2002 at 08:05:19:

In Reply to: Re: Plywood runner-bodies - 2X 3/8" +KEVLAR posted by Geoff Sobering on April 06, 2002 at 09:35:26:

Geoff pretty much hit the mark with his comments. As Jane has
pointed out, Kevlar is not allowed ANYWHERE in DN construction.
There has been a lot of "discussion" of the pros and cons of
Kevlar, but none of the pros are beneficial enough to change
the current rules.

Geoff is also right about the 7/8" minimum thickness of wood
(before adding any reinforcement). One easy way to get there
with plywood is to use two layers of 3/8" plywood with a layer
of 1/8" plywood in the middle. Hobbie stores sell 1/8" aircraft
birch plywood, although frequently only in small pieces. There
is no problem with using several smallish pieces of 1/8" plywood
and just butting them together to make up the length of the
body -- as long as they are confined to the center of the body
(sandwiched between the two 3/8" pieces). Stresses are almost
nonexistent on the centerline of the body, so the butt joints
will be fine.

Now back to one of my favorite rants -- why use plywood for
runner bodies???? Ron Sherry and I have had great success
with solid White Ash or Hard Rock Maple bodies over the years.
We started with Ash, and now use Hard Maple exclusively.
Maple is easy to find in most areas of the country and is
usually inexpensive. Good plywood (such as aircraft birch,
Baltic Birch, Apple Ply, etc) costs more than solid Maple,
and plywood reduces the stiffness of the body. John Davenport
hit the nail on the head when he mentioned that plywood "has
good isotropic properties in the length and vertical directions".
But with a runner body I want more stiffness in the long the
direction than in the height. Why anyone would want to
sacrifice any stiffness baffles me, especially if in the end
a King's Ransom is paid for carbon fiber to stiffen them up.

The only real drawback to solid wood bodies is getting them
to the proper thickness. Most lumberyards have a thickness
planer, as do all millworks. The trick is the convince the
operator to take the time to plane the raw stock to exactly
7/8". An even better bet is to have the stock sanded to
thickness (also available at most millworks) since belt or
drum sanders usually have much better control over the
thickness than planers. I have my own planer, and can
consistently plane stock to within .005" of the desired
thickness, but it takes a different approach than most pros
would use.. One additional tip, cut the stock to 36" lengths
before planing or thickness sanding. It is much easier to
keep the bodies perfectly flat with the shorter length.

One caveat, a solid wood body can split along the grain.
This is where the "isotropic" properties of plywood pay off.
When using solid wood, make sure some of the reinforcement
(glass or carbon fiber) is oriented vertically. This keeps
the wood from splitting along the grain.

689

Posted by: Jim Olsen, on June 14, 2002 at 14:22:32:

In Reply to: Re: Plywood runner-bodies - 2X 3/8" +KEVLAR posted by Paul Goodwin on April 08, 2002 at 08:05:19:

One way to keep solid wood bodies from splitting along the grain is wood selection. The first inserts I built were of ash. It didn't take long for them to split. Then I switched to hickory, which solved the splitting problem. Hickory has interlocking fibers, so it's not prone to split. It has good shock resistance too. That's probably why it's the wood of choice for axe handles. Hickory's third feature is that you have to really work at it to warp the stuff.

If you are really concerned about keeping weight down on your runners just add hickory layers in the zone most likely to split, about where the top of the cut for the insert would be.

682

Posted by: Steve Orlebeke on April 08, 2002 at 11:51:09:

In Reply to: Re: Plywood runner-bodies - 2X 3/8" +KEVLAR posted by Paul Goodwin on April 08, 2002 at 08:05:19:

Paul asks "why use plywood for runner bodies ?". One reason Paul referred to is that it is stronger in the 90 degree direction(0 degrees being in the fore / aft direction). Plywood prevents blade breakout such as Will from White Bear Lake has experienced. I would rather put all of my stiffening carbon into unidirectional fibers in the fore and aft direction rather than wasting any at 90 degrees. I also like the fact that the birch plywood is lightweight and the strength properties are very consistent from sheet to sheet. No two wood boards have the same grain structure. Is this really a problem, I don't know. Which runners are stiffer ? I don't know that either. I think both construction methods are good and produce similar results.

Orly

Insert Bodies -- Reinforcement

248

Posted by: Paul Goodwin on March 06, 2002 at 17:43:15:

In Reply to: busted an insert runner... posted by WWBL on March 06, 2002 at 12:25:03:

When I was mentioning laminated bodies, I was referring
specifically to bodies with all of the grain oriented the
same way. I have seen many runners made of wood laminated
cross grain, like plywood (or in many cases, commercially
available plywood).

While the vertical plies add cross grain strength (and
would have helped with the type of failure you experienced),
they reduce the stiffness in the direction where it is
most critical. Runners made with plywood bodies are not
as stiff as solid wood, this can be easily measured.

While I'm not familiar with the layup of carbon fiber
used by Dave, Keith, and Tom, I would not divide the role
of the different layers quite the way you have. Here is
my take on the layup:

1) Use only unidirectional plies. Woven fiber has much
less stiffness, and also the layup will have a lower fiber
density than with uni (ratio of fiber to resin). Speaking
of fiber density, the best way to lay up the carbon is by
vacuum bagging a whole sheet on a flat surface, then cut
the sheet into strips and glue them on the body. This is
the way get the highest fiber density.

2) You'll need fibers in two directions, one oriented
vertically, and one oriented horizontally. The vertical
layer handles the side load from the blade and keeps the
wood from splitting along the grain. The horizontal
layer adds stiffness to the runner.

Here is one observation - you can't have too much stiffness.
By stiffness I'm referring to the longitudinal stiffness,
like when a side load is applied to the front of the runner.
If the runner is not stiff enough, then it will deflect
when there is loading in front of or behind the chock.
The first thing that is noticeable is a runner that
chatters during a leeward mark rounding, really stiff
runners don't chatter at all.

There is no point in adding any more vertical plies than
is necessary to keep the runner from breaking. So this
gets down to the how much of the layup is vertical and how
much should be horizontal. I'd like to tell you, but I
don't know (I buy mine from Ron, it's just so much easier).
I would say 50% each way would be a good starting point,
but I would put more horizontally myself and risk breaking
another body. That's the only sure way to find the limit,
by testing to failure.

I would take off the stiffeners in deep snow, especially
when it's hard packed.

872

Posted by: Geoff S. on March 31, 2004 at 16:16:56:

In Reply to: Re: Carbon runner stiffener layup? posted by Paul Goodwin on March 31, 2004 at 13:32:52:

Paul,

As usual, many thanks!

I'd thought briefly about doing a pure uni layup like the one you suggested, but discarded it and concentrated on cloth - I don't remember why...

> I'm also a little confused by your math "We have 4+2=6
> lengthwise layers ...

Yeah, I cut some corners in that caluclation and just counted layers, treating the fabric as two layers, one at 0 and one at 180.

If I'm reading you correctly, you prefer to layup the sheets by themselves, and then bond them to the bodies later?

I was planning to do the entire process in on step between two flat sheets of glass/steel with precision 1" spacers. Making the sheets alone and bonding them to the bodies later would certainly simplify the assembly process. It would also allow us to use more easily vacum-bag the assembly (I couldn't figure out how to make the two-sheet-and-spacers system work with a vacum). Luckly we have all the gear for bagging; simple sheets will be a ton easier than the last project: half-mast sections (I don't want to talk about it...).

Another advantage is that we could experiment with adding molded-in stiffeners, by inserting a foam or wood strip covered with extra layers of Carbon on top of the main layup.

Cheers,

Geoff S.

870

Posted by: Geoff Sobering - US-5156 on March 31, 2004 at 12:58:14:

In Reply to: Re: Carbon runner stiffener layup? posted by charlie on March 31, 2004 at 12:19:10:

> Check this site for carbon fiber descriptions. www.carb.com Their
> prices are pretty goo also.

Great site! Lots of product data (esp. the ever-important "thickness dry/laminated"). I haven't looked at the prices carefully, but they look very good, too.

Thanks!

Cheers,

Geoff S.

BTW, here are the composite supplier's web-sites I know of:
...http://www.fibreglast.com
...http://aircraftspruce.com
...http://www.wicksaircraft.com
...http://uscomposites.com
...http://www.carb.com/

Posted by: Geoff Sobering on March 30, 2004 at 17:45:33:

I'm getting ready to order the Carbon fiber to make some insert runners over the summer. From reading and talking with people I've come to the conclusion that the stiffener sheet on each side of the runner should be:
...1) 1/16" thick
...2) At least 1000 g/m^2 (=29.5 oz/sq yd) of Carbon
...3) About 80% fibers oriented along the runner body.

What I'm looking for is:
...1) Confirmation of the parameters above
......(or suggestion of better ones)
...2) Specific layup(s) that people have had good
......luck with.

I'm not confident about my conversion of the dimensions listed in the various catalogs into an adequate layup.

Cheers,

Geoff S.
US-5156

----------------------------------------------------------

FWIW, here's my calculation of a layup from what looked like the most suitable materials I could find from various suppliers:
...1) 5.7 oz/sq yd fabric (usually a "twill" weave)
...2) 4.7 oz/sq yd unidirectional

The first problem that I ran into is estimating the thickness of the final layup. For example, the 4.7 oz unidirectional material is generally listed as being 0.007" thick. However, Aircraft Spruce lists their 4.7 oz uni as being 0.012" thick when laminated. The 0.007" value seems too small, but the 0.012" seems a bit thick (although it is about 50:50 fiber:resin ratio).

If we assume the thickness of the 5.7 oz. material is roughly similar to the 4.7 oz, then we can calculate the number of 0.012" thick layers of Carbon that would fit in the 1/16" (0.0625") we have to work with:
...0.0625"/0.012" = 5.2

Rounding up to 6 layers (because we think 0.012" is an over-estimate), and allocating 4 uni and 2 fabric, we can calculate the total weight of Carbon in the stiffener:
...(4*4.7) + (2*5.7) = 30.2 oz/sq yd

This is just about the recommended 29.5 oz/sq yd, so that seems reasonable.

We have 4+2=6 lengthwise layers, and 2 crosswise layers, so the ratio of lengthwise to crosswise fibers is also close:
...6/8 = 75%

So, my first guess at a layup would be:
...1) 1 layer of 5.7 oz cloth
...2) 4 layers of 4.7 uni
...3) 1 layer of 5.7 oz cloth.

If this layup (or one like it) is reasonable, then the good news is that it looks like the cost per runner for Carbon is about $46 (before any volume discounts). I was surprised(!); that number is amazingly close to the $20-$25 per runner I estimated that simple Aluminum angle stiffeners would cost. For some reason I seem to remember the costs for Carbon were *much* higher when I looked at materials costs about a year ago.

For fun:
http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=1000+g%2Fm%5E2+in+oz%2Fyd%5E2%3D

Posted by: Paul Goodwin on March 31, 2004 at 13:32:52:

In Reply to: Carbon runner stiffener layup? posted by Geoff Sobering on March 30, 2004 at 17:45:33:

I have used quite a bit of the uni carbon from Aircraft Spruce,
and I think their material is very high quality. Don't use woven
cloth for the bulk of the layup since it generally yields a low
modulus (stiffness) and poor fiber/resin ratio.

You should plan on using a vacuum pump, along with "peel-ply" and
an breather/bleeder (polyester quilt batting works well as a cheap
bleeder). This is the only way to get a good consistnent layup
with a high resin/weight ratio (60-80%). Practice on some
fiberglass to get comfortable with the process. Wet layup by
hand (not using a vacuum bag) usually yields fiber/resin ratios
around 50%.

I would recommend a layup using the 0.033 lb/ft^2 uni carbon
from Aircraft Spruce (or an equivalent) (http://www.aircraftspruce.com/catalog/cmpages/graphtapes.php) in
the following schedule: 0/90/0/90/0

This should give you a finished part with 0.050"-0.060" thickness.
If you do a good job of the layup and get close to 0.050", you
can add another layer to get the thickness up to 1/16" (0.063").
This last layer can be 0deg uni or 3k plain weave carbon.
It would be a good idea to make the initial layup a little
bigger than required, so you can use a piece of it as a sample
to see if you can add a layer and stay at or below 0.063".

Since I'm only talking about adding a small amount of plain
weave, it doesn't make sense to buy it just for this application.
Let me know if you go this route and I may have a small piece
of plain weave laying around that I would part with...

I'm also a little confused by your math "We have 4+2=6
lengthwise layers, and 2 crosswise layers, so the ratio of
lengthwise to crosswise fibers is also close: ...6/8 = 75%".
You listed 4 layers of uni (I assume all lengthwise) and
2 layers of cloth. Here is how I would calculate the ratio
of your layup:
(4.75*4 + (5.7/2)*2) / (4.75*4 + 5.7*2) = 81%
However, I don't think you can get that much cloth into
a 0.063" section since the 3k woven cloth is definitely
thicker than the uni.

With my proposed layup I calculate the following ratio:
4.75*3 / 4.75*5 = 60%
or if you sneak in a layer of 3k plain weave:
(4.75*3 + 5.7/2) / (4.75*5 + 5.7) = 58%
If you added a layer of 0deg uni, you'd get:
(4.75*4) / (4.75*6) = 67%

These fiber direction ratios are well below you're 80% target,
but I think it provides the right balance of longitudinal
stiffness to cross grain strength if you use solid wood bodies
like I use...

Posted by: Geoff Sobering - US-5156 on April 02, 2004 at 17:01:36:

In Reply to: Re: Carbon runner stiffener layup? posted by Paul Goodwin on March 31, 2004 at 13:32:52:

This looks almost too good to be true, so I thought I'd see if anyone else could find a problem with it...

Carb.com is selling an 8.9 oz/sq yd unidirectional Carbon material that looks almost ideal for runner body stiffeners. The material is 24" wide and sells for $15.23/yd + shipping & handling (more on costs below):
http://www.carb.com/catalog/fabric/uni-carbon100/pages/1289U-24TQ.html

At 8.9 oz/sq yd, 4 layers would make a stiffener of 35.6 oz/sq yd (3 layers would give 26.7 oz/sq yd). Four layers might be a bit thick, but might work if one is careful with the layup (good vacuum bagging). I would probably do a 0-0-0-90 layup (outside-inside) for a 75% lengthwise:crossways ratio.

At 24" wide, one can get six 4"x36" strips per running yard of material. Since each runner uses eight strips (four per side), you use 1.25 yards of material per runner for a base cost of:
1.25 yd/runner * $15.23/yd = $19.00/runner

Considering that Aluminum angle for stiffeners (2"x2"x0.25") seems to cost just about $20/runner ($3.33/foot), the Carbon seems like an amazing deal.

To be totally fair, I called Carb.com and got a complete estimate of shipping and handling for enough material for 9 runners (12 yards):

material: $182.76 (= 12 yd * $15.23/yd)
cutting: $15.00
shipping: $18.00
-----------------
Total: $215.76

Total cost per runner: 215.76/9 = $23.97

If I can't find any problems with this plan, I'll probably order some, dust off the vacuum pump, and make a test sheet sometime in the next few weeks.

Cheers,

Geoff S.

886

Posted by: Geoff Sobering on July 14, 2004 at 15:21:13:

In Reply to: Re: Cheaper than Aluminum?!? posted by Geoff Sobering - US-5156 on April 03, 2004 at 10:23:19:

Last night we bagged-up our first Carbon insert-runner stiffener sheet. It came out very nicely. Price for materials is just about $15/sheet (Carbon, glue, and misc. consumables).

The materials are:
2 x 300g/8.9oz 12k unidirectional (part #: 1289HMU-24TQ)
1 x 657g/19.5oz 12k x 12k twill-weave fabric (part #: 121952-50TQ)
Plain-old WEST epoxy

The layup is: uni/fabric/uni

This gives a total of 1257g/27.9oz of Carbon with about a 75:25 lengthwise:crosswise ratio. The thickness of the sheet is about 0.05" (1.3mm); we were afraid it might end up too thick with the three heavyweight layers of Carbon, but those fears appear to be unfounded.

There are a couple of "lumps" in the peel-ply side where we didn't get even pressure (not enough batting between the peel-ply and the bag - just careless...), but they are solid and no more than 0.06" thick (1.5mm), so they shouldn't make the complete body too thick.

We're planning to laminate a second sheet soon and assemble a "test" runner (using some non-stainless steel I have lying around) soon.

Cheers,

Geoff S.
US-5156

Carb.com

Fixing broken inserts

246

Posted by: Paul Goodwin on March 06, 2002 at 08:33:50:

In Reply to: I had TOO MUCH FUN: busted an insert runner... posted by Will on White Bear Lake on March 05, 2002 at 23:50:05:

He Will,

Sounds like something I would do! I remember breaking both inserts at a weather mark rounding on rough ice and high winds, and still managed to sail to the leeward mark on just the bodies. I don't think anyone ran over the blades I left behind at the weather mark, or at least I didn't hear about it. Ahhh, those were the days...

You can repair just the broken runner, but it sounds like the body was too weak, so it would be a good idea to build new bodies for both runners. The hardest part of the whole process is usually getting the blades out of the old bodies if they are held together with screws or threaded rod (mine weren't in the previously mentioned incident). It's frequently a job for a big hammer and a cheap chisel. Don't forget the cussing and swearing, and a shot of your favorite liquid refreshment may not hurt either.

I don't know of anyone selling "blanks", but the wood body is very easy to make. My wood of preference these days is hard maple. If you can find nice clear straight pieces 36" x 5" x 1", then you're home free. Otherwise you may need to build the body up from multiple strips to get the 5" height (picture it like a "butcher block" of laminated strips). I'm sure you will find people saying that this lamination is necessary so the bodies don't warp, and you may want to do the extra work if you're in that camp.

The body needs to be planed down to 7/8" thick - the minimum allowed by the specs. If you don't have access to a planer, you should be able to find a shop to do it for you (you can even try the local high-school wood shop).

For the assembly technique, I would recommend reading my article on building insert runners on the IDNIYRA website. I still make my own runners this way, and it truly isn't rocket science! I don't think a jig to hold the runner straight is required as long as the steel blade is straight. If the steel is really crooked then a jig won't fix it anyway...

One thing you may want to consider is getting a set of premade carbon fiber pieces to go on the outside of the wood body. These are 1/16" thick, and you just glue them onto the bodies. This adds the necessary strength to keep the body from splitting along the grain (like yours did), and adds quite a bit of stiffness at the same time. This combination has worked pretty well on my 3/16" inserts without any additional stiffeners. You can get these premade carbon sheets from Ron Sherry or Jeff Kent. You can also make them yourself if you have access to vacuum bagging equipment, although it's a bit tricky to get right the first time.

Good luck, and remember - this sport is supposed to be fun! Putting together nice runners is one of the more satisfying parts of DN building in my opinion. This whole process takes only a few nights once you've had some experience with it, so you could be back in action by the weekend.

Runner steel

2267

Posted by: brian on August 03, 2004 at 02:29:11:

In Reply to: runner material ? posted by Jay McIntyre on September 28, 2003 at 17:37:26:

I’ve been wanting to experiment with different mat'ls. 1018 cold roll is really cheap, and comes pretty flat. 303 stainless is my first choice as you can file it easily, and it will hold a much better edge than 1018
or other cold/hot rolls but is more expensive. tool steels would be perfect, but they have to be annealed, machined, re-hardened, then sharpened. Can’t see any cheap way to use tool steel. i would stick to cold roll or stainless for practicality. If you have a way to sharpen it 440 stainless (any knife blade) would be great.

2127

Posted by: Bob Dill on October 19, 2003 at 17:06:33:

In Reply to: runner material ? posted by Jay McIntyre on September 28, 2003 at 17:37:26:

Jay,

Sarns used to use 1050 and have the edges induction hardened enough that they held up well but still could be filed (Rc 40??).
Many insert runner makers have been using 440C and having them completely hardened to Rc55 or so. This is an expensive proposition.
Some Skeeter sailors used to use 1095 with no hardening.
Lots of have used cold rolled 1020. It is cheap, easy to find, straight and easy to work with. It does not hold an edge forever and it tends to gall more easily when stoning the runners but it is great for inexpensive runners or experiments.
Tool steel (A2 or A6, D2, etc) all would make great runners. It is easily available but relatively expensive. If you go this route, talk to your heat treater for specific suggestions on which alloy he can keep straightest and what he recomends for a final hardness. Too hard can chip and be a bear to sharpen (eg D2 at full hardness. I am sure others can come up with several more options.

Bob

Building Runners

500

Posted by: Ken Smith on August 27, 2000 at 22:23:12:

In Reply to: Shaping runners posted by Ed Atkeson on August 24, 2000 at 15:47:48:

Ed:

Go to the main page, in the Information section, the archive articles and read ALL the articles on runners.

I learned the following in making my own 440C inserts:
1. Shape before heat treating.
2. Rough grind before heat treating.
3. Blanchard grinding is often done, but is not necessary. It ensures the plate sides are flat and below maximum.
4. Heat treating may warp your nearly complete blades.
5. Warped blades can be straightened with heat, by an artist.
6. Heat treating 440 is necessary.
7. Induction heating and quenching the edges only is likely a good thing, and probably won't warp runners as much.
8. Minimize the radius in the lead in.
9. The exhaust should rise slightly and be dull. You don't want the tail of the runner to chip ice when the nose hits a little bump.

Good Luck!

Ken Smith
DN4137

Hardness

789

Posted by: Bill Condon on February 27, 2003 at 15:16:43:

In Reply to: Runner metalurgy posted by George on February 27, 2003 at 13:07:08:

The predominate metal of choice here in the US seems to be 440C stainless(not Carbon steel)and hardened to as high a rockwell as possible.(to hold an edge.)Europe and the swedes in particular are running stellite runners which seem to hold an edge quite well. Haven't really seen many US sailors with the stellite runners here. Sarns (I believe) still makes an insert blade of carbon steel and flame hardens the edge, some of the other suppliers also sell 440c inserts that are avaiable.

790

Posted by: Ken Smith on March 02, 2003 at 23:31:18:

In Reply to: Re: Runner metalurgy posted by Bill Condon on February 27, 2003 at 15:16:43:

Bill is partially right. Not too many people in the US are using stellite edges. But a few are. Stellite is a material developed for its lubricity and toughness. Several variations of the material are around in industrial use. The type in use on runners seems to me to be applied with a gas welding technique, "buttering" on the material to an edge and then grinding. I have looked at some runners and the weld pass puddles are pretty obvious in a microscope or with a good magnifying glass, especially near the ends.

440C is a teat-treatable martinsitic "stainless" steel. If not tempered as part of the treatment, it can become very brittle, so the most common, and best hardness, is in the mid range of possibilities. I believe that is Rockwell C 65, but I am not near my books right now. I bought a set of steel from Ron Sherry, shaped, hardened and ready to mount, and checked the hardness. He had it RIGHT ON in hardness. If you are doing your own 440C runners do NOT go to the fully hardened state. The runners will crack through.

As to the best runner, that is a subject of much debate and mythology. This weekend I sailed on soft carbon steel plates with a hard oxide "gun blue" finish on the sides. Others used 440C, soft stainless (304), sarns plates (hardened carbon steel) in a varieto of cuts, shapes and profiles. Several were fast in softer ice, 40 % cover of sticky 1 inich snow (later in the day, slushy) combined with fluky winds. But there was no obvious best choice of the 18 boats on Lake Geneva. In this case, shorter runners were faster because maneuvering to miss the snow paid off big, and short runners with more crown do not loose as much speed as long runners when turning. When the wind came up a little, the longer runners made up in top end more than they lost in turning.

Hard runners hold their edges longrer than soft runers. Soft runners seem faster, ususlly in softer ice ( Snow ice with lots of air in it, spring ice going soft, and black ice softening in warm weather.)

Prioritizing your selection: A great set of runners is 3/16 inch thick, 36 inch long 440 C (or stellite)inserts. They work in 90% of all conditions we sail. A short set of soft steel or 304 plates for sticky snow is a good second set. A set of full length maximum width inserts for hard blowing, rough ice or high wind on softening ice is a good third set. In special conditions, other runners may be better. Angles in slush, min t's in refrozen thin snow cover, and in pebbly ice, the hot ticket is 100 degree grind 1/4 inch 440 C with dead flat the whole length except the ends.

I lately am keeping "pairs" and using a plate or a 30" insert for the steering runner.

But of most importance: Align, align align. Power up the rig enough to hike in the puffs, but not too much to be hiking all the time. Get quality tiller time. Sail against the best.

794

Posted by: Ken Smith on March 04, 2003 at 15:37:12:

In Reply to: Re: Runner metalurgy posted by Bill Condon on March 04, 2003 at 11:07:52:

This steel, 440C will treat to hardness of Rockwell C of 60 (HRC 60) or more, but in that state, it is brittle. To get the ductility back, a subsequent temper step at about 950 degres F is required. This actually softens the steel back to a target of HRC 52-54. This is still hard! but the runners are much more durable in that state.

In my earlier post, I mis-stated the HRC 65, and my runners ARE HRC 53. The heat treater will know how, as he is using books similar to what we have here at work. You want the 440C "heat treated, quenched and tempered to a final hardness of HRC 52-54"

If you want to get even fancier (and more expensive) there is a way to dimensionally stabalize the 440C by cold quenching to - 100 def F as part of the quenching step. Heat treaters are magicians, and they like to maintain their aura. If you ask, he may be impressed. But he will likely not give you back a straight answer.

One last comment: When the set of runners I did myself came back from the heat treater, they were shaped like rocking chair bases. UGH. The material WILL warp! Be prepared to either have it flame straightened, mechanically straightened or ground flat after the heat treat step.

After having done all this myself once, I will always buy the parts in a near finished condition forevermore. Ron Sherry is my source for runner steel.

Ken Smith
DN 4137

799

Posted by: P 81 on March 17, 2003 at 08:06:17:

In Reply to: 440C Heat treating. posted by Ken Smith on March 04, 2003 at 15:37:12:

I read your discussion. I have some 304 plates. You wrote that these blades are softer than 440 c. Is it possible to hardening this material? In my metallography book it is said about dispersion hardening. What HRC should has 304 blade ?

Thanks in advance.
Jarek Gorski
DN P 81

806

Posted by: Ken SSmith on April 21, 2003 at 20:48:19:

In Reply to: Re: 440C Heat treating. posted by P 81 on March 17, 2003 at 08:06:17:

There are a family of stainless steels which cannot be heat treated for hardness. These include 304 and 316. These materials are often used in hardware. 316 has slightly more Ni in its composition and is more resistant to chloride attack, and is best for salt water hardware.

Only cold work can harden this material, such as bead blasting or drilling with a dull bit. Heat will only anneal, softening work harden areas to the same hardness as the bulk material.

Sorry for the long delay in answering, I missed seeing the question.

Runner Crown and shape

569

Posted by: Bob Rast DN1313 on October 12, 2001 at 13:39:56:

Anyone have Idea how much rocker and flat should be used for 30 or 36" inserts. and plate runners.

574

Posted by: Roger Livingston on October 22, 2001 at 07:23:33:

In Reply to: Runner shaping, Optimum Rocker and Flat ? posted by Bob Rast DN1313 on October 12, 2001 at 13:39:56:

I'm not a racer, so my recommendations may not be the best answer. I sharpen my runners on a specially designed device using a grinder and sliding carridge. I center the flat under the bolt hole. On 30 inch runners I put a 3 1/2 inch flat and on 36 inch runners I put a 5 inch flat. For the rocker, I shim the blades up .020 inches. These measurements seem to work well from light to heavy air.

Since I will be sharpening many runners for other sailors this year, I hope to put together a chart of measurements based on runner type, length and use. I'll publish my results.

Roger Livingston
DN 4568

223

Posted by: Doug G on February 05, 2002 at 10:31:50:

I am presently constructing two new sets of runners - one are
"bullnosed" and the other are inserts. With my little bit
of knowledge(the dangerous bit) I made the lead in curve
radius quite short. It only travels about 2 and 1/4 inches
from the front. A lot of pictures on the 2002 championships
show a lot of lead in. What is the purpose, technical reason
for such a lead in? Longer skis go faster, so do skates - more
surface on the ground equals more speed.
The lead in in the pictures appears to be almost as big as
my first set of home builts. It looks like these runners
have at least 3 1/2" of run in curve that doesn't contact
the ground? This would be 10% (almost)of the total 30".
Also, I read where the "boys" say that the tail end
treatment is also important. It reduces run out drag,
maybe, if there is such a thing.
It's hard to believe that so much
run in is just for climbing rough surfaces????!!!!

224

Posted by: Paul Goodwin on February 06, 2002 at 08:24:44:

In Reply to: Runners-lead in/out radiis posted by Doug G on February 05, 2002 at 10:31:50:

Here is my impression of lead-in and lead-out on runners.
The ice we sail on is rarely smooth. The purpose of the
lead-in on most runners is to climb over the rough spots
with as little disturbance as possible (flying ice chips
is a bad sign). Every time a blunt runner hits a chunk
of ice there is an impact, and that impact takes away
energy. The harder the impact (and the more ice chips
you produce) the greater the energy loss. The reason you
need lead-out (or exhaust in some circles) is that when
the runner rides up over a bump, you don't want the
trailing edge to dig in. Like the "too blunt" nose,
digging in the trailing edge makes lots of ice chips,
and that takes energy.

A 3-1/2" radius is about the bluntest nose that I would
recommend. Actually I'm guessing here a little since
I don't have a runner handy to measure, but the Sarn's
bullnose is as blunt as I would go. Behind this 3-1/2"
radius, my runners have a gentle curve all the way to
the trailing edge (no flats). Where the leading and
trailing edges end, most of my runners are about 3/16"
to 1/4" off the ice. The lead-out starts around 3-4"
from the trailing edge.

The lead-in and lead-out are also rounded over to eliminate
the sharp edge. At both the very front and back edges, the
edge is totally rounded. Note that rounding over the edge
effectively increases the clearance (or rise) between the
edge and the ice. So make sure you allow for the rounding
when rough profiling the runners.

This is generally how my runners are set up, but there are
a few variations. My slush runners (angles) have quite a
bit more lead-in and lead-out, and I think this helps them
to ride up out of the slush. But then, I've seen some
European slush runners (on very competitive boats) that
were blunt in the nose like any other runner and very flat.
Go figure...

My snow plates have a flat leading edge at about a 45
degree angle, with only the bottom couple inches radiused.
Since we rarely encounter bumps higher than 2", this
seems to work just fine. This actually decreases the
edge length versus a full radius nose, but that's ok
on a snow plate where the edge is short on purpose.

227

Posted by: Paul Goodwin on February 07, 2002 at 14:32:17:

In Reply to: Re: Runners-lead in/out radiis posted by Doug G on February 06, 2002 at 09:47:27:

Here is a better (I hope) description of the "crown" in my
runners. Any dimensions I talk about here are referenced to
"standard" runners. For instance, runners like "slush"
(angles) or "snow plates" could have a significantly different
lead-in from insert runners .

First, it makes sense to talk about how I measure the crown.
This is the probably the same method as you described with
the 0.008" feeler gauge.

1) Place the runner on a VERY flat surface. A surface plate
is perfect if you have access to one. I use a steel I-beam
that I've had machined flat. Industrial machine suppliers
sell ground and hardened steel straightedges. If you go
this route make sure you get something of adequate thickness
(1/4" minimum) since you need to set the piece on edge for
it to be stiff enough to maintain it's flatness. I personally
have a hard time with holding the runner on a 1/4" wide
surface, but it works fine for Ron Sherry and many others.

2) Press down on the runner directly above the pivot bolt
to simulate the loading the runner sees in use.

3) Slide 0.008 shims (I use paper card stock for shims) in
from each end until they "stick". The idea is to find the
spot where the distance between the runner and the surface
plate is exactly 0.008".

4) Measure the distance between the shims. Since the runner
edge has a slight curve, the distance between the shims is
a measure of the curvature. The more crown (or curve) in
the runner, the closer the shims will be to each other.

Going beyond this measurement, you'll find people using
different thickness shims. This will provide a measure of
the curve in different spots along the runner. A great
idea I suppose, but it's not something I do.

You'll also find discussions about the amount of "true flat".
True flat is a section of the edge below the pivot bolt where
the crown is actually flat. A runner with "true flat" should
sit flat on the surface plate, with no light showning, and no
"hollows" (negative crown). Hollows are particularly bad
since when the runner tries to turn, it will scrub really
badly. I don't believe in true flat (nor does Ron Sherry -
who taught me all I know about iceboating), and I work
really hard to insure that when I rock my runner from the
front to the back (to change the contact point) there are
no hollows. In other words, the runner crown is a smooth
curve from the leading to trailing edges.

Here is a quick summary of the amount of crown (measured
with 0.008" shims) in my various runners:
Snow plates (26" long plates): 9-10"
Sarns bullnose (36" long plates): 15-16"
1/4" inserts (36" long): 18-20"
3/16" inserts (36" long): 18"

[I said the crown on my Sarns bullnose (36" long plates) was 15-16". The crown is right, but the runners are only 30" long, not 36". ]
Angles: unknown

The next thing is the lead-in and lead-out. The leading
edge of the runner has some curve or angle to it which is
usually fully rounded over, and extends about 4" back from
the very front of the body. As the leading edge gets near
the ice, there is a transition to the sharpened edge. The
most significant change in this transition is where the
radiused (rounded over) edge changes to a sharpened angle
(roughly 90 degrees).

Behind this transition region is what I usually refer to as
the "lead-in", where the sharp edge has been dulled to
varying degrees (very dull right behind the transition).
It helps to have a light behind the runner when viewing the
crown and lead-in/lead-out. With the runner on the straightedge,
you can visualize where the lead-in starts. At the start of
the lead-in, most of my runners have about 3/16"-1/4" clearance.

Lead-out is very similar to the lead-in. The very back edge
of my runners is completely rounded over. Between this point
and 4-5" or so forward, the edge changes from being fully
rounded to sharp. This section which has been dulled is what I
call "lead-out". Near the trailing edge (1" or so from the very
back) my runners have about 3/16" clearance and are very dull.

Hope this clears up some of the questions. Post another
question if something is still puzzling. I don't believe
anybody REALLY has all the answers to runner design, even
though you'll find plenty of people who think they do.
If you think my analysis is all washed up, I'd love to read
those opinions too, I'm certainly not done learning how to
make fast runners faster yet...

Sharpening

690

Posted by: Tim Polaski on July 15, 2002 at 15:25:25:

Hey guys and gals,

How do I learn to sharpen runners??? I sailed my new DN only 2 times last season and I haven't touched the runner edges (except to oil them). I have Sarns bullnose runners and I want to learn how to sharpen them RIGHT so I don't screw them up. Also thinking about making some inserts this year or over the winter. If you buy sharpening stones, do they come with instructions? Is there a good article in reprints or any Runner Tracks that addresses this for a novice? No rush on this and thanks for all the good advice from you guys in the past when I was building....it turned out GREAT.

Tim Polaski
DN 5203

691

Posted by: Geoff Sobering on July 15, 2002 at 22:57:54:

In Reply to: Runner Sharpening posted by Tim Polaski on July 15, 2002 at 15:25:25:

I believe that "Think Ice!" has a section on runner sharpening (I can't seem to find my copy, so I can't check...).

IMHO, the best way to learn this skill is to have someone demonstrate and give some pointers; I was lucky to find a great group of ice-boaters here in Madison, WI who helped me learn the basics, and then made sure I didn't screw up too badly until I was past the beginner stage. If at all possible, I'd suggest trying to hook-up with some local experts and get some hands-on help. If you're in the Madison area, I'd be happy to give you a hand.

Cheers,

Geoff Sobering
US 5156

Snow Blades

551

Posted by: Stephen Jeffery on February 12, 2001 at 01:31:12:

In Reply to: Snow blades for DN posted by Stephen Loomis on November 07, 2000 at 22:43:13:

Stephen,

I have a set of Fibre glass skiis that were built by a company called Price Ice boats near Ottawa, Ontario.

They do not have any steel in them and are only good for running on top of fresh snow. They are also very heavy. I have put them to use on Lake Simcoe a few times and I wasn't very impressed.

I think they could help stretch the ice boat season a bit if you used them on really windy days.

Cheers!

Straightening Bent Runners

111

Posted by: John on November 29, 2000 at 07:59:33:

Greetings all,

I know that a bent plate runner is a perfect excuse to buy a nice set of
inserts but I would like to try and fix them.

Couple questions:

1) What material are they made of?
2) How best to straighten?
3) Do they need to be retempered after bending back?

Thanks all

John DN 5023

112

Posted by: Paul Goodwin on November 29, 2000 at 11:47:20:

In Reply to: straightening bent Sarns plate runners posted by John on November 29, 2000 at 07:59:33:

John,

Sarns runners are made of medium-carbon steel (normally 1060 if I
recall correctly), and the edge is induction hardened. The hardened
section extends from 3/4" - 1" from the bottom edge. If you look
carefully, you can frequently see where the transition is from hard
to soft because of a slight difference in surface finish during
grinding.

Depending on how badly the runner is bent, you could have two
conditions to worry about: the plate itself being bent, and the
stiffener being bent. I would recommend removing the stiffener, and
dealing with the two components seperately. Recent (the last 20 years
or so) the stiffener has been held on with large roll-pins. Just
drive out the pin to remove stiffener.

If the stiffener is only slightly bent, you should be able to
straighten it without much problem. If it has a severe bend, it will
be work hardened, and will harden more as you try to straighten it.
This causes the aluminum to want to bend someplace other than where
you expect. But, you'll just have to try and straighten it and see
what happens.

If the plate is bent, then the soft part of the plate has taken a
"set", and is holding the hardened edge in a curve. Check the
hardened edge for cracks. If the edge is cracked, then your runner is
probably doomed. If it's not cracked, then you should have no problem
straightening it.

You can straighten either the plate or stiffener in the home shop.
What I do is place two wood (or metal) blocks on a good thick
workbench, and place the part to be straightened on top of the blocks.
Center the curve between the blocks, with the convex side up. Use a
large c-clamp in between the blocks to force a reverse bend. Keep
increasing the amount of reverse bend until the part has been
straightened. A good way to control the amount of bend is to put a
shim under the part, and clamp until you contact the shim. Reduce the
thickness of the shim to increase the amount of bend. This will give
you a nice repeatable method.

There is no need to temper the runner afterward, since no heat was
applied. You could anneal the blade 1st, but this hes not been
necessary in my experience. Of course if it is annealed, then it would
need to harden and tempered. It would be a lot less grief (and
probably less expensive) just to get a new runner!

A couple of hints. The closer together you place the blocks, the
tighter the radius of the bend. The sharper (smaller radius) the bend
is you are trying to remove, the closer you have to set the blocks.
The closer the blocks, the more force it will require with the
c-clamp. Start with the blocks pretty far apart (maybe even at the
front and back of the full-height portion of the runner). This is a
judgement call, and I can't offer a lot of guidance. However, it's
not rocket science, and the runner is already bent, so what the
hell... give it a try!

119

Posted by: Bob Dill on December 17, 2000 at 09:09:16:

In Reply to: straightening bent Sarns plate runners posted by John on November 29, 2000 at 07:59:33:

Straightening Runners

Paul Goodwin’s suggestion for straightening Sarns plates(soft steel with a hard edge) is excellent. I would even go farther to say that if the hard edge is cracked that runner will probably work fine after the runner is sharpened.

Straightening hardened runners are another matter. A few years ago Don Brush had some 440c runners heat treated by someone who was not able to keep them flat. We tried straightening them in a press. It was amazing to see how much deflection we could put in them with no effect on straightness. We found the yield point on the first runner and were able to straighten it. The next couple got to the tensile strength first resulting an instantaneous loss of $75 for Don. (We tied the runner ends with rope to keep the pieces form flying around if it broke). We finished up with two straight runners and a $225 loss for Don.

Peter Hill, when faced with the same problem, came up with a good answer. If you peen the concave side of the bend it will expand the metal slightly. We had found that a ball peen hammer was not enough so he got an electric jackhammer with a peening end and went to work with the runner on his basement floor. The higher hammering force and rate straightened the runners very quickly. Peter did this with fully hardened 440c. If you are working with hardnesses above Rc55 this might not work as well. Needless to say this is extremely noisy. Wear a GOOD of hearing protection.

Note: Hammer peening may work for softer steel like the bulk of the Sarns plates.

Bob

752

Posted by: Don Meserole on January 06, 2003 at 09:41:17:

A few years ago someone, (Paul Goodwin?) wrote a article about how to straighten bent runners. My search through past IDNIYRA newsletters for the article was unsucessful.

If memory serves, the technique involved a large ball peen hammer, ear plugs and the runner on a flat surface with the concave side up....
Suspect the article was directed at plates, however it is possible that some of us may have removed alum. stiffeners from inserts and gone sailing.
Anyone out there had success straightening inserts?

753

Posted by: Randy Rogoski on January 06, 2003 at 11:56:30:

In Reply to: Straightening bent runner posted by Don Meserole on January 06, 2003 at 09:41:17:

In Reprints #1 there is an article by Wim Van Acker originally published in Runner Tracks in 1987 titled "Corrections of Plate Runner Distortions." This article is on page 93.

It talks about how to correct the distortions that occur in plate steel caused by using a metal shear to cut the plate to make the runners.

To my knowledge, there has never been anything published about straightening a runner after it has been bent in an accident, and I have every Runner Tracks since 1972.

Randy Rogoski
DN US 4192

754

Posted by: Bill Condon on January 06, 2003 at 15:55:27:

In Reply to: Straightening bent runner posted by Don Meserole on January 06, 2003 at 09:41:17:

Don: We have had good success in flattening a bent runner by taking an air hammer with a blunt tip and running the tip across the runner on the concave side. You are trying to "stretch" the metal to remove the warp. I've usually tried to keep the peening on the upper half of the runner which will eventually be put into the runner body. Do not sand out the peening marks as it will return to the previous bend. Ear protection is a must. We have done some severely bent runners with good success in a few minutes.

Correction: Should always proof read these damn things more than once! Anyway, start the peening at the middle spot of the bend and work your way out toward the ends.

756

Posted by: Paul Goodwin on January 07, 2003 at 11:25:49:

In Reply to: Straightening bent runner posted by Don Meserole on January 06, 2003 at 09:41:17:

The articles you're remembering were posted here on the bulletin
board. Two articles on this subject are in the "Open Forum,
Technical Discussion" archives. To get to the archives, click
on the heading of the section.

I wrote the first posting which dealt primarily with straightening
Sarns type runners (soft steel with a hardened edge):
http://cerebus.winsite.com/laser/DNboard/mesgEuro/112.html

This was followed up by Bob Dill with some good comments on
straightening fully hardened runners (typical of 440C inserts):
http://cerebus.winsite.com/laser/DNboard/mesgEuro/119.html

Brakes

217

Posted by: Roger Livingston on December 31, 2001 at 08:40:45:

In New Hampshire this weekend, a number of boats came off their brakes due to the puffy wind conditions. This made for a very dangerous situation. This seems to happen with rear brakes only. To remedy the problem, I drill a hole in back of the brake bar with the brake down. Then I insert a quick release pin whenever I park my boat.

Articles

302

Posted by: Geoff S. on March 25, 2003 at 17:37:17:

In Reply to: Runner diagram posted by Doug on March 25, 2003 at 08:38:30:

I grabbed a copy of Jan's files from the Yahoo group section and sent them off to Doug. If anyone else needs the files and is having toruble with Yahoo, drop me a note and I'll forward them on to you.

Just FYI, here are the links to Jan's and one to Dan Schutte's articles on runners:
http://groups.yahoo.com/group/IceBoating/files/Insertrunnercrownplans.doc
http://groups.yahoo.com/group/IceBoating/files/runners.doc

Masts

810

Posted by: Bob Rast DN1313 on June 20, 2003 at 22:59:04:

In Reply to: prefered spar posted by rob L on June 15, 2003 at 20:51:45:

The preferred spar is presently Fiberglass or Glass carbon composite.
There are several good manufacturers. Ron Sherry has built more than anybody, and Jeff Kent plus various others custom built by individual Sailors. The preferred mast is going to be what you want it to be or maybe not. You need to consider your weight and the mast deflection. Lighter Skippers need a softer mast Heavier need Stiffer.
The older Fiberglass masts are still going strong and you rarely see any failures. If you can find a used one try it. The glass Carbon masts perform relatively the same but weigh less close to minimum. I built several glass carbon masts that weighed 14lbs. When building all glass they come in around 18lbs. The Carbon does have that all desired look. Performance wise they both will get you going and then you need to figure out how to rig your boat to get optimum speed. Also look into a newer sail for fiberglass masts and as usual you will have several choices. Good Luck

Getting started in the class

161

Posted by: Paul Goodwin on July 03, 2001 at 07:53:45:

In Reply to: NEW TOPIC: Mast for new DN posted by Tim Polaski on June 29, 2001 at 15:06:43:

I don't think you'll find much argument that the performance ranking
would be 1) composite; 2) wood; 3) aluminum.

The composite mast was developed because racers were bending their
masts to the limit and beyond during racing. The fequent breaking of
wood masts lead the class to allow composite masts, with their much
longer life expectancy. Actually, a good composite mast can bend
further than required for performance reasons (at least with current
sails), so there is an adequate safety margin before breaking. I sail
my equipment very hard, and haven't broken a composite mast yet, even
with four seasons of sailing on a single mast (I used to break 1 or 2
(or 3) wood masts per year).

As far as alternatives, the wood mast is clearly superior to an
aluminum mast from the performance aspect. If you can build one
yourself, wood is also much cheaper (I was building wood masts for
around $130 in materials 5 years ago). If you need to have someone
else build your wood mast, the cost is likely to be in the same range
as buying a composite mast, and the wood mast no longer makes sense.

There is an advantage to the aluminum mast - the "aluminum mast/plate
runner" fleet. The IDNIYRA class has encouraged, and many regattas
have, an aluminum mast fleet. This fleet is also usually restricted
to using plate (Sarns style) runners. The idea is to have a less
expensive alternative, especially for juniors and new racers.
Unfortunately the concept has never really taken off, but there are
usually a few participants at the regattas I've been to, with there
own trophies. The aluminum mast fleet races with the rest of the
boats, and sometimes place quite well against the standard boats,
particularly in light wind.

If you decide to build a wood mast, email me for some tips that were
never published (webmaster@idniyra.org)...

352

Posted by: Jeff Pittel on December 30, 1998 at 09:55:28:

In Reply to: Mast construction posted by Don Sitter on December 29, 1998 at 16:53:14:

For an older DN, Aluminum is the most economical way to go (around
400.00 ). Fiberglass/Carbon are the fastest and most durable but they go for 1000.00+. If you are handy with wood, a hollow wood mast of the Paul Goodwin design (mast shown on the current plans in the I.D.N.I.Y.R.A yearbook) should cost around 200.00 to 300.00 to build. Check the supplier list in this website for a mast that you decide on.

456

Posted by: Ed Atkeson on December 22, 1999 at 09:56:07:

In Reply to: About this bendy-ness thing... posted by A. Brown on December 19, 1999 at 14:54:44:

A. Brown:
>>> I do not own a DN, but I've considered buying one before. What I am wondering is what is the purpose behind having the runner plank and the mast so bendy? How does that make for a faster ice yacht? My gut reaction would be that all the flex would absorb potential forward energy instead of utilizing it. This must be wrong since everyone has flex in their rigs, but I don't get why.
--------------
Dear A.
Hmmm, I'm on thin ice here, I'm not the expert, but some thoughts:
I think the main advantage of flexibility in the DN design is not having to change your underwear as often.
There's two things, 1.) The DN is so small and lightweight, you need the flexibility for control and some small measure of comfort. 2.) A flexible mast makes you go fast because of the improved sail shape it gives you.
It's good that the plank is springy, you get a slightly less terrifying ride. These things go 60 over bumpy ice without upsetting. If the plank was rigid, the whole boat would jump whenever the runner hit a bump, the runners would be off the ice half the time, you'd have a lot less control of the boat. If ice was perfect, the DN would probably have a stiffer plank.
If the plank was stiff the boat would blow over quicker in a puff. Some of the energy of a puff is absorbed by the springy plank, letting the boat tilt a bit to windward, dumping some wind, letting you stay on course instead of dealing with a sudden hike.
From what I've heard, boats with bendy masts seem to want stiffer planks, the energy is absorbed by the mast. And this is where I think you're right: if everything is flexing too much you won't go as fast.

The masts used to be stiff. The bending happened by accident. Someone noticed that you go like hell just before your wooden mast turns to splinters.
What mast bending does is it flattens the sail. The DN goes fast because of high speed apparent wind going over the sail. There's an airfoil effect -- picture an airplane wing turned on its end. Normally, it's not humanly possible to pull the sail tight enough to get rid of the belly and twist in the sail enough to get the optimum airfoil shape. When the mast bends, you get a curved leading edge, but a better airfoil cross section of the sail, which I guess, really puts you back in the leather.
There's another comfort factor here, you don't have to pull so hard on the sheet to get a good sail shape.
When you're already going fast, and get hammered by a puff, the mast bends sideways below the hound, lowering the center of power of the sail, making you go forward rather than hiking you up.

Have I got this right?
Ed A

459

Posted by: Mark Kiefer on December 22, 1999 at 15:23:04:

In Reply to: About this bendy-ness thing... posted by A. Brown on December 19, 1999 at 14:54:44:

I can't profess any true knowledge about the what really is happening in an iceboat, but having said that, I think we can frame out the arguements and let others fill in what they know about this bendy-ness thing.

1. Mast bend: there are two functions that seem to be served by a bendy mast: A. when the middle of the spar sags off to leeward it takes a good deal of twist out of the sail, causing a noticable improvment in speed and pointing. (very significant) In many conditions, the first person to get the spar out of column is way out in front. B: Gust Onslaught: Nobody has the reaction time to ease a sheet on the ice, The rig must self adjust (largely) in order to absorb the loading from a gust.

2: Plank bend: Again, part is for absorbing gust energy, part is from tradition, and part is it jsut feels right. There are more and more sailors competing with stiffer and stiffer planks, but plenty of fast sailors with limber planks. There may be an arguement that a looser hull & plank may attenuate the modulation in the sail,caused by ice imperfections, increasing lift and perhaps a decrease in drag.

Mark Kiefer
US 4695

460

Posted by: Bill Braden on December 22, 1999 at 22:26:34:

In Reply to: About this bendy-ness thing... posted by A. Brown on December 19, 1999 at 14:54:44:

A Brown wrote:
What I am wondering is what is the purpose behind having the runner plank and the mast so bendy?

If an iceboat with a bendy plank goes over a bump, the runners
go up and down, the hull stays level. With a rigid plank, the
hull would be forced to move up and down as well, wasting even more
energy.

The mast bend can be controlled -- more bend, flatter sail,
less power but less drag for high wind; less bend, fuller sail,
more power and more drag. See Think Ice for details of factors
influencing mast bend.

Shipping a mast

226

Posted by: Doug G on February 06, 2002 at 10:48:09:

In Reply to: Advice on shipping a mast posted by Mike D. on January 12, 2002 at 08:48:01:

Here in Prince Edward Island, on the east coast of Canada, my buddy and I bought 5 aluminum masts from somewhere in Illinois (or Alaska - Wayne, my buddy, or the guy we bought from will correct me). The FOR SALE actually came from this board a couple of years ago.
We had them trucked across the continent and it was quite reasonable.
The seller wrapped them in cardboard and blister pack, they arrived almost perfectly intact, there was a small dent in one of them, but there was no indication that it was from transport. And it was reasonable cost - maybe because it shared over the 5 masts.
Also I shipped 12' toerail, not for my DN, from Victoria BC to PEI, from the Pacific to the Atlantic and it would fit in the cargo hole of an Air Canada jet. The airline people said only a jet would have a cargo hole long enough. That was two years ago and was only $75 Cdn from his airport to my airport, with a shipping weight of 25lb, in two days.
Thus ends my two cents on shipping across borders and across nations.

Rules and Discussion

229

Posted by: Bruce Lowstuter DN 4580 on February 08, 2002 at 09:36:36:

The only competitive mast for the DN today is a composite mast. Why don't we as a class include it in the official plans? This is a class that prides itself on home built boats. Yet there are no plans for the home builder on how to build a fiberglass or carbon fiber/fiberglass composite mast (at least I have not found any). If there is a set of plans out there please let me know. I have been a DN sailor since 1989. I build my boat using a combination of Norton and Gougeon plans, bought a Norton Aluminum mast and then later built a wood strip mast from ash. Now it seems that I have to upgrade again to a composite mast. The last time I sailed was very discouraging for me. The new masts can point 5 or 10 degrees higher than the wood masts - no way to compete with that!

I just read Randy Rogoski's Timeline of North American Ice Boating. Great job Randy by the way. But in the last section he said "2001 - Non-composite DN masts obsolete for racing". He's right - they are.

So, now its time to stop ignoring the 800 lb gorilla thats sitting in the middle of the room.

Would somebody please publish step by step plans and a lay-up schedule that will allow a home builder a chance to build a competitive mast? To not make this info availible harms the class. I'm close to dropping out. From what I'm reading here on the forum there are also others who are frustrated with the situation and are dropping out. Why are experienced sailors leaving? This is it!!!

Sorry for being so negative in this message. I have had a lot of fun in my DN and have very much enjoyed the sport.
I also think the guys who have developed the new mast technology should be given lots of credit and accolades. They deserve honorable mention in the DN history books.
Ron Sherry and Jeff Kent have done a great job developing these new masts.
But guys, it's time to publish the plans and the process.
There will always be lots of people who won't want to build their own and that will want to buy masts from proven expert mast builders. It won't hurt your long term business. You guys are here to stay. What it will do, is to keep people from leaving the class. And, thats a good thing.

Bruce

230

Posted by: Bob Rast DN1313 on February 08, 2002 at 13:44:28:

In Reply to: Official DN mast plans are a joke posted by Bruce Lowstuter DN 4580 on February 08, 2002 at 09:36:36:

Bruce sorry for your frustration with the current state of class mast construction and availability of plans. I understand your position as I was also frustrated with the class after the Experimental mast program back around 95 or 96? At that time the class allowed a number of people to apply for a permit to develop a new mast and construction method that would be more durable then the wooden masts. At the end of the trial I thought that the Intent and purpose of the program was to publish some type of summary and show the class options for building a more durable mast. I think this question should be addressed by someone on the technical committee as they may have access to the original content and proposal concerning the experimental mast program. Any way there are a number of people building thier own composite masts and Depending on where you are located you might want to work with someone to build a mast or develop a program. Building a composite mast is not that difficult and can be done several different ways. 1.Hand layup on a male mold such as a foam core, or wooden plug and 2 Blow molding in a mold from the inside , or laying up 2 halves either vacuum bagging or by hand. A building a mold is probably the biggest investment and the Gougeon Bros have several good articles on mold making and vacuum bagging. If you want to build your own it is some work and will take several tries to find what works for you. I have made 19 masts to date with some other friends in Wisconsin and we still come away from major regattas scratching our heads when a guy shows up with a production mast new or older (Sherry or Kent) and out sails us when we spend so much time building and tweaking lay-up schedules and trying to find the magic combination. You may want to invest in a used fiberglass mast or new one otherwise the cost of developing a mold and building is going to cost as much. They are durable, we have only broken 1 out of 19 masts and that was #2 and In the last couple of years I can only remember 1 or 2 fiberglass masts breaking.

231

Posted by: John Dennis on February 08, 2002 at 13:46:52:

In Reply to: Official DN mast plans are a joke posted by Bruce Lowstuter DN 4580 on February 08, 2002 at 09:36:36:

With the new mast dimension rules, I do not think that a home built mast made from a combination of wood carbon and fiberglass is obsolete in any way. A spruce strip mast with ash in the critical area, a bit of carbon on the inside and a bunch of unidirectional glass on the outside for example.

The real reason most of us are not building our own masts anymore is the amount of effort it takes. I am still sailing a mast that I bought in 1997. That mast happens to be a whip (#19) and at this point seems to be as good as it was the day I bought it.

For the price, these commercially available spars seem to be a better value then the mast you can build. Your time and effort suddenly shifts toward your runners and the next thing you know, your program has jumped to a new level. Oh ya, and your having more fun.

If you want to build a molded mast, the first thing is to build a mold. There are many good books on the subject including a publication put out by the Gugeon brothers. A Norton Wing with the top split and tapered will work as a plug. The glass is wetted out and laid in the bottom half of the mold. An inflatable bladder is place on the glass and the glass is wrapped over the bladder. With the top of the mold in place and clamped the bladder is inflated.

One of the guys in our club has made some really good masts in his garage this way. It takes practice however.

232

Posted by: Jeff Soderholm on February 08, 2002 at 15:30:17:

In Reply to: Official DN mast plans are a joke posted by Bruce Lowstuter DN 4580 on February 08, 2002 at 09:36:36:

The production masts, specifically the Kent or CSI, are durable and are wonderful to sail but definetly are not unbreakable. My mast built in 1997-98 just experienced a catastrophic failure recently. Seven feet up from the deck the mast was flexed out fully compressed and the outer wall apparently couldn't elongate any further when a gust hit and BOOM!!! It failed. Now just a very expensive basement fixture. I am now in search of a suitable replacement.

233

Posted by: mark kiefer on February 08, 2002 at 15:30:51:

In Reply to: Official DN mast plans are a joke posted by Bruce Lowstuter DN 4580 on February 08, 2002 at 09:36:36:

Here's $0.02 from west of the mississippi.

As JD and Bob suggest buiilding a competitive glass mast is a bit of a challenge, even with a good tool and 5-6 iterations of practice. We've all built a couple.

Both also raise the compelling price and comptitive values of commercially available spars. Most of us are now using "store bought" spars for these reasons and one more reason, the most compelling one I can see:

All of the good guys are buying masts and spending their time working on their runners, THIS IS REALLY IMPORTANT. ALL OF THE GOLD FLEET IS STORE BOUGHT. We all see the importance of working on runner programs, and getting nine perfect will take you quite a while, If you're going to spend 200 hours elbow deep in "gouge" your competitors will have on average, at least a 200 hour opportunity advantage over you in the runner department.

If you want to build spars, there are plenty of guys who've built glass & glass carbon spars in several construction methods, we'll all give you enough contradictory information to totally confuse you

Mark Kiefer

234

Posted by: Bob Rast DN1313 on February 08, 2002 at 17:29:41:

In Reply to: Re: Official DN mast plans are a joke posted by mark kiefer on February 08, 2002 at 15:30:51:

Ok here is the real story, names will be withheld to protect the innocent. Our first adventure in fiberglass mast building some where back in 95, I was going to layup a mast with some buddies who will remain anonymous because they both hold a high positions with various DN organizations and Initials are LL and BC. We started by mixing epoxy in a 2 gallon bucket. My friend said , I saw Ron mix up a whole gallon batch at once. As we were wetting out the second layer he said the glue looked a little stiff. As we glanced over at the bucket there was smoke comming out and quickly threw $90. bucks worth of glue into the weeds. Lesson one if you mix a gallon of goeuge dont forget the hot dogs and buns.Another gallon of glue and we finished a mast that was deformed and was sold some where as a flag pole. Mast 2 came out fine lasted one tack in the NIYA before I broke it I was going good to. . Mast number three built carefully following all details to avoid previous mistakes came out too stiff I couldnt bend it, After going at it with my belt sander it would bend a little didnt like it sold #4 wanted a mast that would bend for my weight 160 lbs so we left out some glass. I cut weighed and numbered each layer of cloth before we started, when we finished and all the guys left, I went back down to the shop and found 1 layer of glass had rolled of the scale and didnt make it into the mast. Very bendy mast known as the Pistakee Mistakee if you were there you will remember it wouldnt rotate so I layed it off till the hound practicaly hit the ice,added gobs of carbon S2 s glass sent to unknown destination.so lets see Mast 1 junk . build mold several hundred bucks. Mast 2 one ride 2 piece mast ,mast 3 too stiff sold, mast4 didnt rotate gone,Mast 5 and 6 look good Ill keep them for a while. total cost More than a Sherry mast , Time spent with friends away from family Priceless.

235

Posted by: Bruce Lowstuter on February 08, 2002 at 22:49:00:

In Reply to: Re: Official DN mast plans what not to do posted by Bob Rast DN1313 on February 08, 2002 at 17:29:41:

Bob,

Thanks for your input and sharing your fiberglass mast building horror stories. The experience you have gone thru is exactly my point. I don't want to build 5 masts before one of them comes out right. I love iceboating but with all the other financial priorities that I have in this life, I really can't justify spending $1000 to $1500 on a new mast and another $500 on a new sail. Maybe in some other life I'll have lots of excess cash and can buy all the toys I want - but not in this one. As it turns out, my wife has some priorities, too, which don't involve pointing higher in a DN.

It has been a year since any serious mast building discussions have taken place on this forum. Jeff Kent wrote some interesting posts in late 2000, which described a basic lay-up schedule. Jeff, I like what I have seen of your stuff. I like the idea of a male mold (or male mandrel) and wrapping internal carbon layers for hoop strength. This is the same concept that is used for filament wound tubes and would seem to yield a more durable mast than a female mold and an internal pressure bag. By the way, Jeff, I agree that Kevlar should be allowed in DN construction. It's not any more exotic than any other materials we use.

So, one of my first questions is how to build an economical male mandrel. Has anybody found an easy (and cheap) way to build one?
A 16 foot polished aluminum mandel is overkill for the home builder. Also, should it rotate or be in a fixed position? Any thoughts?

Let me also apologize if I offended anyone with my earlier post.
I re-read what I said this morning and I guess I sounded pretty harsh and judgmental of the class. My intention is twofold: yes I want to learn from other people's experience and build a good mast on the first attempt, and I also want to open up an important topic that, it seems to me, people have been avoiding.

Please, let's have a serious technical discussion about fiberglass/composite mast construction.

Respectfully,
Bruce Lowstuter DN 4580

237

Posted by: Bob Rast on February 09, 2002 at 09:17:22:

In Reply to: Re: Official DN mast plans what not to do posted by Bruce Lowstuter on February 08, 2002 at 22:49:00:

I built one of my first fiberglass masts on a male plug made from a recently broken ash mast, It still hangs in my basement as I cant find any buyers at swap meets who have the desire to build . It looks like the interior of the mast with a half round area were the tunnel goes. I layed up 1 layer of plain weave cloth then glued on the tunnel, after that I added about 6 to 7 layers of biaxil and s glass cut the mast off the plug cutting through the sides and glued it back together. The plug was rigid enough to mount it above the bench with threaded rod glued in each end so I could rotate it,If I was going to hand layup I would use more carbon to save on weight cost more but lighter. You might want to shrink wrap with packaging wrap to squeeze out excess resin otherwiseit will be heavy . I have found it is better to cover your project first with some 6 mil plastic sheet and then wrap carefully which will produce a much smoother surface otherwise the shrink wrapwill stretch and get stuck in the resin.Vacuum bagging would work well but you need a pump etc. My original plug was well tapered with the idea that if I used enough PVA release which is water soluable , I could inject water and slide mast off Its available if you can get to WI. Real cheap any way good luck.

236

Posted by: Randy Rogoski on February 09, 2002 at 03:35:06:

Marty Fredericksen, Art Balzer, and Mark Burns from the West Michigan Ice Yacht Club have built 13 composite masts in Marty's basement. The first step was building a mast plug, and from that a mold was made. Composite masts are a project suitable for a club, since to tool up to build just one is not practical.

Our club has also built the tooling and fixtures to mass produce insert runners too. It's now practical to build just two. When we started, we geared up to build 30. We've got a system.

The glass lay up schedule is the real challenge. Ron Sherry has got it right. The WMIYC is still working at producing a mast that can come close. It's the mast sail combination that makes the DN go, on the correct set of runners for the conditions.

The masts that Marty and friends produce look good, and to date not one has broken. They sell them for $850, $750 for club members. Email Marty at: spin4641@attbi.com(Marty FREDERICKSEN.

Aluminum masts

Internal reinforcement

278

Posted by: Frank Mcgreevy on November 13, 2002 at 11:15:02:

I am running a norton aluminum mast. At the Williams Bay swap meet I believe it was Skip Boston I was talking to sitting just inside the bay door about reinforcing the mast with a wood insert. I currently have a closet coat hanger bar inside and he said to replace it with a TIGHT fitting insert to prevent kinking the mast when it over-bends. I forgot to ask how far up the mast should the insert go? Any advice would be greatly appreciated by this novice day-sailer.

279

Posted by: Ken Smith on November 14, 2002 at 01:08:06:

In Reply to: NEW TOPIC: re-rod posted by Frank Mcgreevy on November 13, 2002 at 11:15:02:

Depending on the mast, its wall thickness and state of fatigue, the extruded aluminum tube's first failure mode on the DN is by taing a permenent set in bending. You will notice that the mast only wants to be rotated to one side.

The second failure mode is the compression (Concave) side wall kinks by a diamond shaped panel popping in. If you tack and get the mast to bend the other way, it will break in half at the kink.

The third failure mode is a fold starting at the compression side and causing a "plastic hinge" as the mast folds in half.

The fourth failure mode is when the mast falls off the top or your car onto the highway.

The first three can be delayed with a reinforcing rod extending from the base a foot and a half or so past the half way point between hound and base. The rod adds to stiffness and helps hold the sidewalls appart, slowing formation of kinks and folds. All these are buckling instability related failures due to combined mast compression and bending. Preventing the fourth requires use of adequate tiedowns. Aluminum masts will suffer one or more of the above if they are transported often and sailed hard.

280

Posted by: Roger Livingston on November 15, 2002 at 10:33:26:

In Reply to: NEW TOPIC: re-rod posted by Frank Mcgreevy on November 13, 2002 at 11:15:02:

I bent a Bryant aluminum mast a couple of years ago. Bryant suggested the insert for the new mast and sent some plans. It was just a 3/4 inch thick piece of wood cut to the inside width of the mast. The length is extended to the hound. They recommmended some spaces to hold the stiffener in the center, but I found this wasn't necessary if you make the fit snug enough. Seems to work.

Composite Spars

372

Posted by: US 5174 on November 24, 2003 at 22:47:00:

I was wondering how long the production spars last the ones that Jeff Kent and Ron Sherry produce. And what has cause the them to break. I know that some are made from glass and some from carbon does they make any difference on how fragile they are. Is the carbon faster than glass with the right sail.

373

Posted by: Bob Rast on November 25, 2003 at 00:24:06:

In Reply to: longevity of production spars posted by US 5174 on November 24, 2003 at 22:47:00:

The current fiberglass masts seem to have a long life expectancy. Early in the development stages when they first came out there were some failures possibly due to a gliches in production or overzealous sailor. There are a lot of good used fiberglass masts out there and most sailors have been using the same for a number of years. We have built about 20 masts using the same method as Ron and broke the 2nd one and the last one.Both failures we due to production differences.As far as performance thats up for debate Im sure you will get different opinions. The carbon masts are not all carbon but 90 prcent glass and maybe 1 or 2 layers of carbon. Both perform about the same. the big differnce is in weight savings. early glass masts were about 18 lbs I have built several with carbon that come in under minimum around 14lbs.Need to add weight to be class legal at 15lbs.

Mast Bend

638

Posted by: David Wilkins on February 25, 2002 at 16:56:57:

In Reply to: This is starting to sound like a really good idea posted by Bruce Lowstuter on February 24, 2002 at 07:23:57:

Bruce,

As far as mast bending. Between hound and heal with 100lbs I'd prefer it to bend like 1 9/16" - 1 5/8". The for and aft amount is much more up to debate. My masts basically bend as much overall for and aft as they do hound to toe side to side. Play with mast rotation to fine tune power and sail 'set'.

D. Wilkins

641

Posted by: Ken Smith on February 28, 2002 at 07:54:22:

In Reply to: Mast bending posted by David Wilkins on February 25, 2002 at 16:56:57:

Having spent some time with some very fast Polish team members, having built wood and glass masts, and having sailed many masts, the following are posted for what its worth:

1. There is nothing magic about glass vs wood vs wood/glass vs glass/wood/carbon mix. If done right and matched to plank, sailor weight and (most important) sail, (even more important--sailor skill) any construction method can be very fast. Glass/carbon composite masts just usually last longer than wood if they are sailed in extreme bending. All combinations were found on boats in the Gold fleet at the worlds. One heavy sailor in the gold fleet at the worlds prefers a wood/glass mast and has a stock of them for future use. He broke one at the regatta. Most every combination of soft tip, stiff tip, and lower stiffness was seen. But the skippers all made the masts bend when sailing up wind to be fast.

2. A fast mast will bend out six inches to a foot or more when sailing upwind. In light air and smooth ice, a softer mast is fastest. In higher wind and smooth ice, a stiffer mast is fastest. In sticky ice, a more moderate mast is fastest. This is subject to debate. Only one mast per regatta is allowed.

3. At the worlds, there was some discussion heard about "if we can have more than one sail, why not more than one mast" UGH.

4. When your boat is hit by a gust, something flexing reduces the tendency to hike and causes the boat to accelerate. The something flexing can be the plank, the mast , the hull or a mix of all the above. Most seem to prefer a stiffer plank with a more flexible mast, but some like to see everything flexing. Soft plank, soft mast etc.

5. If you mast bends too little, the boat will want to hike in a gust. This may be made to be fast, but it takes work on the sheet line to be fast like this.

6. If your mast bends too much, you sacrifice pointing ability and are a little slower down wind.

7. Moving the mast step forward, loosening the side stays, and increasing the mast rake all cause any mast to bend more. The opposite does the opposite.

8. Diagonal fibers on a mast help keep the mast from folding in half. This is important between the hound and base. Straight fibers oriented along the mast have the most effect on stiffness per unit of added fibers.

9. If the DN were an Olympic class, how many mast/sail/runner combinations would be required to be competitive in all conditions? UGH UGH.

Measuring Mast bend (deflection)

643

Posted by: Paul Goodwin on March 01, 2002 at 20:24:32:

In Reply to: Deflection ranges for "soft", "moderate", "stiff" masts? posted by Bruce Lowstuter DN4580 on March 01, 2002 at 07:32:11:

Hi Bruce,

I wrote an article on measuring mast deflection which
includes plots of three masts which fall quite nicely
into what could be considered "soft", "moderate", and
"stiff" classifications. The article was written in
1990, but I think the wood mast values would still be
a good target for most people.

This article is posted on the IDNIYRA website, along
with some other worthwhile articles. I assume you're
not aware of the site or you wouldn't be asking this
question. You can see the article by going the "Articles"
page of the website and looking for "Measuring Mast
Stiffness". You can get to the IDNIYRA website here:
http://www.idniyra.org

You asked for a deflection with a "standard" weight.
As explain in the article, I don't think this is the
right way to measure a mast. If you really want to,
you can figure out the deflection at 100lb from the
stiffness numbers listed in the article. If you have
problems with this let me know and I can calculate it
for you.

The "stiff" mast is a Kenyon 2040 wing mast, which was
the best mast available for medium to heavy sailors at
the time.

The "moderate" mast is a Norton "wing", and was the
softest aluminum mast available. It was very fast
for light to medium weight sailors, but was prone
to kinking if it bent too far, which it did easily.
This led to the DN class allowing aluminum masts
with wood stiffeners inside.

The "soft" mast was measured on a very good wood
mast built of redwood and white ash. This stiffness
was the benchmark for developing Ron Sherry's very
successful fiberglass masts, although we went for
slightly less stiffness fore and aft.

I would aim for getting your stiffness close to the
redwood/ash mast, except a little more limber fore
and aft (more like the Norton wing). If you look
at the plots, you will see that the wood mast is
the most limber in side bend, but the Norton wing
was more flexible fore and aft. While the high fore
and aft stiffness helps the mast to rotate easily,
it detracts from the overall performance.

646

Posted by: Paul Goodwin on March 12, 2002 at 08:30:16:

In Reply to: Have you measured your own mast lately? posted by Bruce Lowstuter on March 05, 2002 at 05:24:28:

I haven't measured any masts in the last couple years,
mostly because mine is still working fine and I see no
real reason to change anything.

What's "mine"??? -- a three year old "Whip" from Ron
Sherry. I haven't notinced any significant change in
stiffness over the years, although I know enough about
glass composites to assume the stiffness is lower now
than when it was new. I will measure my mast and see
how it compares to the data that was published (oh so
many years ago now...)

As for other masts, I don't know of any "top gold fleet
wood masts" in N. America, I've never measured a Kent
mast, and I have no idea what mast Jeff uses himself.
I'll ask about the masts that Ron makes now, and the
one he used at the Worlds, but he may be reluctant to
publish the stiffness numbers for all to see (including
competitors). Ron has been continually refining his
masts, and I think he builds the most competive masts
available right now, so it seems unreasonable to expect
him to give away ALL his hard-earned speed secrets.
After all, making and selling DN hardware is what keeps
dinner on the table for his wife and three kids.

658

Posted by: Jeff Kent / Composite Solutions on March 19, 2002 at 00:07:00:

I have decided to publish some of my mast defection data so anyone who is interested or want to compare , can.
The method I measure mast is different than some others. I have measured 300 to 400 spars this way and have collected quite a database to pull from. The data I am showing is for about 37 spars over a decade so you can see how they have changed. The method I use is a simple supported style with 100 LBS located @96" from base. All measurements are in mm and while the stations are at 12" though.. I do not bend the tips as well as the overall span of the mast separate. . From this data I easily determine the ratios of the top mast panel v/s the lower panel as well as being able to create a normalized data table so as to compare actual curves the mast produced without being distracted by the raw deflection data amounts which can be quite deceiving. This process helps when comparing bends to fit particular sail's luff curves.
This information is just the beginning of evaluating masts characteristics. Please find the table as an Adobe pdf format on my website. From there you can download the Adobe reader program for free.. Address is www.csi-composites.com the spars listed near the bottom of table are the most recent

Good reading.

Now show me yours!

Jeff Kent 3535
Composite Solutions Inc.

Tuning Mast Bend

2028

Posted by: Bob Gray on February 09, 2003 at 15:06:44:

It is my understanding that there are two primary causes of mast bend. They are sheet tension, which mechanically bends the mast and the stays, which bend the mast through the force of the wind. It is actually the angle between the stays and the mast that causes the bend and the smaller the angle the more the mast will bend. The side stays effect mast bend much less then the head stay since they are at angles about twice that of the head stay. Some sailors have fixed length side stays, but just about everybody can adjust their head stay. Head stay to mast angle is changed by moving the mast step or changing the head stay angle or both.

Mast bend isn’t the only thing effecting boat performance but it is a major factor. I hear guys saying “If you want to go fast, put your mast step where mine is and yada yada yada.” Well that just won’t work. The limit for the mast step is between 35” and 41’’ behind the center of the steering chock. Most of us use the Sarnes mast step adjustment plate which allows for only 4.5”of adjustment. Is the plate favoring the front or the back of the range? The head stay attaches to the front of the hull and that can vary from 3” to 7” in front of the steering chock. In other words the same placement of the mast step on the Sarnes plate can vary by as much as 5.5”. That will cause a significant difference in head stay angle and rake. What we can do is duplicate the head stay angle and rake by changing the head stay length and mast step position. It is my belief that if the head stay angle and rake are the same for two boats and the other factors such as sailor weight, mast type, sail etc., are equal, then the boats performance should be similar.

Earlier this season I measured the head stay angles on several fast boats. I found this by measuring the distance between the perpendicular to the head stay and the center of the mast step ball. These boats all had fiberglass or carbon fiber masts and they all measured around 33”. 33” equals 15 degrees and each inch either way is one half degree. The rake angle, which was measured by a swing protractor, on these boats varied between 69 degrees and 71 degrees. It would be very interesting to measure the head stay angle and rake on some of the faster boats at a major regatta such as the up coming Centrals. The wind and ice conditions would also have to be noted. This information could be tabulated and made available to the membership. I feel it could really help the average sailor in initially setting up his or her boat.

2033

Posted by: Ken Smith on February 11, 2003 at 10:11:24:

In Reply to: MAST BEND posted by Bob Gray on February 09, 2003 at 15:06:44:

This is in reply to a nice post. But the perfect mast bend is personal. Each mast is slightly different in stiffness, and some are slightly different port and starboard. I have found that the perfect mast bend occurs when the boat is set up so puffs and acceleration (prior to poping out the mast) can make the boat just begin to hike. (In light air, mast power is maximized but so the mast can still be made to bend when sheeted tight). A little more mast rake, and the boat sails fine, feels great and is a little slower than it could be. The mast bends before maximum power occurs. This "optimum rig power" is elusive and small changes in wind, ice make important small adjustments in forestay and side stays. Tuning with a friend shows how important small changes can be.

There are many schools of thought about how to optimize the power in the rig. (but not much variation on what optimum power is). The trick is to get a handle on all the variables. Most do this by eliminating some from their personal consideration. Paul Goodwin (and Ron Sherry) generaly adhere to the side shourds are constant length, then adjust plank position, mast step and forestay tension to get optimum power. Others hold constant the mast step position and adjust side shroud length and forestay tension to optimize rig power. Others hold plank position constant. Several of our German competitors hold constant rake angle, measured with a angle finder, and adjust mast step location, shroud and forestay tension to optimize power. The common thread is what "optimized power" means. Recomendation for learning: On a given day, pick a plank position and mast step position. Then play with forestay and side shroud lengths to optimize.

Now, a boat begins to hike when the upsetting moment (side force times height of effective sail force, perpendicular to the line from the front to the lee runner)equals the righting moment (combined boat and skipper weight acting at the center of gravity times the distance from the CG to the runner line described above).

What this means, simplified, is that a heavier skipper can have a more powerful rig. A more powerful rig is a stiffer mast, or a softer mast set with less rake, or a softer mast set more aft, or a stiffer mast set more upright and forward, or ...

Rig power increases if the mast is raked less, if the mast step is moved aft, if the shrouds are tighter, if the plank is moved forward. Rig power is reduced if the mast is raked more, the shrouds are looser, if the mast step is moved forward and if the plank is moved aft. Obviously, changing one thing in a "more power" direction can be countered by changing another in to a "less power" position.

One additional hint. The more tension you can cary in the side shrouds, the better the boat seems to point. As you play the tuning game, "optimum power" can be achieved several ways, and if you like to point, the way that gives you more side shroud tension may help you point. Sometimes footing is faster, however.

In the last Gold fleet race at this year's Gold cup race, the winds were 5 mph at the start and shortly dropped to 2 mph after the start. The time limit requires the boats to be sailed about 14 mph in order to finish on time. Ron finished 15 seconds under the time limit, which means he maintained a boat speed at an average of 7 times the wind speed for the whole race. That is done by footing not pointing, in those conditions.

GOOD LUCK!

Selecting a material

471

Posted by: Paul Goodwin on January 10, 2000 at 08:38:46:

In Reply to: NEW TOPIC:Replacing the carbon fiber tape on mast? posted by Charles Paquette on January 08, 2000 at 10:32:13:

There are substitutes for carbon fiber tape which *may* work, but
I guess it begs the question "why".

Carbon fiber has some unique properties which lend it to applications
such as a mast. It has excellent compressive strength, and is easy
to apply using home shop techniques. The cost is not prohibitive
in the small amounts usually used on a mast.

If I was going to use something to replace carbon fiber, I would use
a unidirectional fiberglass tape, but it's not always as easy to find
as carbon fiber.

389

Posted by: Geoff Sobering on January 06, 2004 at 11:58:02:

In Reply to: What type mast is preferred? posted by John on January 05, 2004 at 17:50:25:

Summary: "Bendy is best" (IMHO)

Having run through almost the gamut of possible masts in the past few years (solid-wood "tree-trunk", Aluminum (twice), very-bendy glass (twice), and stiffer glass), I can state that my personal opinion is that the DN is almost a different boat with a bendy mast.

With a stiff mast, the boat tends to hike pretty easily. This means that a substantial portion of your attention has to be applied to keeping the runners on the ice. With a bendy mast, the boat is much more "self tending", and you can pay much more attention to your surroundings, tatics, sail-trim, etc. I personally think it's much safer to be sailing in a boat with a bendy mast, because you can devote much more time to keeping up with what's going on around you.

What kind of bendy mast you get depends more on cost, longevity, etc. For example, the three composite masts I've sailed all shared the same desirable bendiness, but using vastly different technologies: one was a built in two halves and glued together, one was filament-wound, and one was built in a male/female mold. All of them (even the two-parter built in 1993) have withstood racing in 20+kn winds (and, as a member of the "100-kilo club", that's saying something!).

The commercial masts (Ron Sherry and Jeff Kent) appear to have a nearly perfect reliability record. Many (most?) of the composite masts built by others also seem to be holding up pretty well. The good news is that there are now more and more older composite (and wood/carbon) masts coming on the used market at quite attractive prices.

390

Posted by: John on January 07, 2004 at 12:52:08:

In Reply to: Re: What type mast is preferred? posted by Geoff Sobering on January 06, 2004 at 11:58:02:

All right....I think I understand.

I gather that wood is bendy. It is also perhaps more traditional and preferred by the show people? But what about life expentancy....is it good for racing???

Aluminum I gather is stiff. Good for accelleration but less forgiving in gusty conditions???

Carbon I gather is the best for racing. Long life expectancy, and it can be made bendy or stiff depending on the boater's preference??

I think I got it. Thanks so much. If you know anyone with a boat for sale check the "Michigan resident needs DN" thread above.

Best-John

392

Posted by: Geoff Sobering on January 07, 2004 at 22:26:23:

In Reply to: Re: What type mast is preferred? posted by John on January 07, 2004 at 12:52:08:

> I gather that wood is bendy. It is also perhaps more
> traditional and preferred by the show people? But what
> about life expentancy....is it good for racing???

Wood can be made stiff or bendy. But, as they say, "they go fastest just before they break". There are quite a few wood/glass/carbon masts out there that seem to be less fragile when bent quite a bit.

I'm curious now, can someone with more experience talk a bit about the current status of wood/glass/carbon masts? Is it a viable method for constructing a competative mast? I remember some discussion last winter about possibly publishing a design and lamination schedule for building a robust and flexible mast. Has anything come of that? I seem to remember the consensus was that the commercial masts probably have the best cost/benefit ratio and that it was better to just buy one and concentrate one's building/tuning efforts on runners.

> Aluminum I gather is stiff. Good for accelleration but less
> forgiving in gusty conditions???

Aluminum is stiff. I don't think anyone currently thinks it's optimum for any conditions.

> Carbon I gather is the best for racing. Long life expectancy,
> and it can be made bendy or stiff depending on the boater's
> preference??

Pretty much. Although Glass seems to work just as well, the masts are just a bit heavier (but not much).

Another question for the experts out there: is there any (big) advantage of a mostly Carbon mast over a mostly glass one?

Good luck in your search for a boat. It's a great way to spend the winter months. Depending on your aspirations, I wouldn't worry too much about your first mast. Obviously, if you're planning to become competative as quickly as possible you'll want a better mast earlier (along with runners, plank, etc.). On the other hand, you can sail resonably fast with an stiff mast and plate runners. For example, at the Western Regattta last weekend a friend of mine beat three boats in the Silver fleet on Saturday sailing with a Kenyon Alumiunm mast and plate runners. That was in "big wind", when the stiff mast should have been at the biggest disadvantage.

Cheers,

Geoff S.

394

Posted by: Ken Smith on January 07, 2004 at 23:04:39:

In Reply to: Re: What type mast is preferred? posted by John on January 07, 2004 at 12:52:08:

John:

Preferred for what? Any mast makes the boat go fast and is fun. Being "fastest" means sailing well. Bendy masts are easier. To almost quote Jane Pagel: "If we hadn't gone to bendy composite masts, there is no way I could be out here sailing at the age of 70."

The top racers are all using composite masts: Glass, or glass and carbon fiber. All the top US sailors I know of are using either Sherry masts (Composite Concepts) or Kent (Composite Solutions) masts. The entire Detroit crowd is using Sherry masts. They are all fast. In addition to these, European sailors are using Ake Luks masts, Darius Polzen masts and perhaps a few others. Borg Bohn (last I heard) prefers wood and composite masts, but he is a rare guy.

The composite masts bend and are durable (though not indestructible). They are also more expensive on first purchase. They are available used. They are the best buy if you want to race. Old bendy wood-glass-carbon masts are cheap if they can be found used. They can be built but are tough to make fast without a lot of learning. If over bent, they WILL break. To sail a stiff wood or aluminum mast fast, there is lots of work involved.

Cheapest is old stiff wood masts, and home-made composite masts that someone moved away from. Some of the home-made composite masts are very good, but they have no pedigree, so they are cheap. Bob Rast, Paul Schutte and others have turned out some very good masts. Caveat emptor.

395

Posted by: Bob Rast on January 08, 2004 at 07:10:05:

In Reply to: Re: What type mast is preferred? posted by Geoff Sobering on January 07, 2004 at 22:26:23:

Most composite masts are about 70 to 80 percnt glass. I have built several with carbon fiber. Our masts have about 7 to 8 layers of glass total, By using cabon fiber instead of glass you eliminate weight. The Glass masts we built started out around 18 to 20 lbs, The first mast I built substituting 2 layers of carbon for glass weighed 14 lbs which was under class spec of 15 lbs and had to add lead to mast to be legal, The carbon seems to make mast a little snappier? but this is hard to measure, A all carbon mast would probably weigh under 10 lbs and the cost would be heigher for materials,.and add 5 lbs of lead to make it balance and class legal,Carbon fiber really only makes the mast lighter and cooler looking costs more and there are plenty of guys sailing older glass only masts going fast,

Fiberglass construction

514

Posted by: Paul Goodwin on November 27, 2000 at 14:04:36:

In Reply to: fiberglass mast construction posted by Wayne Matheson on November 26, 2000 at 22:12:29:

Wayne,

I've used short fiberglass tubes very successfully (and they are
also used on at least one "production" mast). I use a tube of 1/2"
OD, 3/8" ID, and 5' long. Three individual lengths are connected
together with some thin (4 oz or less) glass cloth. This joint
doesn't need to be as strong as the tube, it just needs to hold
together long enought to get it into the mold, and it keeps epoxy
from getting inside the tube during layup.

It is best to use a "one-piece" layup, meaning that the mast is
not made up of fore and aft (or side by side) pieces. This can
be accomplished in different ways. Ron Sherry uses a female mold,
and puts a pressure bag inside the mast to force the material out
against the mold. I believe Jeff Kent uses a male mold and uses
an autoclave to condense the layup during curing.

There are benefits to both methods, and neither is outside the
abilities of the home builder. The female mold may be easier to
construct, since a mast can be used as a plug for the majority of
the mold.

You'll have difficulty getting a layup schedule from either Ron
or Jeff, since they have both invested quite a bit of time and
money in getting it right. I can't really give much guidance on
layup schedule myself since I helped Ron develop his mast.

The Gougeon Brothers have some information available on vacumm
bagging, and a good technical library is likely to have some
serious publications directed towards production of composites.
While this production oriented info can be daunting, there are
a lot of good ideas the can be applied to home building.

515

Posted by: Jeff Kent CSI on November 28, 2000 at 23:23:33:

In Reply to: fiberglass mast construction posted by Wayne Matheson on November 26, 2000 at 22:12:29:

Wayne,
Paul is generally correct. there are some mast that are made in halves out there but they arebocming fewer and fewer.
the Masts that I produce are made over a custim alouminum mandrel to which I apply the materials to the outer surface. the materials are in the form of prepreg type. If your not familiar with these ,dont feel left out I use them almost totally in my composite bussines. they produce very repeatable laminates due to the high control of the fibers and resin content. plus the resin has better mechanical properies as well. the inner most layers are carbon 300gsm uni directional tape place at 90 degress to the mast,in the hoop direction. these can be as many as 3 plies , these help produce section shape stability. very important when bending out of columb.after that I apply two layers od carbon laid at plus and minus 45degress. At that point i apply the same pultrude fiberglass tubing paul mentioned. now i apply all of the rest of marteials that are E glass uni fibers the majority aprx 80% are in the zero degree axis (along the lenttgh of the mast.coupled with the balence in 45s and 90s

If you notice i use all the higher stiffness materials on inner surface of mast where stresses areless and on the outside I use the glass whisnot as stiff and contains a much higher elongation to failure number than carbon.
I fine tune the mast bend wit varying tapering of glass unis to fit the predicted curves from an excel spreadsheet that i ahve deveolped overa decade. factoring in all changes of laminate thickness materialtype , oreintation and location on mast the spread sheet can predict deflection well within 2-3%error.

I fyou need any help or materials for your own project such as baginng peel plys carbon dry or prepreg same with glass please contact me.
I also offer my regular mast in kit form ( all you haveto do is attached all suppiled hardware) for $800 usd for oniece mast or 900 for the two piece veirson

good luck making your own . it can be a fun and rewarding project

jeff kent
Composite Solutions Inc
781-335-4650
csi-composites.com

Mast minimum weight

516

Posted by: Bob Rast DN1313 on November 29, 2000 at 14:06:26:

In Reply to: Re: fiberglass mast construction posted by Jeff Kent CSI on November 28, 2000 at 23:23:33:

I built a mast last year blow molded like sherry masts and used several layera of carbon in place of the e - glass we normaly use.
It came out with the deflection that I wanted and was lighter in weight than the all fiberglass masts. Weight with hardware was aproximately 14 lbs under the minimum weight of 15 lbs . My question to you is do you think that the minimum weight spec and balance rule are
still needed since the rules changed the material require ments allowing all glass or carbon masts. I m sure that if you were to build a mast out of 100 % carbon you would probably havve a finished product weighing under 10 lbs. Balancing is another question. I hate the the thought of having to add ballast to a mast. Any Ideas?

517

Posted by: Paul Goodwin - Tech Committee Chairman on November 29, 2000 at 16:25:09:

In Reply to: Re: fiberglass mast construction& Min Weight spec posted by Bob Rast DN1313 on November 29, 2000 at 14:06:26:

This is an easy one to answer. The minimum weight and balance point
specs were written for masts just like yours.

The purpose of these specs is to temper the drive towards more and
more exotic construction. The same is true of the minimum weight
requirement on planks. This way, reduced weight is taken out of the
equation when deciding on what construction method and materials will
be used. It is hoped this will help keep the costs down, and
balance the performance among the different designs.

522

Posted by: Paul Goodwin on December 12, 2000 at 21:30:55:

In Reply to: Re: fiberglass mast construction& Min Weight spec posted by Bob Rast Dn 1313 on November 29, 2000 at 18:02:22:

To answer Bob's questions most directly: wrong; wrong; sort of;
true; yes; yes; yes.

Here's a longer version. The weight and balance specs were introduced
in 1966 along with the fiberglass/carbon fiber composite mast. It is
clear that using higher modulus materials allows less material to be
used, yielding reduced weight. This can also lead to exotic/expensive
masts if there is a desire for the lowest weight possible.

The weight and balance point were established to minimize the
performance differences between aluminum, wood, and composite masts.
It was hoped this would allow relatively low cost building methods to
yield state of the art masts. So far it has worked.

528

Posted by: Paul Goodwin on December 19, 2000 at 21:20:21:

In Reply to: Re: fiberglass mast construction& Min Weight spec posted by Paul Goodwin on December 12, 2000 at 21:30:55:

My last post about the mast weight pecification was in error, I'm suprised somebody didn't catch me.

The weight and balance point specs were introduced in 1988 along with the restriction on wood mast construction (controlling the wood thickness in the wall, and glue joint width). When the mast spec was changed to allow composite construction (no wood required) in 1996, the weight and balance point specs were left in place.

But the resoning has remained the same. The purpose of these specs is to help reduce the desire to build exotic masts.

515

Posted by: Bob Rast DN1313 on December 20, 2000 at 13:27:19:

In Reply to: Re: fiberglass mast construction& Min Weight spec - a correction. posted by Paul Goodwin on December 19, 2000 at 21:20:21:

My main point about discussion of these specs are as you have stated. The balance spec really does not have any application to composite mast unless you want them to balance for some reason. a thiner softer tipped composite mast will be just as strong even if it doesnt balance per the old spec.I think that we might look at eliminating this specification entirely for it is really of no use.Concerning the minimum weight specification , and use of exotic materials , and increasing costs , As a home builder , I don,t feel that carbon fiber is Exotic material as it is already used in masts and runners. The cost of using it in mast construction is a consideration but if I build my own masts using carbon,I can still produce a mast for much less than a commercialy available product.There fore i dont feel that the cost issue is relavent unless you are concered about the cost of a commercialy available all carbon mast from one of 2 or 3 manufacturers.In keeping with the class philosphy of keepin the Dn as a home buildable class, There are a number of sailors building thier own masts at this time and anyone who has ever built a wooden mast can easily build a mold and produce thier own at much less than the going Retail prices.Carbon Fiber is not Exotic or costly in home built products and is readily available form a number of sources .I think that the Minimun weight spec could be relaxed to say 10 or 12 lbs and not Drive up the cost of masts dramaticaly also there are many sailors with 2 or 3 fiberglass masts already so aparrently cost isn't a big issue.

534

Posted by: Bill Condon on December 22, 2000 at 12:52:41:

In Reply to: Re: fiberglass mast construction& Min Weight spec - a correction. posted by Bob Rast DN1313 on December 20, 2000 at 13:27:19:

Bob: The problem of cost is still a major factor. Although carbon is not an exotic fiber there are many different grades of carbon available and many of the aerospace fabrics are outrageously expensive. There are also some other materials that would be considered exotic , with a high cost associated with them. Min. weights and balance points help keep things in check for the home builder and keep the materials within their scope.

530

Posted by: Paul Goodwin on December 20, 2000 at 16:45:02:

In Reply to: Re: fiberglass mast construction& Min Weight spec - a correction. posted by Bob Rast DN1313 on December 20, 2000 at 13:27:19:

We could probably go back and forth on this all year. Hey! Maybe
that's not a bad idea! Actually, I find myself defending specs and
interpretations that I don't even believe in only because I am
familiar with the arguments, and nobody else seems to step forward
sometimes.

You make a good point about carbon fiber being used in masts and
runners. It is interesting to note that Jeff Kent's masts don't have
any carbon fiber in them this year. As far as runners are concerned,
the carbon stiffeners are a significant portion of the total cost, and
the cost of commercially available runners has been getting quite high
(like $600 EACH for 440C insterts). In my runners, the cost of the
carbon stiffeners was about the same as the raw steel (440C). This is
because the stiffeners were laid up using a good grade of prepreg
carbon.

As far as carbon prices go, there are very exotic and expensive
materials available to the commercial builder. These carbon fibers are
aerospace materials with specialized properties (such as high specific
stiffness). You will not see the prices of these materials because
they are not available to the home builder.

I understand what you are saying about the cost of home building.
However, the specs can't limit materials for commercial builders and
allow them for homebuilders. And unfortunately many of the sailors in
our "home buildable" class no longer build anything. So, the weight
spec helps to address the problem of commercially available composite
parts getting more expensive over time.

Besides, you are not restricted any more than the commercial builders.
I think you'll find that if you build a fiberglass mast (no carbon) it
will come out very close (and usually over) the minimum mast weight
and balance point. So why use carbon? ->To get the weight lower. If
there is a minimum weight, and using carbon means you have to add
ballast, then you're less likely to use carbon. Less carbon = a
cheaper mast. At least that's the theory behind minimum weight
specs...

532

Posted by: MIKE OBRIEN on December 21, 2000 at 13:31:50:

In Reply to: Re: fiberglass mast construction& Min Weight spec - a correction. posted by Paul Goodwin on December 20, 2000 at 16:45:02:

Paul,

I which I was able to take the time to comment on
the items you reply to on the DN site. However aside
from present time constraints you are more knowledgable
then most of us. You contribution is very good for the
class, for the beginners and seasoned sailors alike!

In this case you are commenting on one of the best
specifications the DN Class has. A Minimum weight and
balance point helps us keep a focus cost, time required
to build and design. It is something that should be
considered when interpitating and or writing new
specifations as it is tangable and enforcable.

Thanks

Mike DN US 3456

533

Posted by: jeff Kent on December 21, 2000 at 20:35:10:

In Reply to: Re: fiberglass mast construction& Min Weight spec - a correction. posted by MIKE OBRIEN on December 21, 2000 at 13:31:50:

Paul,
Please check back in a reply in November that I generally outlined the construction process and materials used in my spars,
I do use Carbon, but only in off axis fibers 90's and 45's As I stated it is the best material to use to maintain "hoop" stiffness or section stability. The rest of the fibers, the o’s are e glass in order to get strength, elongation and minimal stiffness.

Best regards to you and all for the holidays

Jeff Kent

Luff tube

613

Posted by: rob on February 03, 2002 at 17:41:00:

what is a good material to use for the luff tube. where can you get purchase the materials if availible. thanks

614

Posted by: Bob Rast on February 04, 2002 at 09:56:18:

In Reply to: luff tube posted by rob on February 03, 2002 at 17:41:00:

What type of mast are you building , wood or fiberglass? Carbon tubes are the best as they bond well and add some stiffness to the mast.Try Tom Meyer 612-474-3916 for the carbon tubes. I have used 1/2" pvc in fiberglass masts and wood booms.. If you use pvc sand well with corse sand paper so it bonds well and add some reinforcement over area where the boom hits the mast so you dont crack it, I add some carbon cloth over this area. Aluminum tube works also but shrinks in cold temps and will make mast curve back a little.

615

Posted by: Geoff Sobering on February 04, 2002 at 13:19:29:

In Reply to: Re: luff tube posted by Bob Rast on February 04, 2002 at 09:56:18:

I've had good experience with CPVC conduit (thinner wall and smaller diameter than regular PVC pipe) on both a boom and glass mast. One nice characteristic of the PVC is that it is intrinsically slippery.

Bob's advice on taking care with bonding is crucial. In addition to bonding the tube to the mast, I laid a layer (or two) of 6 oz. glass fabric around the boom and over the tube. I used microballons to fair any hollows between the tube and boom. After the epoxy set, I routed out the slot, then sanded all the edges smooth. It worked really great. The mast in question is a number of years old (5-6+) and shows no signs of any separation of the tube from the mast.

Cheers,

Geoff Sobering
US 5156

616

Posted by: Paul Goodwin on February 05, 2002 at 10:50:08:

In Reply to: luff tube posted by rob on February 03, 2002 at 17:41:00:

I have used a few different tubes over the years, and settled
on one type for masts -- fiberglass tubing.

Sure, you can use carbon fiber tubing, though I'm not sure
why it would be desirable (more fore and aft stiffness can
sometimes be a detriment). If you need more fore and aft
stiffness, there are cheaper ways of doing it. Actually,
the tubes Tom Meyers sells are black, but I think they are
fiberglass, not carbon (I could be wrong about this, I've
been wrong once before).

I wouldn't use pvc tubing for two reasons, it doesn't bond
very well, and it has a thick wall.

Aluminum tubing has fallen into disfavor because it also
has poor bonding characteristics (worse than pvc), and it
has the thermal problems (mast bend with temperature change).

You can get fiberglass tubing from McMaster Carr (or other
industrial supplier) or from Tom Meyers. If you're in the
Detroit area you can save some time and effort by calling
Ron Sherry (Composite Concepts) and ordering from him.
The fiberglass tubing Ron Sherry is using is 0.505"OD and
has a .050" wall thickness.

Ron's tubing is about 5 feet long, so you need 3 pieces for
a mast. To join the 3 pieces you can use Ron's secret trick:
1) Lay the ends of the tubing in a v-block of some sort.
2) Cut a small patch of 1/2oz glass cloth (you can find
this at a model shop).
3) Wrap the cloth around the joint, it should overlap so
it's a couple of layers thick.
4) Saturate the cloth with instant glue (cyanoacrylate - also
from the model shop).
5) Spritz (that means "spray lightly") with "Zip Kick".
This is an instant hardener for super glue (also get some
of this while you're at the model shop).

The instant glue will harden immediately, creating a weak
but adequate joint. The purpose is not to form a structural
joint, but to keep epoxy out of the tube when you make the mast.

618

Posted by: Geoff Sobering on February 05, 2002 at 16:14:25:

In Reply to: Re: luff tube posted by Paul Goodwin on February 05, 2002 at 10:50:08:

One comment on the black fiberglass tubes (in the "don't do as I did" category). The 5 foot length of the tube means it's possible (likely?) to place a joint between tubes near the critical mid-point between the mast-base and the hounds. Theoretically, this can cause a stress-concentration point.

I don't know if it's just coincidence, but a mast I helped build (with the black glass tubing) failed _right_ at a joint in the luff-tube. Granted, this was a *very* flexible mast, and probably would have broken anyway under the circumstances, but it was an interesting observation.

Cheers,

Geoff Sobering
US 5156

620

Posted by: Paul Goodwin on February 06, 2002 at 07:51:26:

In Reply to: Re: luff tube posted by Geoff Sobering on February 05, 2002 at 16:14:25:

I believe the failure at the joint in the tube was just a
coincidence. Ron has built a lot of masts (400+) using
these tubes and there has been no indication of a problem.

The joint would only cause a stress concentration if there
was a significant change in stiffness at the joint. The tubes
are very compliant relative to the mast, so the stress
concentration should be negligible. Additionally, the back
of the mast is mostly in compression when the mast bends,
so the joint has even less effect.

764

Posted by: Paul Goodwin on January 16, 2003 at 14:06:29:

In Reply to: fiberglass luff tubes posted by Rob L on January 16, 2003 at 13:16:49:

I get my tubes from Ron Sherry at Composite Concepts. They come
in 5 ft sections, so you need 3 of them for a mast. Ron glues the
sections together with a little 3 or 4 oz glass cloth and super
glue, kicking it off with "zip kick". The joint between the tubes
doesn't need to be strong, it just has to keep epoxy out of the
tube when you glue it in.

The best way to bond it to the mast is with epoxy. It sounds like
you are planning on putting it in an old mast. A little more info
on the project would help. Generally, you route a 1/2" diameter
groove using a core box bit, then glue the tube in with thickened
epoxy. A pretty simple project overall. If you are building a
new wood mast, then you glue it in when you glue the two halves
together.

Once the epoxy hardens, you need to cut a slot for a luff groove.
Ron uses a "Skilsaw" with carbide tipped blade and a home made
jig to guide it down the tube. I have had really good luck using
a solid carbide router bit (1/8" straight burr) and a guide
attached to my router. Either way, you'll need to sand the
slot afterwards to remove slivers and smooth the edges.

Alternative materials for luff tubes

765

Posted by: BobRast Dn1313 on January 17, 2003 at 11:55:00:

In Reply to: fiberglass luff tubes posted by Rob L on January 16, 2003 at 13:16:49:

As a alternative to fiberglass, I have used 1/2 PVC tubing available in local hardware store. I have used it in Fiberglass and wood masts and booms without any failures.The inside diameter is larger than the fiberglass tube and the sail goes up real easy. To bond with epoxy, ruff up surface with some course sand paper and wet out with epoxy. . I butt sections together and tape with packaging tape to keep out glue in fiberglass masts. If blow molding fiberglass mast dont forget to tape up ends to keep glue out of tubes.I dont know if a carbide blade would be best for cutting the slot in pvc. I use a composition blade which is for cutting metal or masonry about 1/8 in thickness.My wife loves it when I do this in the basement.I usualy wait until she goes out and have some one follow in front of the cut with my shop vac to keep dust down to a minimum. The only disadvantage would be less stiffness than fiberglass tubes and that could be fixed by adding some carbon to the front or sides or back of the finnished mast. Also it is advisable to add some extra cloth or carbon on tunnel where your boom hits so you dont crack the pvc tube. Cheap, 1.99 for 10' section.

766

Posted by: GeoffS on January 17, 2003 at 14:02:27:

In Reply to: alternate to fiberglass luff tubes posted by BobRast Dn1313 on January 17, 2003 at 11:55:00:

I just want to mention some sucesses I've also had with CPVC tubing.

The most dramatic example is a glass mast from the early experimental period (ca. 1993) that was built with a CPVC luff tube. I'm pretty sure it was sailed quite a bit before I was borrowed it in 2000, and I sailed it pretty hard for a season or so without any major problems. The only repair I remember doing was to smooth out the sail entry channel because it was cut a bit high on the mast, and my boom rode over it as I sheeted in and out.

I also replaced the boltrope channel in an older wood boom with CPVC. I basically followed the procedure Bob suggested. I routed out a half-round channel. Then I sanded with sandpaper wrapped around a 6" long section of CPVC (I think my router bit was a bit too small). After roughing up the tube with 80-grit sandpaper, I bonded the tube in place with epoxy and overwrapped the top 1/2 of the boom with 6 oz. glass. After everything set, I cut the slot in the tube and glass with a 3/16" router bit. If I remember correctly, I was a bit paranoid about the tube pulling free at the clew, so I would tie my sail's clew-grommet to the boom with a short length of vectran; it slid smoothly enought along the boom that my outhaul adjuster worked fine. However, I never saw any indication of separation of the tube and boom.

I'm not smart enough to remember to seal joints and ends, but I did wax the interior of the tubing with some mold-release wax, so any dribs of epoxy popped right out.

One other advantage of CPVC is that it's a slippery material, so bolt-ropes slide up it pretty eaisly (the oversize ID tha Bob mentions also helps).

If I were to use CPVC again, I would probably flame-treat the surface to help with adhesion (as described in the EpoxyWorks #16, Fall 2000).
http://westsystem.com/ewmag/16/glueinglumber.html

Cheers,

772

Posted by: David Wilkins on January 20, 2003 at 10:06:27:

In Reply to: alternate to fiberglass luff tubes posted by BobRast Dn1313 on January 17, 2003 at 11:55:00:

I too have used 5/8" od pvc tube for wooden boom bolt ropes. I've been pretty quiet about it (till now) because I don't believe it is an allowable material. It should be however at 2$ for 10'. The high performance to low cost/availability ratio here is one of the best examples of true home buildable DNing.
After sanding pvc well and rough, wash the surface with acetone before glueing.

David Wilkins

775

Posted by: mark kiefer on January 20, 2003 at 20:57:18:

In Reply to: Re: alternate to fiberglass luff tubes posted by Geoff S. on January 20, 2003 at 14:14:12:

I've seen enough pvc tubes in spars to personally conclude it's a well accepted means of constructing a wood spar (mast or boom). Much like bolts or threaded rod in T & Angle runners, people have always used the materials,... of course the committees (protest & technical) may have another opinion. :)

Additionally, it's sure not as thermally wild as aluminum tubes.

Considering the nominal additional cost, smaller outside diameter, and superior bonding performance of fiberglass tubes, it's my choice hands down.

Cutting a slot

464

Posted by: Jim Olsen on January 04, 2000 at 18:56:06:

In a month or two I will need to cut a slot in carbon fiber luff tubes. I made a jig to go on my table saw. It works fine. However, when I cut slots in tubes last summer the electrical switch in my saw went out 10 days later,(the motor gave out two months later). I heard somewhere that carbon dust messes up electrical stuff. Is this true, and is cutting more slots likely to mess up my saw again, or is this an old wives tale?

468

Posted by: Jon Hougaboom on January 07, 2000 at 14:12:17:

In Reply to: NEW TOPIC: Slotting Carbon Fiber Luff Tubes posted by Jim Olsen on January 04, 2000 at 18:56:06:

Carbon Fibers are very good conductors of electric current.

Yes they can and will short out electric motors. A good way of preventing your motors from shorting out is to cover your air intake's with the same material that your furnace filters use. This will stop the fibers that are released while cutting the tube from getting sucked into the electric motor.

Other Wood Masts

633

Posted by: tom austin on February 22, 2002 at 14:38:06:

In Reply to: How to modify a wood DN mast? posted by Bruce Lowstuter DN4580 on February 22, 2002 at 10:49:50:

I have a veneer mast that was originally made by Joe Norton over ten years ago. The mast thickness walls were 5/16" thick. I used a router to remove slots 3/16" deep for about 8 feet starting 2.5 feet from the base. I then chiseled out the remaining "Ribs" being carful not to perforate the floor of the channel. The slot ended up being 2 & 3/4" wide. I filled up the slot with heavy unidirectional cloth. After curing I checked the stiffness and found that the mast stiffness was greater so I sanded a layer or two off. My goal was 1&3/4" side deflection with a hundred pounds when the mast was supported at the base and hound. I believe you could use fiberglass tape and do less sanding after your done. The mast now preforms very well and is lighter than most glass masts.

634

Posted by: mark kiefer on February 22, 2002 at 20:26:14:

In Reply to: How to modify a wood DN mast? posted by Bruce Lowstuter DN4580 on February 22, 2002 at 10:49:50:

Comments to Bruce’s post are inserted below:

Posted by: Bruce Lowstuter DN4580 on February 22, 2002 at 10:49:50:

Does anyone have any advice on how to modify an wood strip mast to make it competitive with the new fiberglass/carbon fiber composite masts?

[Mark Kiefer] Everybody in the fleet has advice, some is good, your milage may vary.

When I first started iceboating 13 yrs ago, I bought an aluminum Norton wing mast. Three years later, I built a wood mast using 1/4" ash strips.

I would like to modify the strip mast to make it more flexible. Someone suggested routing out an 8 foot section below the hounds and adding fiberglass. Does this sound like a good idea?

[Mark Kiefer] Dave Kickhafer suggested this, he's one of the best tinkerers in the fleet, sails with a 100 % homebuilt program, he REGULARLY sails in the front half of the Gold Fleet, and knows his stuff.

Has anybody else done this? Sounds like a good idea - if it will work. I don't want to destroy a good mast, but it sure would be nice to be able to modify this mast.

Is a 3" fiberglass cloth tape ok for this, or do I need uni-directional fibers?

How wide a slot and where to cut? Side walls only or nose also?

How thick should the fiberglass section(s) be?

[Mark Kiefer] Ask Dave, or better, Dave help out here

Any advice would be appreciated. I'm too cheap (or too stubborn) to buy another mast and I don't want to lay up 3 or 4 fiberglass masts at $300 a pop, before I figure out the layup schedule.

[Mark Kiefer] The game at the end of the day (ateod) is the RELENTLESS pursuit of speed. It's a continual process. And Frugality is a virtue. :)

How to modify (tune) a wood mast

636

Posted by: Jay Spalding on February 25, 2002 at 10:02:52:

In Reply to: How to modify a wood DN mast? posted by Bruce Lowstuter DN4580 on February 22, 2002 at 10:49:50:

In the bad old days the wood had to be 2" wide. This is what made the mast unreliable if soft enough and too stiff if strong enough. It no longer does. I and several others have had good luck by using a saber saw (short blade)and cutting a slot in the front of the mast between the hound and the base, Clamp it back together and cut another one, etc until you get the mast down to 2" overall width. You can usually get away with 2 cuts before you need to do anything with the aft part of the mast. Depending on the room in your boltrope groove you can make a cut here too. It is is perfect fit even if the line isn't perfectly straight. You just glue it back together. This is an evening type project. You can similarly taper the mast by cutting a vee out of the top part.

637

Posted by: Jane on February 25, 2002 at 16:52:15:

In Reply to: Re: How to modify a wood DN mast? posted by Jay Spalding on February 25, 2002 at 10:02:52:

Don't overlook the fact the minimum thickness for the mast is still 2 inches below the hound. The percentage of wood may be decreased. Be sure to read the specs.

642

Posted by: Bruce Lowstuter DN4580 on March 01, 2002 at 07:32:11:

In Reply to: Re: Mast bending posted by Ken SMith on February 28, 2002 at 07:54:22:

Ken, thanks for your insightful reply. There is a lot of information here to digest.

Has anyone done any bench measurements to quantify the deflection of masts which fall into those three broad categories of soft, moderate and stiff? Using a standardized load (100 lb load, supported at base and hounds) what are the deflection ranges?

For anyone who is interested, I split my strip mast lengthwise into the original 2 halfs and am removing the 7 tows of carbon fiber from the inside. The process is to use a heat gun to soften the epoxy and then the fiberglass and carbon fibers scrape off pretty easily.

I'm thinking of putting one layer of fiberglass on the inside, routing out the sidewalls below the hounds from the outside (leaving a thin layer of wood) and filling in the routed section with fiberglass. This will, hopefully, give a flexible sidewall and a stiff tip section above the hounds.

Strengthening Wood Masts

2103

Posted by: Doug O on September 07, 2003 at 20:58:40:

I have an older DN with a wood mast. It was suggested I wrap the mast in three places with fiberglass to give added strength and help avoid the mast breaking. Any thoughts on this ?

2106

Posted by: Tom Austin on September 09, 2003 at 11:02:51:

In Reply to: Re: Strengthen Mast posted by Doug O on September 08, 2003 at 11:46:31:

If you are new to the DN and the mast looks sound I would just sail it. Masts would tend to break at the base, the hound where the stays attach, or along the bottom section from four to eight feet off the deck. Most people don't start out by trying to go for the optimum preformance that a modern DN can give. If your mast is a 30 or 40 year old solid wood mast then you won't want to use a modern rake. Just set it up so the boom is level to the ice or higher. More recent masts (5 to 15 years old) are designed to bend more using mast rake to promote bending. They will bend alot more before they break than older solid ones.

2102

Posted by: Doug O on September 07, 2003 at 20:58:02:

I have an older DN with a wood mast. It was suggested I wrap the mast in three places with fibrglass to give added strength and help avoid the mast breaking. Any thoughts on this ?

Glass Mast Repair

741

Posted by: Brian Lamb on December 22, 2002 at 19:19:47:

My buddy got a leg up on me this afternoon heading for the windward mark and I guess I sheeted in a little too zealously on my homemade fiberglass mast - on the next windward run I noticed I now have two wrinkles forming on the outer aspect of my mast about 5 feet off the deck spaced about 8 inches apart. At rest, the breaks appear as jagged horizontal cracks about 1"x 1/8" deep. I made this mast three years ago by laying up four layers of 24 oz. mostly unidirectional fiberglass (ends and leftovers bought cheap locally)with West System over a male mold of sculpted 2" blue closed cell foam. I further complicated things by laminating in carbon stringers in what I thought to be key stress areas. The process took three successive layups and on exam it appears I've cracked only the first two layers of fg, down to the 6 oz carbon tape. Remarkably, two masts I made this way have worked and held up well until now and over time I've learned to really like the bending properties of this particular mast - but can it be saved?
I'm thinking what I have to do is sand down the area and rebuild it with more fiberglass - but won't this do some deadly things to the existing unbroken matrix around the break? Would it be possible to just put a graduated patch of fiberglass over the kinked area and hope it doesn't stiffen the mast too much in that crucial area?
Sure, I guess I know the mast is toast, but remarkably I was able to continue sailing it hard for the remainder of this afternoon and it didn't seem to get any worse. If it were yours, how would you tweak it to try and nurse it into the new year and beyond? Thanks for your ideas. - Brian

743

Posted by: Paul Goodwin on December 31, 2002 at 11:59:05:

In Reply to: Has anyone saved a "kissed" (kinked) FG mast? posted by Brian Lamb on December 22, 2002 at 19:19:47:

I haven't fixed one personally, but I can relate the method
recommended by Burt Rutan for repairing composite airplane wings.
If it works for a wing, it should be a good start for repairing
a mast. This should not change the stiffness if it's done right.

You start by carefully sanding the area under repair to create
what would be a scarf if you were working with wood. You sand
through the layers of composite creating an angled edge.
Assuming the layers consist of .010 thick layers (typical for
a 6-8 oz cloth), you want to create an angle that exposes 1 layer
every inch. As you sand, the layers will expose themselves,
looking like the rings on a tree. I would start with aggressive
removal initially, then move to finer grits and more careful
sanding as you approach the final "feathering". This requires
some careful sanding to get it all right.

Since there are a lot of layers in a mast wall, this will
eventually cover a pretty big area. The "scarf" angle can be
more aggressive in the low load direction (toward the front
and trailing edges of the mast). This is a good thing since
there is not enough distance in those directions to get 1 layer
per inch.

Then you complete the repair by adding new layers of glass/carbon
cloth to replace the material you removed. You add the smallest
patches first, squeegy well to remove excess epoxy, and trim each
patch to be the size of the layer you sanded away. You have to
be pretty good to trim the patches without messing up the edges
too bad. Once you've added all the layers, cover the patch with
some "peel-ply" and squeegy again. At this point will have a
complete repair. Some light sanding to smooth things out (but
don't sand through any layers), and coat with epoxy.

This will obviously be tricky work if you sand through all the
layers and create a hole. Composite airplane wings have a foam
core, so this is not a problem for them. You could attempt to
leave a couple layers, and add a couple of extra layers on top
to compensate. I'm not sure how you judge when only a "couple
layers" are left, adding to the challenge. You might also
figure out a way to glue a piece of foam inside the mast before
you start, then if you sand through you'll be ok.

I've done a fair amount of hand layup of composites, and I
would rate this procedure towards the "advanced" end of the
spectrum. I would practice on something other than your mast
until you're comfortable with the layup work.

Booms

Goose neck

782

Posted by: George Saunders on February 05, 2003 at 16:51:04:

I am re rigging my boom and plan to replace the "goose neck" which is currently a 1/4" piece of ply wood with delrine. What shape should I use? I could just copy the old one. I live in Maryland and only get out a handful of time a year; I'd like to get it right the first time. It seems that you make get some (very little) control over mast rotation by controlling this profile. Any thoughts? (BTW the boom has to be ready by 2/7.)

-George

783

Posted by: GeoffS on February 05, 2003 at 23:30:31:

In Reply to: "Goose neck" profile posted by George Saunders on February 05, 2003 at 16:51:04:

As you observe suggest, the profile isn't very crtical.
Anything similar to the profile shown on the official
plans should work fine:
http://www.eissegeln.de/tceurope/plans/plan5.gif

Note that the sail-feed cutout in the aft part of of the
mast may fall in the section of the mast that the boom
slides across as you sheet in and out. In that case you
may want to ensure that the fork is smooth enough not to
catch on the cutout.

Cheers,

Plank and Chocks

Plank construction

780

Posted by: D.WALK on February 02, 2003 at 13:02:45:

To all the experts is it important to glue a plank so the grains of the top,middle, and bottom layers form as the rings in a tree look. Viewing end grain of plank.

785

Posted by: Paul Goodwin on February 10, 2003 at 13:54:21:

In Reply to: Grain construction posted by D.WALK on February 02, 2003 at 13:02:45:

Many people go along with the idea that it is best to glue up the plank so the grain direction lines up like the rings of a tree -- I'm not one of them...

Actually, I think most knowledgable builders would agree that the best orientation for the grain is quarter-sawn (with the grain orientation perpendicular to the face). Show me a tree with radial rings!!!

That being said, if you have flat-sawn wood, then orienting the grain to look like a tree certainly can't hurt, so why not do it that way and then nobody will say you did it wrong.

Wood Sources

823

Posted by: Paul Goodwin on November 05, 2003 at 23:51:20:

In Reply to: Dimensional ash wood source needed in MI posted by George on November 05, 2003 at 15:04:39:

THE source for hardwoods in SE Michigan is Armstrong Millworks, on
M-59 in Highland (East of M-23). They've been in the business
longer than I've been alive, and stock a huge selection of local
and exotic
hardwoods.

Call ahead of time to check their business hours.

Where you step

401

Posted by: Rick lemberg on September 01, 1999 at 19:41:44:

In Reply to: ?Rubber pads for the planks

posted by brian jones on August 31, 1999 at 17:12:55:

try your local flooring store .their are several rubber flooring products one the market , I myself use a rubber stairtread and contact cement them on, you can replace them when needed.

Plank Stiffness and Crown

Changing stiffness

735

Posted by: ken schykulski on December 16, 2002 at 20:06:59:

In Reply to: Plank construction details - here's what I do... posted by Paul Goodwin on October 12, 2001 at 08:15:28:

It's the other story I'm interested in right now. I have a two ply sitka plank right now that is far too stiff for me. As I think about making another one (maybe hollow) I wonder what kind of crown I should use in glueing it up. I weigh about 140-145lbs. Any suggestions on a crown to start with for 2 ply construction, 3 ply or hollow?

Thanks,
Ken

736

Posted by: Paul Goodwin on December 16, 2002 at 22:08:41:

In Reply to: Re: Plank construction details - here's what I do... posted by ken schykulski on December 16, 2002 at 20:06:59:

If you decide to build a new plank, I would recommend a 3-piece
solid core plank. I wouldn't build anything else for myself these
days, certainly not hollow. If had a few hollow core planks break
while sailing, and I've never broken a solid plank.

I also have a functional 2-piece solid Sitka plank that is the
lightest plank I own, 16 pounds with chocks. I built it in 1984
and used it in the 1985 Worlds, plus several years after. It is
still the only plank that fits my spare boat, the "Barnegat Bay
Flyer", and it works perfectly.

So... considering you already have a 2-piece Sitka plank, I would
rebuilt it into a plank that works for you. Resaw the plank into
two pieces on a band saw, then glue it back together with the
desired crown. The problem is, springback on a 2-piece plank is
pretty large, and somewhat unpredictable. It's been so long since
I've made a 2-piece, I don't even know where to start with a
recommendation for springback.

The good news is, if the plank is too stiff for you, then it is
probably thicker than it needs to be. This means you can resaw
it, glue it, and if the crown isn't what you were trying for, you
can resaw it again. You'll lose some thickness each time you
resaw, but that's good as long as you stay over the minimum
(plank stresses are lowest with a minimum thickness plank).

Now for crown recommendations. I'll recommend 2-1/4" crown, and
1-3/4 inches deflection with your weight. This might be more or
less flexible than is in vogue in some areas, but it works for
me - YMMV (your mileage may vary). I'm not sure how much crown
to put into the plank when you glue it. If I was to take an
initial stab I would figure 3" or 4" of springback.

Make sure to glue it well, using epoxy thickened with cotton
flock (microfibers). I'd leave it clamped up for at least a
couple days to make sure you get a full cure. There is a lot
of stress on the glue joint in a 2-piece plank.

345

Posted by: Bob rast on December 15, 1998 at 09:04:48:

In Reply to: Plank stiffening posted by Ed Atkeson on December 07, 1998 at 09:24:41:

348

Posted by: Paul Goodwin on December 17, 1998 at 08:24:00:

In Reply to: Re: Plank stiffening posted by Ed Atkeson on December 16, 1998 at 08:25:09:

Don't use plywood. The cross grain fibers add nothing to the
stiffness and actually detract from the stength. Voice of experience.

Veneers work very well, but you need a vacuum bag to use them
properly. A wood strip is easy to do and works. I have also had
good luck with fiberglass - the damping factor in a fiberglass
layup is generally lower than for wood, so I don't see how you can
"deaden the spring effect". By the way, all of Ron Sherrys' planks
are covered with fiberglass - I'll be sure to let him know his
planks are dead!!! :-)

350

Posted by: Ed Atkeson on December 17, 1998 at 15:45:39:

In Reply to: Re: Plank stiffening posted by Paul Goodwin on December 17, 1998 at 08:24:00:

PG>>> Veneers work very well, but you need a vacuum bag to use them properly. A wood strip is easy to do and works. I have also had
good luck with fiberglass - the damping factor in a fiberglass layup is generally lower than for wood, so I don't see how you can "deaden the spring effect".
-------------------
Meanwhile I called the Gougeon people and ordered some 3 inch unidirectional fiberglass tape to apply to the underside of the plank. I plan to give the plank half an inch more crown and just glue it on. Does this sound like a good plan?

thanks for all the helpful replies,
Ed A

349

Posted by: Paul Goodwin on December 17, 1998 at 08:36:44:

In Reply to: Re: Plank stiffening posted by Paul Goodwin on December 17, 1998 at 08:24:00:

When remarking that you need a vacuum bag to apply veneers, apparently
I went momentarily brain-dead and forgot about the poor mans vacuum
bag - stretch film. This most excellent material looks like thick
Saran Wrap and comes in rolls. You stretch it out as you wrap it
around the plank and it sticks to itself, creating a high tech
pressure bandage. The more you stretsch and wrap, the more pressure
you build up. I'll bet you could even build up more ultimate
pressure than with vacuum.

Twisted Plank?

818

Posted by: DAVE CLAPP US5116 on October 27, 2003 at 09:03:40:

MY PLANK HAS A LITTLE TWIST TO IT , THE CHOCKS ARE LEVEL AFTER PADDING BETWEEN CHOCK AND PLANK.IS THIS JUST A MENTAL SETBACK OR A REAL PROBLEM. ( TO BUILD OR NOT TO BUILD, THAT IS THE QUESTION)
Carefull to not backspace too much, the form may crash and
start wiping out and overstriking what your writing.

819

Posted by: jane on October 27, 2003 at 13:44:15:

In Reply to: RUNNER PLANK TWIST posted by DAVE CLAPP US5116 on October 27, 2003 at 09:03:40:

The critical consideration is whether the degree of twist changes as the plank is loaded up when sailing. If the degree of twist changes, then the runner alignment will likely change. This is not good.

820

Posted by: Geoff Sobering on October 27, 2003 at 15:33:45:

In Reply to: Re: RUNNER PLANK TWIST posted by jane on October 27, 2003 at 13:44:15:

Probably the easiest way to check to se if you have a problem is to setup the plank with a set of runner aligners (it helps to have the hull attached, but you can do this with just the plank and rear-runners). Align the runners (or note the degree of misalignment very carefully) with the plank unloaded. Carefully add weight onto the plank up to the normal sailing load (ca. your weight plus about 150 lbs). Watch the alignment as the plank deflects. If the runner alignment doesn't change then the twist isn't a problem. If it changes...

Remember that small changes make a big difference!

821

Posted by: John Davenport US4961 on October 27, 2003 at 16:51:41:

In Reply to: RUNNER PLANK TWIST posted by DAVE CLAPP US5116 on October 27, 2003 at 09:03:40:

Dave, Another thing to remember is that as the plank is loaded and the aft part of the boat lowers, the front does not. That means the bottom of the boat (where the plank is attached) changes angle and therefore the plank too. There is a great article by Jan Gougeon describing how he shims the plank to the boat in the powered-up mode so that the plank is parallel to the ice while sailing. I say just build or buy another plank and see. Also you can try a different stiffness and see if that helps too! We will be sailing out first regatta in MN in 5 weeks!!!!
See you at the NA's!

Crown

[From Paul Goodwin post above, #736]

744

Posted by: ken schykulski on December 31, 2002 at 13:56:08:

In Reply to: Re: Plank construction details - here's what I do... posted by bob Rast Dn11313 on December 18, 2002 at 07:53:46:

The amount of crown for a runner plank suggested by Paul and Geoff suprise me. I have two sets of plans (the Association's plans from about 1978 and the Gougeon plans from 1974) which call for 2" of crown for a 1 3/8 thick solid 2-ply plank and 1 1/4" crown for a hollow plank with a 7/8" core, respectively. My current 2-ply plank has 1 1/2" of crown and at best will flex to a level position. For a plank to flex from 2 1/4 positive to 1 3/4 negative suggests to me it would have to be very thin and very flexible. Am I missing something here? Does thinning a solid plank by 1/4" give an additional 2 1/2" of flexion? Does a hollow plank with a 3/4" core give 4" of flexion? How thick should a core be to give that kind of flexion for different weights?

Puzzled,
Ken

745

Posted by: Bob Rast on December 31, 2002 at 14:05:54:

In Reply to: Re: Plank construction details - puzzled... posted by ken schykulski on December 31, 2002 at 13:56:08:

I think you are misinterpreting the numbers . The plank at rest has about 2 1/4 of crown and with your weight should deflect approximately 1 3/4 which is just about 1/2 above flat or 0, not 1 3/4 past 0 which would be way too much. From my experience a plank with 2" of deflection is soft and some guys are going to about 1 5/8 which is stiff. I wouldn’t rely on the old numbers as things have changed in the past 5 years with the softer fiberglass masts.

Spring back, Gluing layers

737

Posted by: Geoff Sobering on December 17, 2002 at 09:05:27:

In Reply to: Re: Plank construction details - here's what I do... posted by Paul Goodwin on December 16, 2002 at 22:08:41:

> The problem is, springback on a 2-piece plank is
> pretty large, and somewhat unpredictable. It's been so long since
> I've made a 2-piece, I don't even know where to start with a
> recommendation for springback.

One place to get a first-approximation of the springback is
the formula the Gougeon’s list in the WEST System User Manual:

springback = initial crown / ( number_of_plys^2)

Using this formula, if you want Paul's suggested 2 1/4" final
crown, you should clamp a 2-part plank with 3" of crown:

spring back = 3" / ( 2^2 ) = 3" / 4 = 3/4"
final crown = initial crown - springback = 3" - 3/4" = 2 1/4"

That's a pretty big correction to calculate with such a simple
formula, so I'd be a bit skeptical of it's accuracy. It's
probably as good as you'll find for an estimate, and it's in the
same ballpark as Paul's 3"-4" estimate.

The formula's available on-line via: http://westsystem.com/
Follow: Using WEST System Epoxy -> User Manual -> Tips & Techniques
(http://westsystem.com/webpages/usingepoxy/shoptips.htm)

Cheers,

Geoff S.
US 5156

839

Posted by: wayne matheson on January 23, 2004 at 13:44:37:

.I am building a plank 5\18 ash strips top and bottom 17\32 spruce strip core . I glued it into panels then laminated them together on a jig 3" on center and 2.5"at 2 feet The plank ended up with a crown of almost 2 7\8 , Other planks that I have built have been of slabs of ash and spruce and those planks had much more spring back . Does sawing the wood into strips take out the inherent tension of the wood? If this is so then other people who are considering this method of construction should take this into consideration when building their jigs. Has anyone else had similar experiences? What is the down side of a high plank? Also I was wondering if the recommended 1 3\4 deflection for a flexi plank referred to before or after glassing.

840

Posted by: John Jombock DN US 1513 on January 24, 2004 at 17:25:01:

In Reply to: spring back -not posted by wayne matheson on January 23, 2004 at 13:44:37:

Springback in Runner Planks - Why Guess ? ( 2004 Update )

Wayne -

I read with great interest your report on the disappointingly low
springback inan ash-faced plank you built . Although I'm not
completely sure on the dimensions of your plank and your jig ,
I think the following example will explain why you got so little
springback and so much crown in your plank .

Let's build a plank with ash-strip skins ,or faces, and a 17/32in.
spruce core . The total thickness of this plank is 1-5/32in. ,
or 1.156in . The ratio of face thickness to total plank thickness
is 0.3125/1.156=0.270 . The expected springback will be 12.7 per-
cent of the crown in the jig (you expected more?) . If the crown
in the jig is 3.29in. , the crown in our finished plank will be
about 2-7/8in . How do I know this ? Quite simple - I referred to
to the charts in my June,1991 article on springback in the IDNIYRA
Newsletter (the IDNIYRA Newsletter later became Runner Tracks) .
My article tells you everything you need to know about springback
in runner planks .

If you want the final crown in the above-described plank to be
1-3/4in. , you should use a jig with a crown of 1.146x1.75=2.01in.
The springback would be 12.7 percent or 1.27x2.01=0.26in. and the crown in the plank would be 2.01-0.26=1.75in. , the crown you
wanted .

If you don't have access to the 1991 Newsletter article , send me
$3.00 and I'll rush you a copy .

John Jombock
136 Applewood Lane
Slippery Rock, PA 16057
724.794.4425

Hollow Planks

Posted by: bob Rast Dn11313 on December 18, 2002 at 07:53:46:

In Reply to: Plank construction details - here's what I do... posted by Paul Goodwin on October 12, 2001 at 08:15:28:

I built a hollow plank 2 years ago and it worked well for my weight , about 165Lbs. I used strips of Sitka about 1 3/4 x 3/8 +- in the center for each edge with solid blocking above chock area and where stud plates fasten. In the center of the plank we just ran a couple of strips on a diagonal and used ash for top and bottom skins about 3/8+-. the plank came out minimum weight with chocks around 20 lbs and performed well. It even took a hit from another DN head on and just crushed a small area of the front edge which was easily repaired. As usual I planed it down too much and have added fiberglass on top and bottom to stiffen.

Bottoming out-Advanced Tuning

396

Posted by: Jordan Glaser on February 08, 2004 at 21:15:03:

It was blowing link stink on the Navesink today (20mph with gusts to 39mph). The DNs, Arrows & Yankees all sailed. Last year I switched from an aluminum to carbon mast. I weigh around 210. In today's heavy wind I was able to go very fast but bottomed out the plank or back of the boat numerous times. I noticed that the DN wasn't pointing as well as some of the other boats. Could this be related to the need for more plank stiffness?

397

Posted by: Paul Goodwin on February 09, 2004 at 23:22:26:

In Reply to: DN bottoming out affect pointing? posted by Jordan Glaser on February 08, 2004 at 21:15:03:

If your boat is bottoming out, your plank is definitely
too soft for use with your new mast. The composite mast
is softer than your aluminum mast, and will perform better
with a stiffer plank.

When the plank bends too much, the result is too much side
rake in the mast, and overbending the mast. This is at
least part of your pointing problem. When the wind picks
up you should tighten the rig to control mast bend.
The best way to do this is too tighten the forestay,
which rakes the mast forward (and also tightens the
side stays at the same time), and then lower the sail
on the mast.

You should also make sure you set your mainsheet blocks
so they pull back aggressively to derotate the mast at
top speed. This tightens the leech of the sail and
allows for better pointing, and also reduces the draft
of the mast/sail to lower the drag.

398

Posted by: Jordan Glaser on February 10, 2004 at 08:00:39:

In Reply to: Re: DN bottoming out affect pointing? posted by Paul Goodwin on February 09, 2004 at 23:22:26:

Thanks for the response Paul, I'm sure it will be of great help until I get the plank stiffened (?S glass). Some of the suggestions sound like a lighter air set up (tighter stays, less rake, boom pulleys foward with mast derotation). Once the plank is stiffened or I lose 35 pounds (ha ha), how much would I revert the set-up for high gusty winds? I know that each DN has its own personality.

399

Posted by: Paul Goodwin on February 11, 2004 at 08:39:24:

In Reply to: Re: DN bottoming out affect pointing? posted by Jordan Glaser on February 10, 2004 at 08:00:39:

Actually, I think you've got the rig tuning steps backward, at
least by my way of thinking.

In light air, it's difficult to get the mast to bend, so the
rig tuning should be in a direction that minimizes stiffness.
In light air I would move the mast step forward and increase
mast rake. It sometimes also helps to have neutral pull-back
on the mainsheet, or only slight derotation. Less rotation
allows the tip to bend and promote twist in the sail, and
increases the effective draft.

In strong wind, the mast bend will tend to get out of control,
so you should move the mast step back and decrease mast rake.
Also pull back aggressively on the boom to derotate the mast.

In all cases, I try to maintain the same distance between
the boom blocks and the deck. All else being equal, if you
increase this distance by raising the halyard, you will get
more mast bend at top speed. It won't be easier to get the
mast bend started, it will just ultimately bend more because
you can pull in more mainsheet. This assumes you sail with
the mainsheet two-blocked, as I always do.

If it's really windy and the mast is bending too much (even
after moving the mast step back and decreasing rake), then
lower the halyard so you can't pull the mainsheet in so far.

Unidiredtional glass (S or E) on the bottom of the plank
is a very quick fix. Just be careful not to stiffen too much,
the stuff is difficult to remove. It's much easier to add a
little more than to grind it off.

400

Posted by: dave on February 11, 2004 at 16:13:10:

In Reply to: Re: DN bottoming out affect pointing? posted by Paul Goodwin on February 09, 2004 at 23:22:26:

Paul, I have Brieden's Sherry experimental glass mast and find, with a relatively stiff plank(neutral), I have to move step forward and loosen forestay to allow mast to pop out in gusts. It has a nice gradual curve in light airs set up tight, but I can't seem to sustain good mast bend while 2 blocked. The mast has obviously had 2 extra layers added from base to appox. 1 1/2' above hounds. I've had people tell me you guys did this to give more side to side stiffness in order to promote better rotation. I suspect this extra layup has the mast too stiff now for my 190# frame. If any of this makes sense, would removing this extra layer improve or forever damage the masts properties?...Dave

402

Posted by: Paul Goodwin on February 12, 2004 at 07:57:56:

In Reply to: Re: DN bottoming out affect pointing? posted by dave on February 11, 2004 at 16:13:10:

The Experimental masts were very successful, I still have
(#6 I think) and use it occasionally. I think this mast has
more hard driven ice miles on it than any other composite mast
out there.

Once the experimental period ended and Ron went into "real"
building, the layup didn't change for quite a while, and this
design became the "Standard Whip".

Later the tip was stiffened to help with rotation, and the
new design became the "Stiff Tip Whip". The Stiff Tip is
still the standard all-glass design in the Sherry lineup.
After that came a Carbon Standard to reduce weight, then
various softer versions for sailors that were less mass
challenged.

So much for history...

During the Experimental stage, production techniques
were being developed, and there was some variablilty
in the stiffness. If there was glass added to your
mast, I suspect it was to increase the stiffness, not
help with rotation. As far as I know we never added
glass on the bottom section to help rotation, especially
on the sides. If we were going to add glass to promote
rotation, it would be on the fore/aft axis.

You can try removing some of the glass, although it is
a bit difficult to remove a layer uniformly. Take your
time and watch carefully to control how much you are sanding off.

You haven't said how far you've moved the mast step,
but at least your going in the right direction. Move
the mast step all the way forward, and adjust your
forestay so there is 10-12" that you can pull down
the boom before it two-blocks (16" or so between the
bottom of the boom and the deck). The basic setup
would be to have the side shrouds just go limp when
you stand on the plank, although you could go slightly
looser to help promote bend. Also, make sure you pull
back on the boom to derotate the mast under almost
all conditions.

I keep the sail pretty low on the mast, but if you
are having problems getting the mast to bend, raise
the halyard and rake the mast back more. Getting
the mast to bend is important for reaching top
speed and pointing.

404

Posted by: Dave on February 12, 2004 at 16:11:57:

In Reply to: Re: DN bottoming out affect pointing? posted by Paul Goodwin on February 12, 2004 at 07:57:56:

For the record this mast is registered as #0257 "Experimental"....not sure you guys archived their properties ? The mast is very heavy compared to new, must be the resin/glass ratio !!

To clear things up in my mind, for anything but light air sailing, should the mast be mechanically "loaded"(popped) in steady air ?

Observing many pictures, one may tend to think this is true, although I'm not sure in all instances, optimum !

"Block to block", the minor axis(fore/aft)is already maxed out. If so, then the ensuing gust response mechanism must be plank yield and further leeward deflection.

My plank is of the "indexed" (unajustable)type, so fixed. I subscribe to the "Detroit" notion ie fixed shroud length at 136". With mast located one back from furthest step forward, I achieve approx. the 16" off deck you prescribe. At this point the shrouds(constant length)are just tightening or slack when plank is loaded, with the rake approx. 71 degrees off horizontal. Your comments as to sail height lead me to believe you wish to lower the CE while facilitating the ease to which one can obtain and maintain the "2 block" state. I've certainly found this to be almost imperative, ie. it's almost impossible to manhandle the sheet load otherwise. Anyway, with these settings and halyard lowered, this particular mast, maintains a continuous arc top to bottom, and will not "pop" unless hit by 15k plus gusts !

So do I loosen things further(136" shrouds, slack) ?...this certainly helps at the expense of pointing (ugly VMGs). But then I worry about inducing complete failure ! You seem to infer this with your last comments re more rake, more sail height.

Thanks Paul for all the comments....Dave

405

Posted by: Ken on February 12, 2004 at 19:49:55:

In Reply to: Re: DN bottoming out affect pointing? posted by Dave on February 12, 2004 at 16:11:57:

Ron's formula for tuning certainly works for the Detroit crowd especially. I would not weld myself to that exact side shroud number because:
1. My boat is not a Clone, and the side boards at the mast and at the bow and at the stern blocks (the whole deck profile) is different.
2. I am fat.
3. My mast is not a Sherry spar. It is either stiffer or softer depending on whether it has its stick inside or not.
4. My sail is not the same shape as Boston's F0-1 and the leach is shorter by 6 inches.

Even Roon says that 136 inch side shrouds is a starting point for tuning a boat. Not the end.

Your mast's gotta bend to go fast and point. Changing the setup, as Paul suggested, will achieve that. If the mast is stiffer, it can still go fast, but you have to both work and pull harder.

Ken Smith

409

Posted by: Paul Goodwin on February 13, 2004 at 12:13:24:

In Reply to: Re: DN bottoming out affect pointing? posted by Dave on February 12, 2004 at 16:11:57:

"This mast is heavy compared to new". I'm not sure what
you're comparing the weight to. The new carbon masts are
5 or more pounds lighter, and it feels like even more when
you pick one up. I'm sailing with a "stiff tip" mast
(all glass) that I got a couple of years ago, and it's
about the same weight as my experimental mast.

The experimental number you refer to was issued by the
IDNIYRA, and I'm not sure how that relates to the build
number of the first batch of Ron's masts. There was a
group of about 6 local sailors that got together and
built the first masts. The first mast was a complete
failure (the tip didn't fill the mold), but was useful
for doing a "stress to failure" test on the bottom section.
The second was far from perfect, but was good enough to
put a sail on and get on the ice. Numbers 3 through 12
(if my old-timer memory is correct) were all registered
with the class, and I think most are still sailing (or
at least used as backups like mine).

I don't think of getting the mast to "pop-out" as being
a mechanical thing, except maybe in light wind where
there just isn't enough sail load to get the mast to
bend on it's own. I think to reach top speed, the mast
must bend or the drag of the sail limits the speed, even
in light wind.

In most conditions, my rig is set up so that as I
accelerate off the starting line, the mainsheet is
gradually pulled in till the rear blocks are about
3"-4" apart. As the boat increases in speed, the
apparent wind also increases, and the load on the
sail causes the mast to start bending. As the mast
bends the sail flattens, and the top of the sail
starts to twist off due to the reduction in leech
tension.

At this point I begin pulling in the last bit of
mainsheet, which de-rotates the mast. Mast de-rotation
does two things: firstly it aligns the stiff fore and
aft axis of the mast with the sail, which tightens the
leech and allows you to point higher; secondly it
reduces the apparent cross section of the mast, resulting
in less draft. The net effect is reduced drag, and this
allow the boat to point higher and accelerate to a higher
speed (Jan Gougeon coined the term "warp" for this
overdrive gear).

Plank deflection loosens the side stays, which increases
mast bend due to rig compression. Loose side stays (mast
side rake) also reduces the effective area of the sail,
so is generally not a good thing in light wind. However,
it's more important to promote mast bend in light wind,
so loose stays are ok if this is what it takes to get
the mast bending.

Ken Smith makes several good points in his reply, and
Ron sherry's tuning tips are geared towards his "clone"
design or at least boats very similar. So as Ken said,
the 136" shroud length is just a starting point.

Once set up and working well, my rig will bend easily
once the boat is up to speed, and puffs cause additional
rig to bend with little hiking. When things are really
working, I rarely have to ease the mainsheet in puffs;
instead a small hike is controlled by pointing higher
until the wind eases.

410

Posted by: Dave on February 13, 2004 at 16:23:45:

In Reply to: Re: DN bottoming out affect pointing? posted by Paul Goodwin on February 13, 2004 at 12:13:24:

This "experimental" mast by your account must be one of twelve registered. Compared to new it is nearly 1/3 again heavier. If the fabric content is close than I attribute extra weight to resin volume, which in general should not affect mast deflective properties.There may be more to the extra 3/4 length layup than meets the eye, I'm not sure, but certainly adds weight.

I think there's a large misconception among users that the flexible masts allow the leech to dump, induce twist, and thereby make the boat easier to handle. Nothing could be further from the truth as you so aptly describe with your takeoff technique. I'd like to add a new "twist" to your take. You describe what could be called "momentary" twist as the sheet is pulled in. Until fully sheeted the rotation compromises the attack angle of mast to the ever decreasing apparent wind's angle. The induced batten pressure on the luff, and consequently the leech, does not produce favorable camber until sheet tension creates a rotation that aligns the mast and leech on a plane with the apparent. Cranked block to block eliminates twist which is catastrophic to the sails leeward suction, the lack of which is the drag, as you point out. All said, we need to think of twist as the enemy, not a means of control as with the soft water boats. The stiff tip really is another means to control twist as it points to windward, hooked as a bird's wing, ultimately controlling the leech's alignment. This is even more beneficial off the wind, where the wind is still apparent.

You mention plank stiffness, the deflection of which, puts the now loosened stays at a favorable angle to compress the leeward mast. The flex mast trend seems to be toward ever stiffer planks, thereby reducing the stays compressive affect, unless they are loosened manually. This leads me to the conclusion, if you want to point(vmg), don't loosen stays, go for the softer mid-mast !

Controlling the puff, or momentary change to the apparent, becomes paramount. As you describe Paul, accepting a little hike, as opposed to, too soft a mast, can be the "grey area" between winning and losing !

So these simple little rigs are damn complicated aren't they ???

411

Posted by: Geoff Sobering on February 13, 2004 at 22:54:14:

In Reply to: Re: DN bottoming out affect pointing? posted by Dave on February 13, 2004 at 16:23:45:

While were on the topic of tuning these "simple little rigs", I'm wondering what the current thought on the position of the mast-cup is?

Back "in the day" (of Aluminum masts) many people would position the cup near the front of the mast and use forward force on the boom to induce more mast rotation and consequent bend. When I first started sailing with a composite mast (a very soft one), I moved the cup all the way aft to limit rotation and bend. Currently, I'm sailing my stiffer mast with the cup one position (ca. 1-1/2") forward from the aft-most position, and I think I'm having trouble de-rotating the mast to get into "warp mode" with the blocks interleaved. I was wondering if moving the cup a bit further forward would be helpful?

More generally, what is the interaction between the sail-pressure induced mast rotation and boom-force induced mast rotation?

Cheers,

Geoff S.
US-5156

412

Posted by: Paul Goodwin on February 14, 2004 at 08:53:26:

In Reply to: Re: DN bottoming out affect pointing? posted by Geoff Sobering on February 13, 2004 at 22:54:14:

One comment to start with. I can't think of any condition
where I would push forward with the boom to induce rotation,
never did with a Kenyon or Norton aluminum mast, and haven't
with a composite mast - except as an experiment to see what
would happen. My range of settings is from neutral to pulling
back really hard. Using mast rotation to induce bend is a
win/lose situation. You get more fore and aft bend to flatten
the sail, but you increase the effective draft (by rotating
the mast sideways relative to the apparent wind) and create a
very draft forward shape. It's much faster to derotate the
mast at high speed, and use rig tension (compression on the
mast) to create the desired bend.

Mast cup position - when Ron and I were sailing Kenyon
aluminum masts, we always carried the cup in the aft hole.
When we went to composite masts we had some problems getting
the mast to rotate under certain conditions, and we moved
the cup forward in an effort to get the mast to rotate
easier. It seemed the further forward you put the cup,
the harder it was to de-rotate, so we kept it as far back
as possible. After a little experimenting, we put it in
the second hole forward and have left it there ever since.

I think moving the cup forward will make it harder to
de-rotate, not easier. However, there is no harm in trying,
and you may find an advantage that I'm unaware of.
My only request is that since I spilled my guts, if
you find out anything of value from experimenting with
mast cup position, please share...

413

Posted by: Geoff Sobering on February 14, 2004 at 10:15:37:

In Reply to: Re: DN bottoming out affect pointing? posted by Paul Goodwin on February 14, 2004 at 08:53:26:

> I think moving the cup forward will make it harder to
> de-rotate, not easier. However, there is no harm in trying,
> and you may find an advantage that I'm unaware of.

My gut-feeling was the same; I just wanted to make sure I wasn't missing something. Sometimes there are subtleties gleaned from experience/observation that are counterintuitive.

The reason I even started thinking about this was that the lever-arm between the mast rotation axis and luff-tube at the height of the boom increases as the cup is moved forward. This should increase the effect of any force applied via the boom. It should also increase the effect of aerodynamic force from the sail. Based on your observations, my guess is that the aerodynamic forces are much greater than the boom can counteract, and reducing them is the important factor in getting the most de-rotation. It may also be that there are a completely different set of forces (ex. transferred from the leech to the mast-tip) that are dominant.

> My only request is that since I spilled my guts, if
> you find out anything of value from experimenting with
> mast cup position, please share...

Absolutely. Will do!

It looks like my next sailing opportunity will be at the NA site on Friday. I have a bunch of rig changes to sort out, but if I get through the basics I'll play with position a bit. I doubt I'll discover anything new.

414

Posted by: Dave on February 14, 2004 at 11:17:08:

In Reply to: Re: DN bottoming out affect pointing? posted by Geoff Sobering on February 14, 2004 at 10:15:37:

With the "active/reactive rig), the boom will only do what the batten tension and ensuent camber will allow....the only boom control we have is how hard we pull....so the difference between over-rotation and favorable de-rotation is the final sheeting that nestles those blocks. The question then becomes whether or not we have a favorable mast flex/sail/batten marriage..........the cup should not matter much, except in hockey. I use the lever above at the hounds (believed to be Struble's), it counters any cup location nicely, and as expected, has no influence on the mast's and batten's ability to de-rotate. Having the blocks situated to neutralize the boom serves to decrease luff wear and tear mostly........

....but then those damn shrouds....????

Plank Profile and Drag

Posted by: R Cummins US3433 on January 18, 2000 at 12:58:06:

In Reply to: Wind Tunnel Tests of Runner Planks posted by Brack on November 18, 1999 at 22:55:46:

Once upon a time, about twenty years ago, we did some work on this sort of thing. Low speed wind tunnels are interesting, and you can come up with some drag coefficients and other numbers that may or may not tell you much. I have also had the opportunity to listen to the airplane folks at EAA talk about this sort of thing at length.

Aerodynamic shapes are better, and you need to keep that in mind when you build things. Rounded edges are good, airfoils are better, but how much is hard to say. If you want to go nuts, you can (or could) get airfoil shaped cable from the airplane folks.

The real problem is surface friction. Your body presents more irregular surface area than anything else in the boat. This is the reason that many of the top racers wear skin tight body suits when they are sailing.

In the end, I would spend my time making sure the plank doesn't twist the runners out of alignment when it flexes. A plank that twists the runners out of alignment is likely have a greater adverse effect on speed than a plank with square edges.

Posted by: Bob Dill on January 19, 2000 at 09:30:39:

In Reply to: Re: Wind Tunnel Tests of Runner Planks posted by R Cummins US3433 on January 18, 2000 at 12:58:06:

Aerodynamics of runner planks:

The DN experiences a maximum apparent wind of about 50 mph (in 20+ true wind) at more moderate true wind speeds 40 mph apparent more typical. A 1.25" thick runner plank has about 0.6 square feet of frontal area. The drag coefficient of a long narrow rectangle is about 1 giving about 2.5 lb of drag at 40 mph apparent. Simply rounding the leading edge will reduce the drag coefficient to about 0.5 and making an elliptical plank section will get you down to about 0.1 or 0.2. I strongly recommend rounding the leading edge. Elliptical sections are pretty easy to do. Full airfoil sections are not worth the bother. Overall the plank is one of the bigger aerodynamic factors that you can do something about. Bob Cummins suggestions about clothing are right on the money as well.
Bob suggested airfoil stays (if you want to go nuts). They work very well on biplanes as between the wing tension members. They do not work well on boats for several reasons. The angle of attack of the stays changes too much on opposite tacks. The loose stay will tend to get sideways creating even more drag than a round wire. The tensioned stays may tend to oscillate as they are too long to have enough torsional rigidity to prevent this. If that is not enough, they will run afoul of the class rules.

Bob

Chocks

880

Posted by: Corey Hughes on June 03, 2004 at 13:29:28:

In Reply to: Side Chocks - recommendations? posted by Geoff Sobering - US-5156 on May 05, 2004 at 22:14:45:

Geoff:

Dan Nevedal (GTIYC in Traverse City, MI) makes a great custom chock. Bob Gray and several others here in the club are using them and seem to be very happy. Cost is quite reasonable, especially considering the great care he takes in their construction. Drop him a note. I would give you his phone number, but he just moved about 20 miles South of town and most likely has a Cadillac number now. If the email won't work for you, let me know and I'll get his new number.

daneve2@earthlink.net

By the way, thanks for the great photo updates on the Renegade construction. I am following it very closely. Wish that I lived closer.

Think Ice
Corey Hughes
Nite 341

879

Posted by: Ken Smith on May 12, 2004 at 07:35:18:

In Reply to: Side Chocks - recommendations? posted by Geoff Sobering - US-5156 on May 05, 2004 at 22:14:45:

Options out there include:

Hammel Chocks. Last I checked, there were none in stock and Mr. Hammel had not ordered another run to make them. Jeff Kent has some he sells with his planks. Hammel is a listed supplier on the main site. These chocks are stiffer than Sarns chocks and the inside side is curved to spread the stresses. I cannot say whether or not they are machine-finished for straightness.

Jablonski chocks. Similar in size and weight, but diferent details than the Hammels. They have a lip on the inner face to add stiffness fore and aft at the lower edge. I got a pair in Poland, but do not know a source except through personal contacts. Mine include a counter-sunk attachment bold and are threaded so a nut is not required. Pete Johns may be able to arange shipment through his Polish friends.

Strubble chocks. Matt designed an extrusion including a web from the inner face to the base. They are carefully machined, light, stiff and straight. Mat fits them with a press-in nut and a countersunk bolt so only an allen wrench is needed for installation. Matt has made quite a few. Ron Sherry will supply them or call Matt.

I used Strubble chocks on my new plank and recommend them for their quality and for their availability.

Ken DN 4137

Alternatives

470

Posted by: Konrad on January 08, 2000 at 17:51:55:

If you need runner chocks and hesitate at the prices of stock chocks, here's (hopefully) an image of the chocks I use.

They are made from 1/4" extruded aluminum and are called F-Brackets. They are the base anchor for aluminum storefront glass curtain walls. They work perfectly with the right spacer thickness.

My stainless steel blades are 1/4" thick, and the inside dimension between the legs of the bracket required two spacer blocks exactly 7/16". I went to K-Mart and found a cutting board for 7 bucks that was exactly that thickness. Perfect! And then I just ran it through the table saw to cut the board to the right size. Worked great.

Because I work in commercial construction I scored my F-Brackets for free, but my buddies at the glass company said they would have sold them to me for about 10 bucks a piece. Probably a lot cheaper than the stock stuff, but that's just a guess. So the whole set up would be about 40 bucks. DN blades my be some other thickness than mine, so a different spacer would be needed if so.

You can't get F-Brackets at a typical window place or lumber yard, they come from glass companies that do aluminum store fronts, and the guys I know say they have lots of them laying around in thier shop.

Hopefully the image will show.

Konrad

878

Posted by: Geoff Sobering - US-5156 on May 05, 2004 at 22:14:45:

I'm planning to upgrade the chocks on my plank before next season (currently a set of Sarns). I know there are a number of better chocks out there, but I don't have a complete list, and I certainly don't have any good reasons to choose one over the other.

1) I'd love to get some photos (or links to photos) of the different kinds of chocks so I can identify them (and place a name on the ones I've seen on other people's boats).
2) Some suggestions on what the advantages of the different makes/styles.
3) Pointers on who sells them.

879

Posted by: Ken Smith on May 12, 2004 at 07:35:18:

In Reply to: Side Chocks - recommendations? posted by Geoff Sobering - US-5156 on May 05, 2004 at 22:14:45:

Options out there include:

I used Strubble chocks on my new plank and recommend them for their quality and for their availability.

Ken DN 4137

880

Posted by: Corey Hughes on June 03, 2004 at 13:29:28:

In Reply to: Side Chocks - recommendations? posted by Geoff Sobering - US-5156 on May 05, 2004 at 22:14:45:

Geoff:

daneve2@earthlink.net

By the way, thanks for the great photo updates on the Renegade construction. I am following it very closely. Wish that I lived closer.

Think Ice
Corey Hughes
Nite 341

Mounting chocks to plank

385

Posted by: Paul Goodwin on March 09, 1999 at 01:38:59:

I have just added an article written by Jan Gougeon on
mounting chocks to the runner plank (and the plank to the
boat) to the IDNIYRA website.

This article seemed to be very timely after talking to
many sailors at the World Championship. A lot of sailors
seem to have trouble with runner alignment, and I think
the techniques outlined in this article would improve
many boats.

There are a lot of different techniques for aligning
runners, but I agree with Jan that the best starting
point is to bond the chocks to the plank in as close
to perfect alignment as possible. Once this is done
then the only other task is to get the runners to line
up once they are in the chocks. This is no small task,
but the payoff is alignment you can rely on without
having to recheck every time you put runners on the boat.

Check out the article and feel free to make comments
on improvements to these basic techniques. (Come on
Jan - I know you do things a little different now, it
has been 10 years since you wrote this article!)

Iceboat Runner Blades - 3 steps to help you get the most out of yours this season

723

Posted by: Jeff Brown on November 14, 2002 at 12:32:03:

I am interested to hear what others are doing for mounting runner chocks, not alignment methods but actual techniques for epoxys or adhesives.
I am using DN 9" extruded, anodized Super chocks with through bolts and cap plates. All items are new on a new plank, so I do want to set it up right the first time.
I understand how to get the alignment, so please explain the methods for just bolt and plate setting.
I have been using 3M 5200 adhesive for all other parts so far, but due to its elasticity properties I was wondering about more solid fills around oversized bolt holes in the plank.
Do I need the option of chock removal later on or should it be permanent?
I guess removable if I don't get it right......?

Thanks,
Jeff Brown , US 5232

724

Posted by: Bob rast Dn1313 on November 14, 2002 at 13:10:32:

In Reply to: Runner Chock mounting posted by Jeff Brown on November 14, 2002 at 12:32:03:

There seems to be several opinions for mounting and alignment. The first simply Glue them on with west epoxy and some filler with the best alignment you can get and shim runners. I have done this in the past and used a dial indicator for alignment before the glue sets. The chocks can be removed by hitting sharply with a block of wood and a hammer or another DN.
I am trying the loose chock method and aligning each set of runners on the boat under weight on the ice .I glued 100 grit Drywall sand paper to the chock using 3m spray contact cement. this gives the chock some grip when tightened down. I don’t use the Sarns chocks and just have a plate under the 3 bolts above the runner .

725

Posted by: Jane on November 14, 2002 at 18:19:31:

In Reply to: Runner Chock mounting posted by Jeff Brown on November 14, 2002 at 12:32:03:

To break the bond between the aluminum chock and the epoxy, all you have to do is heat the chock with a heat gun. It will fall right off.
I always have the holes through the plank well oversize for the bolts. Then fill the holes with epoxy w/filler. I always put vaseline on the bolts when I put them into the epoxy filled holes. Then the bolts can merely be turned to remove because the epoxy does not bond to the vaseline.

Yes, it is worthwhile being able to remove the chocks. The chocks can always be used on another plank, should you have need to build another plank.

726

Posted by: David Wilkins on November 14, 2002 at 19:26:56:

In Reply to: Runner Chock mounting posted by Jeff Brown on November 14, 2002 at 12:32:03:

Jeff,

I have tried 5200 on chocks. I first waxed the chocks and bolts and installed them in thickened epoxy as close to perfect as possible. The next day removed bolts and broke chocks free. Washed bolts/chocks with acetone and reinstalled with 5200. (This is good for winches etc. on water boats)
But I don't do this anymore. With a dial indicator and some load, I was able to measure some forced misalignment. Another plank I had with just epoxy bonded chocks showed less misalignment.
So, just use epoxy. But, be sure to grind off all anodizing and dimple and roughen the aluminum face with a drill bit. Jane's gottit..easy as pie to remove later with a heat gun.

David Wilkins DN 5065

Which end forward?

827

Posted by: Geoff Sobering on November 13, 2003 at 15:18:56:

I was just installing a brand new set of Sarns chocks on a new plank, and I noticed something "strange". If you look at either end of the slot in the chock where the runner is inserted, one end is cut off square across the extrusion (with some minor rounding), but on the other end there is an angled flat area milled away.

A cross-section through the piece of metal joining the two sides of the chock looks like this:

|XXXXXXXXXX|
|----------/

My question is: does the angled piece face forward or aft? I can think of reasons for both directions. I'm guessing more likely aft, so the runner body contacts a larger area when it drops down as the boat hikes.

Sorry for the terrible description of the geometry, I hope it's clear what I'm trying to ask.

Cheers,

Geoff S.
US-5156

828

Posted by: Paul Goodwin on November 17, 2003 at 07:42:15:

In Reply to: Sarns chocks: which end forward? posted by Geoff Sobering on November 13, 2003 at 15:18:56:

Geoff,

When an iceboat hikes, the leeward runner stays in contact
with the ice, and the nose of the leeward runner is lifted
relative to the plank. The relief angle on the chock should
face forward so that the runner body doesn't come into contact
with the chock at extreme hiking angles. The front of the
Sarn's steering chock is cut away for the same reason.

As an aside, I recommend tightening the runner pivot bolt just
enough so that when the runner lifts off the ice during a hike
the runner nose doesn't drop. This way you minimize contact
between weather runner and the ice, thus reducing friction and
eliminating the annoying "ting-ting-ting" of the weather
runner bouncing on the ice during a shallow controlled hike.

Paul Goodwin - US46

Alignment of Chocks

842

Posted by: Geoff Sobering on January 26, 2004 at 15:53:29:

I have the need to look at the straightness of some runner edges, as well as squaring up a set of old "L" runner alignment jigs. I tried using a quick-and-dirty jig with a cheap laser pointer I had lying around the house, and it didn't work very well. Before I go to the effort of building a nice mount for one or the other device (laser or scope), I was wondering what people have found the best type of each is (and hopefully the approx. cost).

For example, in a scope I assume there is a range of powers and diameters that people have found to be useful. I have no idea what parameters are used to specify laser desirability.

Cheers,

Geoff S.
US-5156

843

Posted by: BVob RastDN1313 on January 27, 2004 at 08:27:08:

In Reply to: Optical alignment: scope and laser specifics? posted by Geoff Sobering on January 26, 2004 at 15:53:29:

I use a old Weaver 1.5 power scope that I removed from a rifle. Not enough power for hunting but good for alignment. Might be hard to find or too expensive. You can pick up a 22 rifle scope at Kmart or Wallmart for 20 or 30 bucks probably a 3x power would be sufficient.You dont need a lot of magnification as you are only sighting 10 feet or so away. Also look for a Mount that you can add V blocks to.There are different mounts available. Mine is a oval that clipped on the side of the reciever. I made blocks that would fit out of some ash.

844

Posted by: Paul Goodwin on January 29, 2004 at 09:30:16:

In Reply to: Optical alignment: scope and laser specifics? posted by Geoff Sobering on January 26, 2004 at 15:53:29:

Hi Geoff,

Remember your suggestion for a superior laser alignment rig???

Here is a link to your post with drawing:
http://cerebus.winsite.com/laser/DNboard/mesgEuro/374.html

Well, I built one using a laser sight I bought at Dunham's
sport store in Detroit. The laser sight cost $30, and luckily
I have the machining capability to do the rest. I bought some
disposable dental mirrors for $0.69 each, removed the mirrors,
and split them in half for a final mirror cost of 35cents.
These are second surface mirrors, but work fine for this
application. Any beam spreading from the two surfaces is in
the vertical plane and doesn't affect the accuracy of the tool.

I've been using the rig, and it works very well. I haven't been
saying much about it yet because I'm having trouble figuring out
how to describe it's use to someone that doesn't already know how
to sharpen runners and check for straightness by eye. The laser
rig seems best for getting the last little bit of straightness
after the runner is already pretty good.

I have shown my device to several people at the Worlds, and it
seemed to draw a fair amount of interest. I'll take some
pictures and post them for all to see. The pictures don't
really provide any more insight than Geoff's drawing, other
than demonstrating my ability to build a prototype from a
good drawing.

It's also a very useful tool for runner alignment,
particularly with my rather unconventional method
(described in detail previously):
http://cerebus.winsite.com/laser/DNboard/mesgEuro/355.html

845

Posted by: Geoff Sobering on January 29, 2004 at 11:05:11:

In Reply to: Re: Optical alignment: scope and laser specifics? posted by Paul Goodwin on January 29, 2004 at 09:30:16:

> Remember your suggestion for a superior laser alignment rig???

Yup... My memory is pretty bad, but luckly not (yet) that bad ;-)

This was really a follow-up question to get more understanding of the specifics about the Lasers (and scopes) that people are using so I can make one myself. My inital experience with my cheap laser pointer showed me that I needed something different, and I thought that while I was at it I would also find out what kind of scopes people were using.

I'm looking forward to seeing the photos of your right-angle rig.

I'm actually curious about comparing the scope and laser techniques. From both a human-factors perspective (see below), as well as to have two different techniques (three with the angles) in my toolbox for evaluating alignment and straightness (in the end, really just pure curiosity...).

For example, one possible advantage of using a scope over a laser is that for finding small local wiggles, your hand and eye are both at the runner, rather than looking at small changes in position of a small spot on the wall 10-20 feet away (I'll post anther note right away with a suggestion on improving that, BTW).

846

Posted by: Bob Gray on January 29, 2004 at 20:17:23:

In Reply to: Optical alignment: scope and laser specifics? posted by Geoff Sobering on January 26, 2004 at 15:53:29:

This is an article I submitted to "Runner Tracks" for a future issue. Some of you might be interested in it now. There is a drawing that goes along with the article that I couldn't get the website to accept, but it's important so I'll try to describe it. It's a fixture to mount a .22 scope on. It's a pece of wood 6" long, 3" high and about 1/2" thick. The scope mounts on top and hot glued perpenticular to the bottom edge near the ends are two pieces of 3/8" wooden dowel about 3/4" long (they are hot glued on so they can easily be replaced). Using the scope as described in the article, you can get an accuracy of .003" or less.

SHIMMING RUNNERS

If you have more then one set of runners, you?ll have to shim them or realign your chocks every time you change runners. I have an easy way to shim runners using a rifle scope and a spare chock (you can use one from your plank if they aren?t epoxied on). The first thing you have to do is make a fixture for your scope. The drawing below is for the one I use.

You can use any rifle scope, but a .22 cal scope is far cheaper (a decent one can be gotten for under $25) and is easy to attach since they have a built in clamping mount.
The following is the procedure I use:

1. Take your chock and mount it on a piece of 2x6.
2. Clamp the 2x6 to a sturdy surface such as a porch railing.
3. Next make a target with a vertical and horizontal crosshair and place it about 50ft in front of the chock.
4. Take a runner and mount it in the chock. Make sure you only tighten the runner bolt as tight as you would when sailing.
5. Line up the center of the dowels on the fixture with the runners edge and press down. Use the notches made as the guides.
6. Roughly aim the runner at the target. Place the scope directly over the runner bolt hole. Rotate the chock until the vertical line is lined up perfectly with the cross hair in the scope (the horizontal line will aid in keeping the scope exactly vertical). Clamp the 2x6 down so it won?t move.

7. Remove the runner and mount the other one from the set in the chock. Use the scope to see how it lines up compared to its mate. Using shim tape on what will be the inboard side of the runner, shim it until it lines up perfectly on the vertical line. You now have a set of parallel runners.
8. Do this with each set of runners you have. Now you?ll be able to change runners without having to align your chocks.

You can make your own shim tape. Buy light weight fiber glass from a hobby shop, saturate it with superglue, squeegee out the excess, spray it with an accelerator like Insta-Set and cut the sheet into strips. The strips can be superglued on the runners. If they are too thick, just sand them to the proper thickness.

The scope and fixture has another use. I use mine to check the trueness of a runner?s edge when sharpening. Just slide it down the runner?s edge to see if there are any lateral deviations.

Using a rifle scope to shim runners isn?t as high tech or as much fun as a laser, but it?s cheaper, easier to set up and works quite well.

BOB GRAY US 4654

860

Posted by: Geoff Sobering on February 28, 2004 at 23:55:39:

In Reply to: Re: Optical alignment: scope and laser specifics? posted by Bob Gray on January 29, 2004 at 20:17:23:

Here's the mount I built along the lines of Bob's description.

I got the rifle-scope from Gander Mountain for $10. The dovetail clamps attach to a thin piece of steel which was ground down to fit. The steel is then hot-glued to the hardboard baseplate. Two dowels are hold-glued to the baseplate. It took me less than 1/2 hour to put together.

Photos are at:
http://iceboating.net/node/view/526
http://iceboating.net/node/view/527

Cheers,

Geoff S.
US-5156

846

Posted by: Geoff Sobering on January 29, 2004 at 12:03:25:

As I mentioned in another thread, I'm concerned about the ability to track small changes to a laser pointer spot on a wall across the shop (esp. when trying to straighten runners).

There is a simple way to improve things two-fold:
1) Double the effective distance between the runner and the spot.
2) Put the spot close to the runner (and the operator's eye).

First a quick re-cap of the technique we're discusing: the idea is to mount a laser to the runner's edge and project the beam across the shop so that small changes in the edge are magnified in the motion of the laser spot.

In optics, it's common to use mirrors to fold the path of a light beam (ex. telephoto mirror lenses). In this case, I thnink replacing the screen on the far end of the shop with a mirror and use a frosted screen (a piece of paper?) near the runner to project the spot onto would improve things.

http://www.mailbag.com/users/sobering/PathFolding.png

The mirror on the wall wouldn't have to be very large (about the size the that the spot displacement), or very high quality (probably a cheap dime-store item).

Thoughts?

847

Posted by: Paul Goodwin on January 29, 2004 at 14:03:22:

In Reply to: Improvement for laser alignment of runners (?) posted by Geoff Sobering on January 29, 2004 at 12:03:25:

As a reference, I've found that pointing to a line 30 feet
away provides all the sensitivity that I require, and I ignore
deviations of less than I can easily see (1/8" or so).

Also, when using the laser for alignment (or dial indicator
rigs for that matter) some people tend to get too critical.
While sailing the runners move around a lot, so the idea of
worrying about less than 0.010" of misalignment between the
front and rear of the runners is adding uneeded stress to
boat setup.

By the way, 0.005" of misalignment (1/2 of the 0.010" total
misalignment) will provide approximately 1/16" deviation at
30 feet using a laser.

855

Posted by: P. Ashley on February 07, 2004 at 01:17:45:

In Reply to: Improvement for laser alignment of runners (?) posted by Geoff Sobering on January 29, 2004 at 12:03:25:

Mirrors seem to be one of the problems related to the "decay" of the beam intensity when multiple reflections are used to understand inaccuracies of runner edge alignment or runner perpendicular/alignment on a compressed plank. I can get a maximum useful reflection of (5) passes from plate to plate. The mirrors had a small 1/4 inch area in the center of each where the film was removed. Since the image of the laser had to pass through each glass to get to the silvered surface, (5) passes meant a path of 72 feet and an effective thickness of 2 inches of glass. I used tracing paper to show the image starting at the first reflection and then slowly drawing the paper in the direction of the reflections.
Several hours of "playing" with shims, clothespins, clamps and rubber bands and even magnets led me back to the idea that a telescopic sight is probably the simplest tool to use and can have adapters for most of our needs.
I still think of the alignment systems used for cars and those hanging devices with the mirrors inside.
Front silvered mirrors would get rid of the "decay" problem, and getting a machined device with a pendulum mirror system to keep away from operator inaccuracies while moving the device along the ice contacting edge would go a long way toward a "device". Shooting the beam from the runner edge installed in the permanently installed chock in the shop forward to a front silvered mirror and back to tracing paper allows you to pencil in any grid you may want on the paper showing the wandering of the image. [getting real fancy - use photographic paper and develop the path of the image] The gravity pendulum would offset the shape of the blade or the levelness of its installation in the chock. Watchmaker gem stones for contact points on the runner edge in the "device" at a spacing chosen by the designer (1 inch?)
Enough! Back to my scope!!!
But - have you ever balanced two forks with a quarter on the edge of a glass? Have you watched a unicyclist on a tightrope? Slide a laser with fishing weights along your runner edge?
Wonderful sport - so much to think about - such a simple craft.
Happy dreaming to all,
Pete

Sails

Battens

849

Posted by: Doug Gaudet on January 30, 2004 at 14:56:38:

I'm making battens with small slivers of wood, tapered to the front (in thickness) and laminating glass on both sides.
I read Think Ice and the author shows a chart with light med, and high wind battens and how to gauge them. He says stand them on their front end and press anywhere from 3 1/2 lbs to 5 lbs to get the taper to start to deflect. Compared to the glass battens I bought "over the counter" - not with the sail, it seems soft. What I did was stand the battens on my stairs and put a 5 lb bags of sugar on then to see if they would deflect. Is this the going philosphy. I have an old wooden mast and another aluminum mast.

854

osted by: Paul Goodwin on February 06, 2004 at 08:31:19:

In Reply to: Battens-size? posted by Doug Gaudet on January 30, 2004 at 14:56:38:

Doug,

This is still the "preferred" method for measuring battens, and
the values have not really changed much over the years.

The standard battens delivered in US sails are generally 3, 4,
and 5 lb., measured with a simple scale. some of the European
sails, particularly the speed sails, have significantly stiffer
battens (up to 11 lb for the top batten).

I don't think putting a 5lb bag of sugar on the batten will
yeild useful information about batten stiffness. A bathroom
scale works quite well, although a more sensitive scale (like
a postage scale) works better. You simply put the tapered end
on the scale on the scale, and push down until the batten bends.
You'll find that once it starts to bend the force stays pretty
constant.

Tell-Tale Streamers

340

Posted by: GeoffS on July 12, 2003 at 23:01:39:

I found an interesting note about tell-tales on wing-mast sailing rigs:
http://www.ahpc.com.au/wingmastrig.html

The author suggests putting a pair a tell-tales near the leading edge of the sail in order to detect the separated flow on the leeward side when the mast is over-rotated.
I was wondering if anyone has tried this in the DN (or any other iceboat)?
I'm not particularly good at visualizing the correct mast rotation from the cockpit, so I'd really benefit from some kind of aid while I'm figuring out the finer points.

368

Posted by: Ken Smith on November 19, 2003 at 00:00:55:

In Reply to: Far-forward tell-tales and mast rotation posted by GeoffS on July 12, 2003 at 23:01:39:

Geoff:

No ever picked up on your question. This is because the tell tales are less important on an fast moving iceboat than a sluggard softwater boat. [This should get some responses!] And less worthy of discussion.

I go with two or theree tell tales at various heights a half meter behind the mast midway between battens and a tell tale on the end of each batten. But except for accelerating in light wind, I do not remember focusing much on them. I do look at the one nearest the top batten the most. When I am starting or in light air.

At speed in any decent wind, the sail has way too much power, and drag reduction is the key to speed. Most of the drag on the boat is from the rig and sail. This is one reason a bendy mast is fast. It allows all the sail to accelerate, then pulls the bottom flat and opens the leech up high so the top of the sail is twisted off and streamlined with the breeze and not developing drag. So tell tales only tell anything when you are going slow.

I have seen tell tales all over the sail. They let you know if the seperation bubble behind the mast is too big (get mast de-rotated), if the leech is too hooked (of like a blast, then everyone else accelerates past you), the sail too full (ditto)... but a feel for the boat and judging by the speed around you tell just as much.

Listen to Ron's description of accccelerating then changing gears...Play the mast not the tell tales.

IMHO. From the back of the Gold fleet.

Ken Smith

369

Posted by: Geoff S. on November 19, 2003 at 22:09:34:

In Reply to: Re: Far-forward tell-tales and mast rotation posted by Ken Smith on November 19, 2003 at 00:00:55:

> This is because the tell tales are less important on an fast moving
> iceboat than a sluggard softwater boat.

Wow! What a "troll"! I can't wait to see this!

Seriously, thanks for the info.

My tell-tale useage pretty much matches you pattern. I usually don't have much attention/cognition to devote to tell-tales while racing, so simple is the key...

I'll check the upper leach tell-tale to make sure the leach isn't closed (only a problem in light air).

But, probably my most frequent tell-tale use is down wind. I'll use a tell-tale near the center of the sail to make sure I'm not sailing too low and stalling the sail. Normally that's not a problem, but it's the first thing I check if I think I'm going too slow (usually simultaneous with heading up). It also warns me to watch out for a big surge as I head up and flow reattaches!

However, what I was interested in is specifically using a set of "Gentry tufts" just aft of the mast to make sure the air is flowing nicely over the forward/leeward side of the sail. This would only be something to pay attention to during tuning, not as a sailing aid.

The reason for my interest is that most of the lift from a foil is generated in the forward 25% (the rest of the foil/sail is really just there to slow the flow down to free-stream velocity). With a wing-mast/soft-sail combination, it's possible to over-rotate the mast and cause the flow to "trip" at the discontinuity between the trailing edge of the mast and leading edge of the cloth. This causes a "separation bubble" (like you mention) to form on the forward part of the sail. Usually the flow re-attaches within a foot or so, but there's a tremendous amount of power lost (not to mention, additional drag). Under-rotation of the mast can cause the same effect. The air can't flow into the hollow between the point of maximum width on the mast and where the sail starts to curve out. Strangly enough, under-rotation isn't particularly low-drag (at least from a 2D foil-profile pespective). The optimum for both lift and drag appears to be when the curve of the mast and the curve of the sail match. You reduce power and drag by reducing the angle-of-attack (sail higher or deeper, as appropriate).

This sensitivity effect is, BTW, why Frank Bethwaite started using wing-masts with a cut-off trailing edge:
http://www.bethwaite.com/bethwaite/articles/story__wnksnwtr__6392.html

Cheers,

Geoff S.

P.S. the note on rotation isn't 100% true. Over-rotating the mast is a high-lift/high-drag mode that works well at high angles of attack (near stall). Useful for getting started "off the line", or perhaps after a bad tack, etc. Very useful in softwater boats which are almost always power-starved. Too bad we don't have better mast-rotation controls (or not, I don't think I could manage another control myslef...)

Mast Rotation

270

Posted by: Paul Goodwin on November 20, 2003 at 08:44:10:

In Reply to: Re: Far-forward tell-tales and mast rotation posted by Geoff S. on November 19, 2003 at 22:09:34:

There is more to mast rotation than just finding the point of
minimum drag for a 2-D cross section of the foil.

I don't pretend to fully understand mast/sail interaction, but
it is entertaining to talk to Jan Gougeon about this subject.
Bottom line (as I understand it) for the DN: at high speed in
decent winds, it's hard to de-rotate the mast too much. The mast
on a DN wants to over-rotate, and our only control over this
is to pull back on the boom. Once the DN has reached a high
speed, the sail has too much twist and generates a lot of drag.
De-rotating the mast aligns the stiff fore-and-aft line of the
mast with the sail, reducing mast tip deflection and tightening
the upper part of the leech. This provides lower drag and better
pointing ability, allowing the boat to go into "warp" (another
Jan-ism). During this transition, you can point the boat higher
(perhaps by 5 degrees or so) without losing speed.

Properly set up, as the DN accelerates the mast will "pop out" and
start to bend. This allows the boat to shift gears and accelerate
further since it flattens the sail. At this point the rear
mainsheet blocks should be almost touching. Eventually the boat
will reach a top speed and hit the wall. For many sailors this
is the fastest they will go, not realizing there is yet another
gear.

If you look at a boat at the top of the fleet you'll likely find
that the mainsheet blocks are sitting at a 45 degree angle (or
thereabouts) when the blocks are almost touching. Pulling the
mainsheet in further will pull the boom back, and the blocks
will nest together. It's this final rearward boom movement of
2"-4" that de-rotates the mast and allows the boat to shift gears
and go into warp.

Perhaps part of what makes de-rotation work is the smoother
transition on the lee side of the mast and sail, but I haven't
noticed any change in telltales along the front part of the sail.

Rigging

Sources for Hardware

619

Posted by: Roger Livingston on February 06, 2002 at 07:34:56:

I talked to Sarns yesterday and they are under new ownership at a new location. The telephone number remains 810-463-4269. The new address is 22931 Industrial Drive West, St. Clair Shores, MI 48080

I am glad to see someone take over the business. It's good for our sport to have a single source for all the hardware necessary to build a DN. I wish them well.

669

Posted by: Charlie on April 03, 2002 at 09:14:37:

In Reply to: Sarns posted by Roger Livingston on February 06, 2002 at 07:34:56:

Sarns new web address is www.sarnshardware.com -- Get ready for sticker price schock !

Rigging a Hull (Putting on hardware)

746

Posted by: Dave Rancilio on January 01, 2003 at 21:30:55:

In Reply to: Has anyone saved a "kissed" (kinked) FG mast? posted by Brian Lamb on December 22, 2002 at 19:19:47:

I have just started sailing this year and have been using my fathers old boat. He passed away 5 years ago and I have finally gotten around to sailing his old boat and I cant believe how much fun it is. I have been out three times already this year. The boat was in the rafters of the basement for about 20 years. Today while sailing the hull had a major failure. The mast drove itself through down through the hull and destroyed the hull. Luckly I have another hull that my Dad was building but never finished. It has no hardware on it but the holes for the steering are in the hull. Most of the rigging seems to be pretty straight foreward as I will be transfering the hardware from the broken hull to the new one as soon as I paint it. What I need some advice on is how to get the plank mounted correctly and where to mount the mast ball as the hulls are not exactly the same.

747

Posted by: Jeff Soderholm on January 02, 2003 at 09:20:42:

In Reply to: Rigging hull posted by Dave Rancilio on January 01, 2003 at 21:30:55:

Dave,

Just a note on the failure you mention. Failures of that nature can occur when the bob stay is not properly rigged or installed. Many remove the bob stay post for storage and re-install when setting boat up for sailing for at the beggining of the season. You may already be aware of this but if not you should know this can be the cause of hull failure under the mast.

Is the new hull a 'wedge style'? The wedge style has much more width in the rear of the cockpit by the seat back as opposed to the older Sarns style which was narrower overall but it was widest more towards where your knees would be.

Jeff

750

Posted by: Jeff Soderholm on January 02, 2003 at 22:29:13:

In Reply to: Re: Rigging hull posted by Davr Rancilio on January 02, 2003 at 14:49:24:

Dave,

Yes, the wire and bracket are what I was refering to. The newer style set up has a single alum. post the seats in a socket under the hull instead of the traingular bracket your boat has. Also, newer hulls the wire ends just before the plank instead of running the full length which makes it easier to install and remove the plank. I think Bob has touched on what may have been the demise of your boat; old age. Had you removed the bottom skin and checked all the joints and bulkheads you probably would have found the glue was failing and it was just a matter of time without any attention. You should be able to use some of the old hardware but you may want to upgrade some of the older parts like the steering. If the steering chaulk has two cables one attached to each side then you may want to upgrade to the newer single attachment that utilizes an alum. tube instead. with a ball joint on each end.

One thing you really should invest in is a copy of the book 'Think Ice' which is available through the IDNIYRA for $15.00. Best investment you will make in iceboating bar none.

Jeff

749

Posted by: Bob Rast DN1313 on January 02, 2003 at 15:12:04:

In Reply to: Re: Rigging hull posted by Davr Rancilio on January 02, 2003 at 14:49:24:

Most likely the failure of the hull under the mast was due to old age. I helped a friend repair a old DN a while ago. After removing the deck , we found the only thing holding the bulkheads under the mast in the hull were the old brass screws which had deterioted about 50 % and the recorcinol glue was no longer bonded. we reglued with epoxy and redecked. He would probably had a similar failure soon.

Springs on Front Chock

881

Posted by: John on June 21, 2004 at 08:49:13:

Where can I buy a spring that is used on the DN ?
Thanks

883

Posted by: Geoff Sobering on June 25, 2004 at 12:11:58:

In Reply to: Front runner suspension spring posted by John on June 21, 2004 at 08:49:13:

I got one for my first DN at a rural hardware store...
It wasn't tapered, or stainless, but it did the job.

If Sarns won't sell you one (sarnshardware.com), you might try McMaster-Carr (mcmaster.com).

Also, don't forget to put some kind of bumper or spring on the top of the steering post to absorb the shock when the post extends fully. I understand that the elastomer doughnuts from mountain-bike suspensions are a good choice (I have a hunk of rubber wrapped around the post on my boat...).

Plank to Hull

833

Posted by: George on December 10, 2003 at 21:36:11:

DN 5250 is just about complete. A question remains:

I am using the internal stud plate and plank plate set. Do I drill the 1" holes to accommodate the nuts all the way through or parially through. If partial, should I reinforce with thickend epoxy and a washer or what?

834

Posted by: Bob rast DN1313 on December 10, 2003 at 22:23:03:

In Reply to: Plank bolt clearance holes. posted by George on December 10, 2003 at 21:36:11:

I have the internal plates and just cut a slot for acces to studs. Ive seen others that have drilled individual holes. I guess its your preferenc.The nuts go right down to the plate. You want the stud to come off the plank or plates to come off the hull to prevent further damage to the hull .

Bobstay

873

Posted by: dave on April 01, 2004 at 18:40:29:

Just Finishing putting a hull back together that the side blew out in the area of the mast step/bob stay it was suggested that the failure occured because the bob stay was unadjustable and likely not tight enough cable has been replaced with adjustable cable from sarns question is how tight should it be. set it with a torque wrench ?? how tight or?? bob stay cable is full length

874

Posted by: Geoff Sobering - US-5156 on April 02, 2004 at 11:28:17:

In Reply to: Bob Stay Cable Tension posted by dave on April 01, 2004 at 18:40:29:

I set up bobstay length so that it takes some effort to "pop" it over the top of the bobstay post and into the grove.

This is for a "short" bobstay and standard Sarns bobstay post/socket combo, but I seem to remember that it was basically the same on my previous Sarns-style hull with full length bobstay.

Cheers,

Geoff S.

Blocks (pulleys)

432

Posted by: Pete Ashley on November 24, 1999 at 02:13:47:

A very strong word of caution for those of you who have NOT
tried the 2nd. ratchet block yet. In strong gusty wind situations the mainsheet may NOT release when you let go or ease the sheet. I found out the hard way and left my boat at high speed. The additional friction and the shape of your sheet play an important part. Test BEFORE racing!
Read Bob Dill's report on block friction and think it through IN REVERSE.

835

Posted by: Scott Crothers on December 12, 2003 at 15:39:25:

"Black Ice" (my DN) is ready to go, (it can be seen @ www.iceboating.net) but I'm looking into upgrading my 40-year-old, plain, stainless sheet blocks with a newer style system. Looking at the 2003 Layline catalog, there are (Harken)16mm, 29mm, 40mm, 57mm, 75mm etc. in a variety of Airblocks, Carbo Blocks, Ratchamatics and Hexaratchets. Then track options appear to mount them on, including Ronstan and Schaefer to name just two. What size blocks are commonly being used and where? I've seen suggestions for 2" @ rear, dual 3" ratchets at front. Would that be the 40mm Carbo's @ 1-9/16" or 57mm @ 2-1/4"?
I would also welcome suggestions on size and type of line to match my new components. Braiding takes time, but I think I can handle it, especially since Indiana is still waiting on ice.
Any and all suggestions are welcome.
Thanks,
Scott

836

Posted by: Geoff Sobering on December 13, 2003 at 01:16:15:

In Reply to: Sheet Block Upgrade Ideas posted by Scott Crothers on December 12, 2003 at 15:39:25:

IMO, the Carbo Airblocks are the *only* way to go for DN-sized boats. The Tie-Lite's are particularly cool, light and versatile.

The one exception is the ratchet block; you need the most holding power you can get! Harken's Hexaratchet II+2 or the Frederiksen Ultimate are the only one's I know of that really work. I don't have a Frederiksen, but I've heard it doesn't work well with a chain-stitch mainsheet (i.e. it works *too* well, and never lets go).

On my current boat I'm using a Hexaratchet II+2 on the tiller-post, a 57mm Carbo Tie-Lite on the front of the boom, and older Big-Bullet blocks on the boom and deck. On my previous boat, I had a similar rig, but with 40mm Carbo blocks at the back; tie-lites on the boom, and shackles on the deck. Both configurations work pretty well, although I never used a braided mainsheet with the 40mm carbos.

Which brings up my question for this thread: what is the smallest block that the chain-stitch (aka "braided") mainsheet will go through? More specifically, can I get away with 29mm carbos?

836

Posted by: Bob rast Dn1313 on December 13, 2003 at 08:34:46:

In Reply to: Re: Sheet Block Upgrade Ideas posted by Geoff Sobering on December 13, 2003 at 01:16:15:

I have the older Harken Bullet blocks about 1 7/8 diameter . There is a metal tab on the fore and aft of the block which you can cut or break off as it isnt needed. You can then remove the plastic material and the braided line will go through just fine. Want to do this on the front boom pulley near the mast and maybe the first rear pulley. Of course you will void any warranty but so what.

838

Posted by: John Jombock , DN1513 on December 13, 2003 at 15:40:37:

In Reply to: Sheet Block Upgrade Ideas posted by Scott Crothers on December 12, 2003 at 15:39:25:

I think a Harken 009 Hexaratchet (3") on the steering post and
Harken Dinghy Blocks (1-3/4")on the boom and deck are a good
straight-forward choice . But , many other choices would also do
the job .

I've never been convinced that the "daisy chain"/"braided" mainsheet
is a super idea . I like a fuzzy-finish 3/8" Dacron braided sheet
with 9 ft of 3/16" Dacron braid on the aft end . A suitable tapered
transition is required , but that's not a difficult task .

I've been selling Harken blocks at 20% discount to DN sailors for
many years . I would be happy to discuss block selection with you
at your convenience . Good sailing this winter !

John Jombock
136 Applewood Lane
Slippery Rock , PA 16057
724.794.4425 or jjblueskies@aol.com

289

Posted by: Jane Pegel on January 20, 2003 at 20:26:15:

I use a Fredrickson ratchet block on my DN. It is more efficient than the Harken ratchet block and I find that with my tapered mainsheet the Fredrickson block is very nice indeed. HOWEVER, if you are using a custom braided mainsheet, like the Composite Concepts mainsheet, the Fredrickson ratchet is too efficient and you may not be able to ease the sheet when required. I recommend that you use a Harken ratchet if you are using this type of mainsheet.

regards,
Jane Pegel

290

Posted by: Gary on January 22, 2003 at 13:31:53:

In Reply to: Ratchet block safety warning posted by Jane Pegel on January 20, 2003 at 20:26:15:

Great point Jane. The Frederickson is the best there is for standard and tapered sheets. But, the holes might bind/hold on to the braid when releasing. Have you tried the Ronstan Ratchet? They have greater clearence between the cheeks than the Harken and allow a larger diamiter sheet and/or the braid to be released with less friction.
Gary

Main Sheet

709

Posted by: Geoff Sobering on October 24, 2002 at 08:57:08:

I need to replace the mainsheet on my DN because the cover is a bit slippery and it's getting hard to hold onto. My current mainsheet is tapered by putting a cover over the tail end of a length of 3/16" StaSet-X (the StaSet runs the entire length of the sheet; the cover ends right about at the front of boom when I'm sheeted in all the way). I was thinking of changing the rope on the narrow end of the taper to something like 1/8" or 3/16" Spectra or Vectran with cover in the 5/16" range. I wasn't sure about the best cover material and construction techniques.

Does anybody have suggestions/opinions about what makes the best mainsheet? (esp. cover materials that give good grip).

My fallback position is to buy some of the Marlow "taperable sheet" and use it. The main problem with this material (IMO) is that the 1/4" core on the larger diameter version (3/8" covered) is bit overkill for a DN mainsheet, and the 1/4" covered diameter on the smaller diameter version is a bit too small.

Cheers,

Geoff Sobering
US 5156

712

Posted by: Paul Goodwin on October 30, 2002 at 15:49:39:

In Reply to: Re: Mainsheet suggestions? posted by Geoff Sobering on October 30, 2002 at 14:02:09:

I can't remember the actual lengths involved, but I do know the
philosophy behind setting the lengths.

1) When you are fully sheeted in (completely 2-blocked in the
back and the halyard at it's lowest position), you want the
braided section to "just" be engaged in the ratchet block with
the thin line exposed below the boom.

2) When you are fully sheeted out (stopping), you want the boom
as close to centerline as you are comfortable with.

The reason for "1)" is exactly what you mentioned. If the 3/16"
line gets into the ratchet block (and of course this happens
under maximum load), then there is no grip and the ratchet block
can't do it's job.

The reasoning behind "2)" is less obvious. If you lose your grip
on the mainsheet, then it runs out and you have to haul it back
in, losing precious time and distance against your competitors.
So you want to keep it as short as possible. If you get it too
short, then things get pretty exciting in heavy air when you want
to slow down. For me, I like it when things are exciting, and
who wants to slow down anyway?!?!?!?

Keep in mind that for a short mainsheet to be safe, you need some
way to release the sheet when the boat is parked. The slotted
tube system on the back deck solves this nicely. Another thing
nice about this (slotted tube) system, you can release just
the rearmost deck block when cruising, providing an extra length of
mainsheet -- useful for going to and from the course in heavy air.

As far as the mainsheet going out through the blocks, this can be
a bit of a problem. Harken blocks have pretty wide cheeks, and
even the smaller blocks have enough room. There is a little bit
of binding, but it's not really a problem while racing if you have
the lengths set up properly. It's more of a problem when you
want the boom all the way out (coming to a stop), but pushing on
the boom will get it to move. If all else fails, reach back and
pull the sheet through the blocks -- easier than it sounds, but
frightening in a panic.

713

Posted by: Paul Goodwin on October 31, 2002 at 18:18:00:

In Reply to: Re: Mainsheet suggestions? posted by Geoff Sobering on October 30, 2002 at 14:02:09:

As far as the tying the knots, I can tell you how to get started.

The first knot is a simple overhand slip knot, with the loop
pulled through in the direction you want the braiding to go.
Then you pull a new loop through the first loop. Snug the first
knot up to take out the slack, and continue braiding till you get
the desired length of braid. You finish the braid by passing the
end of the line through the last loop.

Because of the fairly course braiding, the line tends to "carch"
in a Harken Hexeratchet, providing a little extra holding power.
However, this also makes the sheet pay out in steps, each step
being equal to the distance between the knots in the braid.
If you don't snug the knots up, I don't think the sheet works
as well since it pays out in bigger steps.

715

Posted by: Paul Goodwin on November 04, 2002 at 08:08:42:

In Reply to: Re: Mainsheet suggestions? posted by Paul Goodwin on October 30, 2002 at 15:49:39:

I was talking to somebody at a swap meet over the weekend, and
they asked me about releasing one of the rear mainsheet blocks
while I was cruising. He was very curious about how you reach
back and pull the pin to release the block while sailing!!!

Amazing the difference between what people read and what I mean
to write. I don't pull the pin out WHILE cruising around, I pull
it out while the boat is stationary. I typically do this when I
have a boat load of gear and I need to get out to the course, and
it's blowing 25 mph. When my boat is parked and it's that windy,
I always have the deck blocks released so the sail can't fill if
there is a wind shift. When it's time to sail out to the course,
I'll just use the forward deck block and leave the rear block
loose. This gives me lots of extra mainsheet, and I'm less likely
to over-sheet since I have two parts less purchase.

718

Posted by: Geoff Sobering on November 06, 2002 at 00:29:16:

In Reply to: Re: Mainsheet suggestions? posted by Geoff Sobering on November 05, 2002 at 13:44:00:

I took a couple of photos of the braided/chain-stitch DN mainsheet that Paul recommended. They're posted two places:

http://sobering.terracom.net/iceboating/BraidedDnMainsheet/
http://groups.yahoo.com/group/IceBoating/files/DN%20Braided%20Mainsheet/

The latter is only available to those who are members of the Yahoo! "Iceboating" group.

I'd appreciate if those of you who know this technique better than I could check the photos to make sure I'm illustrating the right way to make this sheet.

Cheers,

Geoff S.
US 5156

719

Posted by: Pete Ashley on November 07, 2002 at 02:12:13:

In Reply to: Re: Mainsheet suggestions? posted by Geoff Sobering on November 06, 2002 at 00:29:16:

Geoff,
Found your pictures very instructive. Thanks! Your final picture of
all the knots in a row seem tighter than those I have been using. Some
may find these to "catch" on the ratchet block as Paul mentioned. If
the line is thin enough, your knot spacing may work just fine. I spaced mine out to "ease" their passage through the Harken block.
Now to the real reason for my message. I wish to let you all know
the real "SAFETY" behind such a mainsheet. My bare line before starting the knots was about 42 feet. Lets say someone goes through the thin ice and three sailors stop to help rescue. 3 x 42 = 126 ft. of instant rescue line available!!! Just by releasing the last knot and a quick pull --- Zziipppp. Actually I can't take credit for this as Ron Sherry was the one who showed me how to make his sheet and the rescue feature disguised within.
If your knots "creep" over time - just Zip it open and re-knot.
Goeff - Did you plan the backdrop to your pictures?? If I'm not mistaken that may be a chain link stich in that knitted garment?

721

Posted by: Paul Goodwin on November 07, 2002 at 17:34:10:

In Reply to: Re: Mainsheet suggestions? posted by Pete Ashley on November 07, 2002 at 02:12:13:

Pete,

I think the knots that Geoff used are correct, and I would make
them that tight. The "catching" that I referred to is a good
thing, I didn't mean to imply that it was a flaw in any way.
I never have a problem easing the mainsheet while sailing, even
in light air. For me, it's forms a symbiotic relationship with
the Harken Hexaratchet, providing a little extra holding power
when the mainsheet is heavily loaded, and running freely under
light loads.

The only time there is any difficulty with the mainsheet going
out is when the braid gets to the small bullet blocks at the back
of the boom. But the sheet should never be out this far when
racing if it adjusted properly.

722

Posted by: P. Ashley on November 09, 2002 at 23:57:00:

In Reply to: Re: Mainsheet suggestions? posted by Paul Goodwin on November 07, 2002 at 17:34:10:

Paul, I agree that Goeff's pictures are "right on". I mentioned your term "catching" to sort of tie the messages together and also indicate that the length of the loops that are chained together does influence the ease of passage through the hexaratchet, thus one can fine tune the catching somewhat. A "Chain Sinnet", Ashley Book of Knots,pg. 472,was used in the old days of sailing to provide a stout line when only light line was available. A threefold reduction of length with almost a threefold increase in strength. Knot # 2870
I am going to try a cam cleat on the end of my boom so that I can quickly adjust the position of the braid in relation to the hexaratchet. The loose end will pass through the cringle at the outhaul. Magic marker when I get the position correct in the cleat. I tie the other end to my tiller.
Thanks for all your contributions Paul!!! I hope someone is creating a history archive.

[I am! You bought it. :-}]

Shrouds

Shroud lengths

449

Posted by: ken smith on December 15, 1999 at 08:09:03:

In Reply to: Re: Shroud measurement info posted by Frank M on December 11, 1999 at 12:33:03:

Frank:

No one answered yet so here goes:

With the sail and boom on, the halyard set so the sail is at its lowest possible position (the fitting by the eye is in the halyard stop) the following apply: The bottom of the boom blocks should be an inch or so above the top of the deck blocks. The mast should be in its aftermost position. The forestay should be near its longest adjustment. The side stays should be the same length and each near its shortest adjustment. This is as far back as you will ever likely be.

The Sarns adjusters are just long enough to deal with the side stay adjustment range you can expect to need. A staymaster or stay-loc is not quite long enough to allow enough adjustment range. Most have a short pin type adjuster on the forestay with a stay-loc, staymaster or turnbuckle. A stay-loc is a turnbuckle modified with a handle. It has fine threads and can be adjusted under tension without tools.

I have a stay-loc (in its fifteenth year) and a pair of five-hole straps on the forestay. Make sure pins let the end of the forestay move both fore and aft and side to side, or your wire or hardware will fatigue and break.

I made 12" shroud adjusters out of streamlined aircraft tubing for the sides. The sides see light loads compared to the forestay.

Ken Smith
DN 4137

[]-==-[ooooo]-----

450

Posted by: Paul Goodwin on December 17, 1999 at 11:20:27:

In Reply to: Re: Shroud adjusters posted by ken smith on December 15, 1999 at 08:09:03:

hmmmm,

Well, Ken's answer is pretty well thought out (as usual), but
I might add a couple comments. You need a fairly wide range of
adjustment to get the boat set up initially. But after that, the
sailors in my neck of the woods have been using less and less
adjustment. A big difference here has been the development of the
fiberglass mast and sail combination. These have such a wide usable
range, that the rig adjustment isn't as critical as it was with
aluminum masts.

Unfortunatley, many things factor into the correct adjustment,
including plank stiffness, sailor weight, and the sail used. This
makes it difficult for the inexperienced skipper to find the sweet
spot with any particular rig. The good news is, once it's dialed in,
then you shouldn't need a lot adjusment after that. A good thing to
do is to write down a setting that is working well so you can get back
to it easily.

I think it is interesting to note that Ron Sherry has won the last
two World Championships using NO SIDE STAY ADJUSTERS. That's right
... Ron uses fixed length side stays on his boat, and relies only on
mast step position, forestay length, and halyard height for tuning.

I tried this setup at last years Worlds, and there is a lot to be
said for it. It eliminates one of the tuning variables, which makes
it a little easier to get the tuning right. But this step is not
for the faint of heart, and I wouldn't recommend it without trying
the idea out first. Try to get to where you don't have to make any
adjustments to the side stays, then measure them and carefully
duplicate the setup using fixed length stays.

Here is my 2 cents worth of rig tuning tips. Start with the mast
step in the back position. Adjust the forestay so there is 6-8"
between the mainsheet blocks. The side stays should not be sloppy,
and usually with enough tension so you have to pull hard to get the
pin into the tang. If you find that the mast won't bend once the
boat is up to speed, then move the mast step forward, adjusting the
forestay to maintain the same 6-8" between the blocks. The mast
should bend without too much work as the boat picks up speed. The
side stays should not need adjustment using this method.

If your not able to point quite as high as the sailors around you, try tightening the forestay a little to rake the mast forward. Conversely, if you aren't able to pull the mainsheet in all the way at top speed without hiking excessively, then let the forestay out a little to rake the mast back. The boat should be easy to sail at top speed without a lot of hiking, that way the rig is doing the work instead of your arms!!

The halyard height can be used to make quick changes in leech
tension. If you're sitting on the starting line and the wind
velocity increases significantly, drop the halyard down one notch.
If the wind decreases, pull the sail up a notch.

Head Stay

773

Posted by: Jeff Brown on December 16, 2002 at 10:28:47:

What is the race lengths being used for DN extreme rake stays.
I have a Staymaster turnbukle plus a forestay @ 11'-8 1/4".
I measured this dimension from another sailors setup, but I think this is too short. It seems like I have standard upright length setup.
I understand that the rig should set about 20 deg rake from vertical. I can get close to that with this forestay set to the maximum length, but it seems I can't get the boom sheeted in all the way to the deck like I see other DN's under load.(My sail has nearly max. leech length so that is not an issue)
My side stays are fine and nearly to the max length.
This set-up was with the mast foreward and the plank aft.
Something tells me I should have a forestay length of
12'-0" plus the staymaster.
Need advice, please, anyone.

734

Posted by: Ken Smith on December 16, 2002 at 19:07:34:

In Reply to: DN Extreme Rake stay lengths posted by Jeff Brown on December 16, 2002 at 10:28:47:

Sounds too short... but no one can tell you the correct length as it depends on your deck heights, mast ball, and the height and length to the forestay chain plate at the bow. Most have both a stay-master (or Johnson Sta-lock) plus a shroud adjuster, like the Sarns or similar, with 6-9 holes. Add one or more to your rig and it sounds fine. For a small length increase, use a longer shackle of add a two stainless straps like stay length adjusters, but without the extra holes. All these are lots cheaper than a new forestay.

Ken Smith
DN 4137

739

Posted by: Paul Goodwin on December 19, 2002 at 12:26:07:

In Reply to: Re: DN Extreme Rake stay lengths posted by Ken Smith on December 16, 2002 at 19:07:34:

I agree with Ken, a pin adjuster added to the forestay should put
you right in the ballpark. My forestay is 4-1/2" longer than yours,
but the length depends on the stuff you use (hull, mast, plank, sail,
boom, blocks).

Be sure to check the other rigging length messages posted in the
OPEN FORUM, TECHNICAL DISCUSSION section.

Head stay length by other measures

275

Posted by: Jeff Soderholm on November 11, 2002 at 11:26:11:

In Reply to: Forestay length posted by Patrick Zachary on November 11, 2002 at 07:39:17:

I am not sure but I think forestay length can vary depending on the exact location of the hound on your mast and the construction or design of the fore stay attachment point. One thing you can do is check the mast angle with a protractor. I have a dial model from home depot which when held up againest the mast will tell you your mast angle and which can then be compared to other boats in the launch area. I seem to remember around 70 degrees give or take a degree.

276

Posted by: Geoff Sobering on November 11, 2002 at 19:49:53:

In Reply to: Re: Forestay length posted by Jeff Soderholm on November 11, 2002 at 11:26:11:

There are a couple of other ways to measure and compare mast rake:

One way is to hang something like a wrench from your main halyard shackle and use it as a plumb-bob. Measure the horizontal distance between the mast-ball and the halyard. I seem to remember reading somewhere that the mast tip should be about over the middle of the plank. One advantage of this measurement is that it's a pretty easy to do, and the measurement correlates pretty closely with rake (the mast height does affect it...)

The other way is to measure the distance from the mast ball to the forestay at a perpendicular to the foresaty (i.e. the shortest distance from the ball to the wire). This technique was discussed a bit last year, but I couldn't find the thread. I seem to remember there was some posting of "typical" values, but I don't remember much of the details. I haven't looked at the geometry of this measurement, but I believe the correlation between rake and this measurement would involve the foredeck length and hound-height; the latter is petty standard these days (I think?), but the former can vary quite a bit.

Here's a couple of notes that I found about setting up shrouds:
http://cerebus.winsite.com/laser/DNboard/mesgConst/449.html
http://cerebus.winsite.com/laser/DNboard/mesgConst/450.html

277

Posted by: Patrick Zachary on November 12, 2002 at 16:58:20:

In Reply to: Re: Forestay length posted by Geoff Sobering on November 11, 2002 at 19:49:53:

Thanks Geoff & Jeff - I also got a personal reply from Jane Pegal suggesting:

Rig up the boat with the sail up and hoisted to the average height you use. Pul the boom on the sail. Set the forestay so the measurement from the deck at the tail of the hull up to the bottom of the boom is 14 1/2 inches with no trimming on the mainsheet line. With this setting, you want the forestay to be set in the adjuster so that the pin is 60% up from the bottom of the adjuster. This will give you a range to tighten and loosen the forestay as you move the mast step and as you trim the sail.

I was then going to center the mast with a plumb bob from the top sheave and measure shrouds from fitting on mast to the center of the Sarns adjuster on one side and make two shrouds this length (mast would be in last hole (towards stern))

Comments?

283

Posted by: Paul Goodwin on December 19, 2002 at 12:19:12:

In Reply to: Re: Forestay length posted by Patrick Zachary on November 12, 2002 at 16:58:20:

Your approach sounds good. I would recommend using a Staymaster
(or equivalent) on the forestay since forestay length is critical
and small changes go a long way. If you also have a pin adjuster,
then you will have plenty of adjustment range. Personally I use
only a Staymaster on the forestay, and no side stay adjusters.
This has enough range of adjustment if you are already dialed in
with your lengths.

From your first post, it sounds like you are using one of Jeff
Kent's masts (with the T hound). Since I use a Sherry mast, it
is more difficult for me to relate how my boat is set up to yours.

Other things that factor into the equation for stay lengths are
hull profile, sail shape, size of blocks used on the rear, plank
crown, yada yada yada....

All these factors make Jane's suggestion the right approach.
The critical thing is the the height of the boom from the deck
since this controls how much you can pull in the mainsheet.
However, I think a better measure is the distance between the
blocks and the deck, rather than the boom and the deck since
people use diferent size blocks. I start with 6-8 inches of
distance between the bottom of the rear boom block and the deck.
This sounds like a lower boom height than Jane recommends.

Since I sail with the mainsheet all the way in (two-blocked)
most of the time, this 6-8" height controls how far I can sheet
in. For the last three years I have been sailing with fixed
length side stays, and this has worked out well for me. Once
everything is pretty well dialed in I use the following adjustments
to tune for different conditions:

1) If the mast will not "pop-out" (bend) after the boat has
accelerated, and the boat is constantly hiking and pointing too
high and going slow, I will either:
a) Rake the mast rearward (lengthen the forestay), and raise the
sail to maintain the 6-8" boom height.
b) Move the mast base forward, adjust the forestay length to get
the proper side stay tension, and raise the sail to maintain the
6-8" boom height.

2) If the mast bends prematurely (the mast is hanging way out and
the boat is not up to top speed, won't hike, can't point), then I
do the opposite of the steps above.

3) If you use side stay adjusters, then to get:
a) More mast bend, lengthen the side stays
b) Less mast bend, shorten the side stays

4) If the boat is sailing well, but the wind strength suddenly
changes (especially when you are on the starting line), you can
make a minor change in tuning:
a) Wind increases: lower the sail 1" (less leech tension)
b) Wind decreases: raise the sail 1" (more leech tension)

Now, here is why I can get away with only a Staymaster on the
forestay, and no sidestay adjustment. If you shorten the forestay
a little and lower the sail, it rakes the mast forward (less mast
bend), it tightens the sidestays (less mast bend), and it lowers
the boom (less leech tension = less mast bend). One simple
adjustment (shorten forestay and lower sail) and it has a
compound effect, but all working in the same direction.

For more radical adjustments in mast bend, I move the mast step
forward or rearward on the hull. Moving the mast step has a
small effect on side stay length, but radically effects mast rake:
1) Move mast step rearward, lengthen forestay (to get the correct
sidestay tension), and lower sail. Less mast rake = less mast bend.
2) Move mast step forward, shorten forestay, and raise sail.
More mast rake = more mast bend.

How do I determine proper side stay tension? A little wierd, but
I start with a length that pulls the plank flat (no crown) with
no weight in the boat. Plank crown: 2-1/4", deflection: 1-3/4"
with skipper weight.

For reference here are my rigging lengths:
Forestay: 144-3/4" pin to pin, assumes Sarns triangle at hound,
and a Staymaster.
Sidestay: 136" pin to pin, assumes Sarns triangle at hound and
no adjuster at plank.

Forestay hardware for mast rotation

285

Posted by: Ken Smith on December 30, 2002 at 19:30:45:

Some have mast rotation problems, especially at the leeward mark. This can be minimized with a ball bearing mast rotation cup, as sold by Peter Johns and Jeff Kent. Secondly, this is minimized by having teh mast ball located as far as possible aft in the mast socket.

The problem can be made worse if the sheet blocks are set to be driving the boom into the mast. In most conditions, the boom, with the sheet tight (two-blocked) should be neutural, neither driving the boom nor pulling it.

After all this, if the mast has slightly assemetrical bend or is bending too much, there is still a rotation problem, then do teh following:

The hound, where your shrouds attach, should be made longer. Using the Sarns triangular plate, this plate can be installed backwards, with the side shroud bent forward. Or it can be flattened to a flat plate piece. Or it can be replaced with a similar piece with the side shroud points moved further from the mast. If you do this, ensure the end fittings are connected with hardware which allows the shroud to be straight. If the shroud wants to bend at the fitting, it will fail sooner or later. Drilling the flattened Sarns fitting and using small shackle is one solution. Using an eye and shackle rather than a swaged socket is another.

Or you can kick the boom over to the right side and not change anything.

I am using a Kent spar and have not found a way to get a wider hound fitting to attach. But I am working on it. I only have mast rotation problems at the leeward mark if I let the sail luff too much as I round.

Good luck.

286

Posted by: RBR on December 31, 2002 at 05:22:34:

Dan Clapp asks a question about what hardware will solve the problem of a mast that doesn't want to rotate when coming about, a common problem when the ice is fast and there' a good breeze. One solution is found in sailing technique. The following article by Ron Sherry was first published in the December 1998 Runner Tracks - Randy Rogoski

THE RACING TACK

by Ron Sherry – US 44 – December 1998

Over the last few years, advancements in ice boat technology have radically changed the face of DN racing. For instance, the new bendy rigs have ushered in a new era of speed. However, they have also presented us with a new challenge in tacking…mast rotation problems. The following article details several techniques that have been developed by the masters of the sport in answer to this challenge, as well as some strategies for completing a smooth racing tack while maintaining speed.

The ultimate goal of a racing tack is to complete the maneuver as smoothly and safely as possible without losing speed. Before you tack, make sure there are no other boats in the area and that you have a smooth and snow free area in which to tack. To begin the tack, start turning the boat up toward the wind. Start the turn slowly with the main sheet all the way in. Keep the sail in tight and start to slide your body forward in the cockpit. When the sail tacks, lower your helmet to the cockpit floor in front of the seat back. To accomplish this, anchor your heels in the hiking rack and bend your knees to pull yourself forward. Having your helmet on the cockpit floor means you do not have to ease the sail as much to get your head under the boom and you can maintain greater speed through the turn. This trick also equalizes your weight over all three runners and gives you better steering, making for a smoother tack.

When the sail tacks, ease the sheet just enough to get your head under the boom. Continue to lay the boat off and push the boom forward and to leeward with your leeward hand. As you do this, ease the sheet and use your knees and your weather hand to steer. Usually the mast will rotate at just about the same time the boat goes up on a hike. Let the boat hike, slide your body back into position and ease the sheet slightly. The boat will then begin to come down from the hike. As it does, sheet the sail in hard. This will cause the boat to hike once more. Ease the sheet slightly and before the boat comes all the way down from the second hike, sheet it in hard again. This second hike will help you to accelerate back to top speed. Smoothly completing a tack using this technique will send you off toward the next mark with very little loss of speed.

If the mast does not rotate using these techniques, do not lay off and pump the sheet. Laying off causes you to lose distance to weather, as well as putting more pressure on the leech of the sail and less pressure on the front of the sail. This allows the front of the sail to luff and the luff curve will keep the mast from rotating. If you try tacking the boat and the mast does not rotate, Jan Gougeon recommends that you head the boat up toward the wind and allow it to slow down a little. This reduces the apparent wind pressure on the leach of the sail and will maximize distance to weather and minimize your losses. No matter which technique you use to rotate the mast, this first step is the most important.

After the boat slows down a little, lay the boat off slowly and push the boom forward and to leeward, while adjusting the sheet. There are many techniques for this maneuver, no one better than another; simply try each one and decide which works best for you. Chip Cartwright slides forward and uses his toes to rotate the mast. Mike O’Brien uses his shoulder. Some people kick the boom. I have had the most success by sliding my leeward foot back so I can press my knee against the weather side of the boom. I then use my leeward elbow against my leeward knee to leverage the boom over. The boom is connected to the sail, which is connected to the mast by the luff rope that is in the back of the mast. A mast that has not rotated has the luff grove to windward. By pushing the boom to leeward, it pulls the luff groove to leeward where it belongs.

The Europeans have developed a solid hound that is about four inches wide. The side stays are connected at the outside of this four-inch bar. When tension is placed on the weather shroud, the solid hound rotates the mast. Perhaps a Sarns’ triangle and U-strap put on backward with the bent wings toward the front would have the same effect.

Once you understand the dynamics of this issue, it is easy to come up with a solution that works for you. If you have any questions or comments, feel free to contact me at Composite Concepts. The phone number is 810 790-5557, the fax number is 810 792-3374, and the email address is c2concepts@msn.com.

Think ice.

287

Posted by: Paul Goodwin on December 31, 2002 at 12:30:00:

In Reply to: Mast rotation hardware posted by Ken Smith on December 30, 2002 at 19:30:45:

Ken hit on a key point here: "I only have mast rotation problems at
the leeward mark if I let the sail luff too much as I round".
If you are doing the leeward mark rounding properly, there should
be no opportunity for the mast to counter-rotate onto the wrong
tack. Think about it, the mast and sail stay on the same tack
going from downwind to upwind. So, for the mast to rotate onto
the wrong side, it has to be because the mainsheet tension was
low enough for the sail to flog, and the mast gets caught on the
wrong tack. In a good leeward mark rounding, the sail should
never flog.

Start the approach to the leeward mark by turning downwind and
bleeding off a little speed as you approach the mark. This also
moves you away from the mark so you can make a wider turn. Your
entry into the mark should be set up so that you are on a beam
reach well before and to leeward of the mark, and making a large
radius turn.

The reason you want a large radius turn is to minimize the G-force
from turning and help keep the boat from sliding. The sail forces
and G-forces add up during the turn, and you need to control each
one in order to come out of the turn at the highest speed.

As you start to turn towards the mark, side your hand back on
the msinsheet until it is near your shoulder, and start to ease
the sheet. The amount to ease varies with the strength of the
wind, less wind = less ease, but you should never let out too
much, since it will let the sail flog. Once the sail is eased
and you are turing, the sail will start to power up.

Pay close attention to what the boat is doing, and it will tell
you exactly what needs to be done with the mainsheet. If the
back end starts to slide (spin-out), ease the mainsheet. If the
boat stops turning, or the sail starts to luff, pull in the
sheet. Since you are turning upwind, the sheet will need to
be pulled in steadily to keep the sail from luffing.

All of this happens pretty fast, but once the techniques are
learned, it will become second nature. Besides making for a
faster rounding without rotation problems, it will take away
some of the fear of rounding in heavy wind. Proper mainsheet
handing will allow you to control your boat's heading by pulling
and easing the mainsheet. Pull in the sheet and you will head
up, and ease the sheet to bear off.

See you at the leeward mark!

Problems and solutions

Steering

475

Posted by: Doug Gaudet on January 18, 2000 at 08:13:53:

First let me start by saying the skates of topic are NOT Sarns bullnoses or high tech anything. Here in Canada those would cost me about a week of pay.
I made 1/4 inch mild steel skates with 1 inch by 3/8 inch stiffners welded in several places, sanded and painted black.
My problem is that one of the front skates has unbelievable "reverse unbalanced rudder" tendencies. When you turn the tiller - hang on, because the skate would go all the way around, just like an unbalanced rudder in reverse. And at 60 or 80 kph it will "twitch" you right out of the boat and not look back at you, with your 3 broken ribs, as you lay there, AND the boat never tipped over, it sailed away then finally layed down and waited for my son's to get me and the boat. That happened to me last year second day out.
My skates are 30 inches by 5 inches and the bolt hole is 12 inches from the back. Checking last night I found I had a very slight hollow about 4 inches long under the bolt hole. Is this my problem? The other point I want to ask about is the plans show the hole 12 inches from the back of a 30 inch skate, why is it back there and not in the middle?

479

Posted by: Ken Smith on January 19, 2000 at 01:42:22:

In Reply to: skates - "reverse rudder" torque! posted by Doug Gaudet on January 18, 2000 at 08:13:53:

My bet is that the runner is riding on an edge well forward of the pivot bolt and the steering axis, so when some side force develops, the runner wants to turn more. The steering runner should be free to kick up over ice chunks and the like, and should have a smooth profile. Sit your runner on a smooth hard surface with light behind it. It should be in contact with the surface beneath the pivot bolt and curve gracefully up about .008 (newsprint thickness) about four or five inches in front and behind the pivot. The curve should continue forward and aft. More flat or less flat is a variable depending on conditions and your ability to find a small difference in speed.

The theory with more runner in front of the pivot is to more gently launch toward orbit upon finding small obstructions. Middle seems to work okay too, at least on some of my side runners. There is too much going on up front to argue with 60 or 80 years of evolution.
Ken Smith
DN 4137

480

Posted by: Bob Dill on January 19, 2000 at 09:42:57:

In Reply to: skates - "reverse rudder" torque! posted by Doug Gaudet on January 18, 2000 at 08:13:53:

Dough,
I know of a similar problem a friend had years ago. He had the front runner pull sideways abruptly while tacking, bending his steering rod and ejecting him. He was sailing on slushy ice in fairly windy conditions. He addtibuted it to the conditions and possibly to slight reverse rake in his steering chock post. What ice conditions were you sailing in when you were ejected?
It sounds to me like your problem is the hollow in the center of the runner. How high is the hollow? (measure with a feeler gauge with the runner on a level. Did you dull a couple inches at the front and back of the sharp section of your runner? How straight is the sharp section of the runner? Does your bad runner always want to to this? How is it different from the runner that does not?
In general you put the pivot near the center (maybe slightly ahead on steering runners) of the sharp portion of the runner edge. That is the section that is sharp between the dulled areas at the ends of the runner.
It would be good to understand what causes this problem. It is not common but it certainly is dangerous when it happends. Who else out there has had this problem? Who has ideas about what might cause it?

Bob

482

Posted by: Doug Gaudet on February 09, 2000 at 08:44:48:

In Reply to: skates - "reverse rudder" torque! posted by Doug Gaudet on January 18, 2000 at 08:13:53:

FIXED, and thankful. I fixed a bunch of things while there was snow on the ice here last week.
First, in the nose of the fuselage I oversized the hole that the steering chock pipe fits in then I reset the pipe in the hole square and vertical, held it in place with small wedges, and filled the hole with epoxy and graphite. I didn't have access to oilite bushing material.
Next I took my front skate and attacked it with a 4 inch grinder and files, sandpaper and stones till my square laid on the edge of the skate let no light through from one end to the other.
I took it out sailing this past weekend and the boat and the skate worked as well as my other steering skate,(notice I didn't say perfect?) which has camber fore and aft.
Thanks to Kent and Bob for their input.

How Tight to tighten runner bolts?

827

Posted by: Andre Baby on November 20, 2003 at 15:31:38:

In Reply to: Re: Sarns chocks: which end forward? Posted by Geoff S. on November 19, 2003 at 22:17:50:

Runner bolt tightness :
I have always been perplexed by the 2 different approaches to the subject( with possibly a third ,ie the tennis ball in the chock) "really tight "versus "tight enough to barely let the nose drop.".
Really Tight favours no clink, clink, therefore less drag, maybe less alignment loss, but makes the plank twist, and allows for no following of bumps. Jeff Kent favours this method.( and does he ever go in light air, where one would think that tight would be slow !!!)
I have also seen some videos of some fast people rounding the weather mark (Swedes and US )with their windward runner looking really tight, with no dip of the nose.
Any other thoughts on the subject ?

Carrying boats around

531

Posted by: George on December 21, 2000 at 10:05:53:

In Reply to: Plans for roof rack posted by Jeff Smith on December 19, 2000 at 06:49:47:

I replaced the factory rack on my Explorer with a Yakima wing bar system. With the DN sitting between the accessory "Gunwhale Brackets", the striker doesn't hit the roof wne the striker is just in front of the forward bar. There are also other components that are made to hold a single bike wheel, but work well for the mast. Can't remember the name though. The Yakima system is stiffer than the factory rack and also a little higher. Best benefit is that it's easy to switch between accessories to accommodate the season. You can often find used stuff on eBay

What to take on the ice

Working on runners

861

Posted by: Paul Goodwin on March 02, 2004 at 09:33:47:

Several people have asked about the Black & Decker
Shopmate workbox that I was using at the Jamboree
to hold runners. This unit is no longer in production,
but can be found occasionally on Ebay. However the
Ebay prices have skyrocketed, with some final bids
higher than the original cost (must be all those
iceboaters).

I was introduced to a nice little European portable
workbench at the Worlds. This one was manufactured
by Wolfcraft, and has some pros and cons in comparison
to the Black & Decker. The Wolfcraft doesn't have
any internal storage (the Black & Decker is a rather
large box), but it is much more compact. The Wolfcraft
also has rubber feet, and works very nicely in hotel
rooms since it is less likely to scratch the surface
it's sitting on. The Wolfcraft even has a little
resevoir on the front which is the perfect size to
hold a little of the blue stuff for dipping stones
while honing.

The good news... I was tipped off that Lowes carries
the Wolfcraft bench for $30. I went to my local Lowes
and picked one up last week, and it's identical to the
one sold in Europe. A couple days ago I was at Sears,
and I saw the same workbench (rebranded under the
Sears label), also selling for $30.

I now have both types, Wolfcraft and Black & Decker.
I think the Wolfcraft will be the workbench of choice
for stoning runners in the shop, while the B&D still
has an advantage out on the ice, since it can hold
the full array of tools for touching up runners and
is the perfect height for working while sitting on
the plank.

Other Iceboats

Optimist DN

687

Posted by: Ken Smith on May 30, 2002 at 08:32:34:

Jan Adsten has ben kind enough to forward the plans accepted by DN europe. Use the links to view and print plans.

http://www.icesailing.org/junior/index.html

This site is a file repository. Open the drawings called PART 1 to PART 4, (PART 4 is runners") or if you want to see the whole european website start with:

http://www.icesailing.org/index2.shtml

and then "juniors". The plans will be opened as pdf-files if you have Acrobat Reader installed. Or I can send them to you as Word doc-files if you mail me.

You can even find them on the swedish ice sailing home page:
http://www.sisf.se/isjakt/opti/opti.htm and there you´ll find the drawings named as underlined here below:

Ice Optimist class approved rules and drawings
Sailplan and classrules (PDF)

Top view (PDF)

Fuselage and plank (PDF)

Runners

Kindest regards
Jan
----------------------------------------------------------------------------
Jan Adsten,
Östersunds Isjaktklubb
www.gather.to/isjakt
Skrakvägen 14
S-831 62 Östersund
Phone: 063 12 32 51
Internat:+46(0)63 12 32 51

Original ideas on the cheap

Saving epoxy rollers

787

Posted by: George on February 20, 2003 at 14:55:41:

In the construction of an exoxy-reinforced wood kick-up rudder for a Lightning and an oak table top, I have found a neat FOAM ROLLER TRICK for applying finishing coats.

Many times, you need multiple coats of epoxy, and want to get the second coat (or 3rd, 4th, 5th) on when the first is in the gel state (not cured) and before amine blush has developed. This gan get expensive and time consuming if you replace the roller covers after every epoxy batch.

You can keep using the same foam roller by putting it in the freezer between coats. The freezer's low temperature inhibits the epoxy from curing. It will last for at least 24 hours.

There are several benefits to this technique:
1) Don't need to replace roller covers for each coat
2) Less clean up
3) The cold roller gives you a couple more minutes to work the pot
4) Don't have to wet out a new roller cover each new pot (saves expoxy and time,a produces more consistent coats)
5) The combination of a cold, epoxy-saturated roller cover significantly reduces the likelihood of bubbles and the need for further tipping out (or later sanding!)

Original Design Ideas

802

Posted by: Rick Keevil on March 31, 2003 at 20:53:51:

I have a mast boom and sails from an albacore sailboat Is it worthwhile trying to build an iceboat around it ? Does anyone know where I can get info on such a project? Thanks Rick

803

Posted by: Ken Smith on April 01, 2003 at 08:18:33:

In Reply to: NEW TOPIC: Albacore Sail etc. posted by Rick Keevil on March 31, 2003 at 20:53:51:

Rick:

An Albacore sail and rig were designed by Ufa Fox for a planing, two man club racer, starting form an early I-14 hull, modified with a fore deck. The sail on an Albacore is much larger than the area on all but the largest contemporary iceboats. A sail boat has high drag, and the sail typically sails typically see 1.3 times the true wind speed. Sail boat sails are very full as a result. Power in a sail goes up as wind velocity squared.

Iceboats, on the other hand, are high lift, low drag vehicles. They sail 3-6 times the wind speed. Their sails are very flat and most are fully battened to make their shapes stable. A large sail like an albacore would require a very large platform for stability. Then the power developed would bend the spindly aluminum AL mast. Still the boat would not point and would be very slow off the wind.

In short, you might make a one-off boat which would be fun, but most likely you will be disappointed in the performance of the boat compared to anything else on the ice. You'd still have lots of work, need runners, etc. For similar effort you could scratch build a DN, find a used sail and rig and sail much faster and with a competitive group of others.

There are several classes of iceboats, many used equipment, and lots of development already done. I'd look elsewhere for fun on the ice.

384

Posted by: Ken Smith on December 15, 2003 at 10:37:16:

In Reply to: NEW TOPIC: hey you-Please Change posted by wayne matheson on December 08, 2003 at 17:46:37:

Wayne:

The aerodynamic advantage of a forward swept airfoil is that the tip vortex shedding is retarded and moved to the root of the foil, thus potentially reducing drag and allowing more of the foil to load. THe problem is one of stability. As the foil flexes, the tip's angle of attack tends to increase, which is an unstable situation. In the few aicraft built to push this concept, careful structural design was needed to eliminate this tendency.

In a sail on a fractionally rigged mast, bending the spar tends to pull the mast tip to leeward, open the leach and also flatten the sail. All tend to depower the sail, redcing both lift and drag. If the mast raked forward, I believe mast bend would not depower the sail. Rather the tip of a fractionally rigged mast would bend to windward, increasing the camber and the angle of attack of the top of the sail. This, too tends to be unstable.

This is not to say that it could not be made to work with a wing-mast and a careful arrangement of stays. Rather, this is to point out some of the potential problems which may have to be overcome to make it work. The Ice flyer uses a sail board rig aft of the pilot, for instance. That mast is raked forward, but the mast bend is controlled by sheet tension to a wishbone boom, rather than by sheeting to the deck. The shroud attachments are set up to not much change the sail shape/mast bend.

In the land yachts, the sail COE looks to me to be placed just aft of the center of gravity. In your proposal, moving the skipper forward moves the CG forward. Forward rake is one way to move the CE forward. Lengthening the spring board (moving the base foreard) might be a cleaner alternate solution.

Worrying about all these design issues, then making a yacht, then finding out the concept was weak, is fun for some, but I'll stick to one-design.

Ken

385

Posted by: Wolfgang on December 15, 2003 at 17:16:33:

thanks for the reply Ken that was just what I wanted to know (.what would be the effect of tilting a soft fractionally rig forward?) and I couldn't find that in the theoretical information I had at hand. I realize that forward swept foils may be very unconventional and possibly impractical to build but it is a combination of concepts which when put together provide the solution to many problems I love my D.N. dearly .I think it's design was a way ahead of it's time and all the refinement over the years has kept it as current as possible ,but there are alot of new tech concepts out there since the D.N frame work was invented. The challenge is to create a craft with the range ,versatility , speed, and econony of a D.N and to possibly improve upon it.Tough job ! But if everyone was content to continue on the same vein the D.N would never have been invented in the first place and we would stillbe sailing steern steerers .I had thought about extending the front (springboard possibly) but it didn't fit the parameters of the overall length I had set in the beginning. Building a bunch of prototypes based on "shakey " theory isn"t very attractive to me either that is why we are trying to find a way to make the design as balanced as possible on paper . I may find that moving the centre of effort far enough toward to cog is impossible with in the parameters of the design concept. if that is the case the parameters may have to change. If you can't win with the rules as they are ,change the rules
Thanks.

386

Posted by: kendnsmith@yahoo.com on December 19, 2003 at 07:16:34:

In Reply to: re: forward rake masts posted by Wolfgang on December 15, 2003 at 17:16:33:

Wolfgang:

If you want to see revolutionary and evolutionary design improvements to the breed, look at land sailing. (www.nalsa.org for an initial link) Without having to chase ice and with a year-long potential season, and with several pure development classes, evolution has moved far past ice boat evolution.

If I were to start from a fresh piece of paper with the goal of a light-weight, wide range, fast and fun alternitive design, I'd start with the 5sqm class or the sanddart class of land yacht and innovate from there. Both class uses cantilevered (unstaayed) masts, sleeved sails, a faired and reclined cockpit. The sail shape evolution is fairly well advanced. What I'd change is the axle arrangement as it is too flexible to hold runners in line.

Ken

384

Posted by: wayne matheson on December 19, 2003 at 18:57:20:

In Reply to: Re: re: forward rake masts posted by kendnsmith@yahoo.com on December 19, 2003 at 07:16:34:

ken I am an avid wind surfer. the sleeved mast that a lot of small dirtboats use was a definite consideration when considering a rig frame work. I have been looking at every high speed rig that I can find . the real problem I face is to put the weight of the pilot forward and not over losd the front runner thus making making the back runners slide out The dirt boats do seem to be into more radical designs . The more I look at all the yatchs I can see that the way that they achieve lateral balance is by extending the front until the cog and coe are closely alinged . one of my objectives is car- top ability (12` approx. ) A long detachable springboard may be my only solution but it would be more trouble to assemble (steering etc.)heavier Another thought was to move the plank forward . The orignal concept was to have the plank at the very back of the boat. AS you move the plank foward more weight is put on the plank . this moves the cog back without movig the coe. the bad thing about this is the shortened runner base and I am assuming the centre of lateral resistance will also be moved forward farther away from the sails coe, Will the extra weight on the plank give me apositive net effect.or will the shift of the clr forward cancel out any gain achieved by weighing the plank? Maybe a combination of moving the plank forward and a shorter spring board. It appears to me that the coe of a D.N is somewhere near the plank laterally speaking ,The plank is heavily weighed by the pilot position .It is the weight on the plank that allows the coe of the sail to be so far aft. It is proving a real challenge to fit all the required elements into a pakage you can strap onto a roof rack. one good thing about a rear sail is that the cog should move back as the rig loads up. so far the only way I can make all the forces line up in static balance in a 12' frame work is to over lap the sailor and rig Which is very complicated to realize(mast over your chest). One other question ,Is the static cog equal the same as its clr and if not how can it (clr) be determined from a give cog Thanks
wayne aka wolfgang

Skeeters

398

Posted by: Jordan Glaser on February 10, 2004 at 08:00:39:

In Reply to: Re: DN bottoming out affect pointing? posted by Paul Goodwin on February 09, 2004 at 23:22:26:

Thanks for the response Paul, I'm sure it will be of great help until I get the plank stiffened (?S glass). Some of the suggestions sound like a lighter air set up (tighter stays, less rake, boom pulleys forward with mast de-rotation). Once the plank is stiffened or I lose 35 pounds (ha ha), how much would I revert the set-up for high gusty winds? I know that each DN has its own personality.

399

Posted by: Paul Goodwin on February 11, 2004 at 08:39:24:

In Reply to: Re: DN bottoming out affect pointing? posted by Jordan Glaser on February 10, 2004 at 08:00:39:

Actually, I think you've got the rig tuning steps backward, at
least by my way of thinking.

In strong wind, the mast bend will tend to get out of control,
so you should move the mast step back and decrease mast rake.
Also pull back agressively on the boom to derotate the mast.

If it's really windy and the mast is bending too much (even
after moving the mast step back and decreasing rake), then
lower the halyard so you can't pull the mainsheet in so far.

401

Posted by: Jordan Glaser on February 11, 2004 at 20:50:34:

In Reply to: Re: DN bottoming out affect pointing? posted by dave on February 11, 2004 at 16:13:10:

Your right Paul, I had it backwards. I spent too much time reading Think Ice and had little experience with very bendy masts......Here's another question....My bubble E Skeeter has a carbon mast that is somewhat heavy & bendy. The boat is ~100 pounds lighter (500 total) than Insanity and seems to love to hike excessively when compared with its peers when sailing in those heavy WI winds.....Besides for putting up the blade, what's the best approach? Add ballast (in middle or rear of boat?)? Lengthen sidestays? Adjust rake? Adjust mast step? Adjust pulleys on Boom? The Skeeter is wickedly fast, but I'm sure many of the DN set-up moves are very applicable and will make the skeeter move even quicker...Thanks!

402

Posted by: Paul Goodwin on February 12, 2004 at 08:09:46:

In Reply to: Re: DN bottoming out affect pointing? posted by Jordan Glaser on February 11, 2004 at 20:50:34:

Hi Jordon,

Asking a DN'er questions on how to set up a Skeeter - I'm putting
this one on the calender!!!!!

Seriously, I'm not very familiar with Skeeter setup, although
my bubble C-Skeeter should be on the ice next season so I
better start learning.

Adjusting rake or the mast step position should affect weather
helm more than tendency to hike. Side rake will help, although
I remember sailing Magic, and we tightened the side stays
until the boat started to broach upwind, then slack them off
a bit and the boat would settle back down. This leads to
another question, what's your plank width compared to your
peers?

I was amazed to talk to Dan Clapp and find out he puts 100lb
of ballast over the plank. Seems like a waste to add weight,
but I understand how it can help. The front seater has too
much weight on the front of the boat so moving the CG back
makes "some" sense. The boat I'm building will weigh more
like 350lb, and I'm hoping to capitalize on the low weight
and low aspect sail plan at the starting line and coming out
of tacks (I'm sure I'll get killed at top speed).

Sorry I'm not more help, I should be asking you these questions!

406

Posted by: Jordan Glaser on February 12, 2004 at 21:13:46:

In Reply to: Re: DN bottoming out affect pointing? posted by Paul Goodwin on February 12, 2004 at 08:09:46:

Thanks for your comments Paul. I'm glad I made your day! I think that it's great that you're building a front-cab C Skeeter. Send some pictures when you can.

The plank on Attitude & Insanity are both 22 feet. Masts are 26'. Some of the Skeeters are 2' higher & 3' wider. My mast was the first one Dan made, so it wasn't vacuum-bagged and therefore heavier, but it is the most flexible of all the E Skeeter masts that he built. The pink boat is just lighter & loves to hike. I started to use ballast last season & it does control hikes. In heavy winds, with ballast or not, the boat just wants to shoot off the line. I'm glad I ran alot of full court and rode my bike up many mountains or else I wouldn't be able to hold her back. In moderate & even light winds she still hikes plenty, but she's more of a push off the line, so I'd rather keep her light (& learn any lessons I can from you DN guys)
Downwind on heavy air days, the g-forces glue your helmet to the back of the cockpit & it's all a blur when you look laterally through the canopy. I'm thankful to Dan Clapp for creating this work of "art on runners."

Two person boats

484

Posted by: Randy Beaton on February 16, 2000 at 12:43:32:

In Reply to: Looking for two person boat design posted by Bill Adams on February 16, 2000 at 09:33:13:

Bill,

Your request sounds like a Nite. I am not sure on the sail area but a Nite mast runs around 18'. I suspect these boats may use DN type fittings. There is a class association for these boats that shouldn't be too hard too track down.

Another design for which plans are available is a Yankee. It's a B Skeeter with a 23' mast running 75sq. ft. The hull is 19'. There is a class association for these boats too.

Another approach I've seen is a bastardized DN design. Basically a Dn made bigger. From what I gather it seems every club seems to have 1 or 2 of these homebuilds around. One is pictured in the 'Think Ice' book.

485

Posted by: Jeff Soderholm on February 16, 2000 at 22:14:07:

In Reply to: Looking for two person boat design posted by Bill Adams on February 16, 2000 at 09:33:13:

Lloyd Roberts Gambit is an excellent two seat iceboat design that uses DN hardware. There are several active sailors that can usually be found sailing these boats in the New England area. I have had numerous opportunity to sail them and can recommend them based on personal experience. His e-mail address is robertsl@midcoast.com

491

Posted by: mike derusha on March 21, 2000 at 18:39:44:

In Reply to: Looking for two person boat design posted by Bill Adams on February 16, 2000 at 09:33:13:

hello bill our club the menekaune ice boat club has developed our own two seater our fuselage is basically a wide dn 13 ft long 36 wide slightly tapererd stearn (mostly square). the boat has a four foot spring board 12 foot plank and renegade rig we've built seven of these craft and it's a very popular boat since 1989.

Colorful entertainment and writing

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Posted by: Will on White Bear Lake on March 06, 2002 at 00:20:13:

In Reply to: Re: helmets posted by Roger Duffy on March 03, 2002 at 12:02:24:

I was trying to catch those pesky DN SPEED DEMONS on Lake Minnetonka Saturday (they MUST cheat somehow...) when I blew out one of the wooden bodies of my beautiful 1/4" insert runners. Busted it right off at the bolt hole leaving me high and dry in the middle of the lake and further from home than I have ever been (or so it felt).

It may be God's will (survival of the fittest by natural selection?) because I was in the awful position of bringing up the rear of the pack due to my START-FROM-HELL in which I fell down, Whoops, landing belly-first directly onto the plank as the boat lurched and hiked off the line. After being dragged 100 yards or so looking like a deer on the fender of a hunter's car, I then tried to stand up, but fell forward, landing face-first, belly-down into the bouncing cockpit. Since all of this happened while pulling hard on the mainsheet I was able to exceed my daily dose of adrenalin as the tight sail was driving the boat about 50 mph, fully at the mercy of the ruthless wind. Frantically yelling, "WHO-O-A-H NELLY!" (and other things), I managed to eventually slow her down. I only fell back onto the plank twice more before I got back into the cockpit the right way. You gotta be good to be this bad, right? Then it was: "Hey, where did everybody go?"

But , I digress. There is no repairing my ruined pride, so my main concern now is how to repair the lost runner. I bought these inserts used and have never made any myself. Should I just replace the broken one, or both? Are there body "blanks" available? Best material is? Do I need a jig to hold the runner straight while I assemble a new body?

All help appreciated. I must redeem myself to the ICE GODS of LAKE MINNETONKA!

All Hail,

WWBL

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Posted by: Will on White Bear Lake on January 19, 2004 at 17:38:40:

Based on observation anyway. In our area (and I am talking about Recreational sailing NOT RACING) it seems that there are far more Nites that crash than DNs and yet we seem to have roughly equal numbers of both types of boats on the ice. It also seems, in general, the Nite pilots get far more serious injuries. Assuming this to be true...why?

I believe it has to do with the PERCEPTION of safety vs. the REALITY. This was brought home to me by an article entitled "Big and Bad" in the January 12, 2004 New Yorker. The artilce clearly illustrates why an SUV is much more likely to kill or cripple the driver and occupants (as well as those they clobber) than a good minivan or small agile car. In addition to being basically a crappy rigid pick-up frame covered with soft round corners, more seats, and cup holders, and the unarguable fact that the SUVs roll more and handle and brake poorly, they propose that MAIN REASON that SUV drivers and passengers are statistically 4X as likely to die at the wheel (238 fatalities/million vehicles on the road vs. 60 with a Toyota Avalon) or 67 for a Chrysler minivan) is that SUV'S FEEL SAFER THAN THEY ARE (all that chrome and rubber in front of you, 4WD, sound insulation, high seating position), while small cars FEEL MORE DANGEROUS THAN THEY ARE (engineered crumple-zones, MacPherson struts, real discs, low seating height, true road feel). This perception affects driving skills greatly, with the former lulling you into complacency, the latter more likely to cause you to pay attention.

When I read this I realized that piloting a DN generally tends to be a hair-raising experience requiring supurb attention to detail, particularly in super high wind or bad ice. The perceived speed is much greater than the actual speed virtually all the time. You watch for bumps, cracks and drifts! All this makes for an attentive and careful sailor! Death (from multiple sources) FEELS imminent most of the time!

Nites, on the other hand (while being intrinsically as safe, if not safer boats) are by comparison too comfortable, too warm and basically too secure feeling. As a result, the pilot has far less "road feel" and tends to increase the speed and course accordingly, just add some tinted windows and cup-holders for the full effect. One time I really did see a Nite guy on the cell phone (I'm serious!) as he went by. Yipes!

I plan to spend lots of time in both of these wonderful craft this winter (and many more winters to come, God willing) but I just hope I can always find and hold that edge without going over it. Let's all stay awake out there, whatever we ride!

WWBL

P.S. That SUV that busted up one of our WBL DNs Saturday was clipping right along when they hit. I would imagine some of the above SUV material applies to why they may not have seen the boat coming, and why they couldn't avoid the collision. We don't know what the DN guy was thinking about but it was more likely to be dodging drifts, not speeding hulks of steel.