Hull length, sideboards, bottom, cockpit

[jori]

Started building my new DN hull this month. Thanks, everyone, for the DN Collective Wisdom site; it's great! After reading everyone's input, think I'll go for a flat vs. curved bottom, just under maximum length hull, maximum cockpit length, and minimum height sideboards, unless someone can and wants to convince me otherwise. Wood is sitka. My height is 5'10", weight 145.

The only thing I missed somehow is what the minimum height of the sideboards should be. How many inches? I can go back and peruse, unless someone has some input on this.

Thanks,
Jori

[DN 805]

Hi Jory

The best way to start to lay out a hull is to open the year book to the specifications.  Therein you will find the allowed dimensions and the tolerances.
Be sure to read the section on interpretations of the specifications.    This is the only way you will know for sure that the end product of your efforts is a DN.

If you have any difficulty understanding the specs, tolerances, interpretations, feel free to contact me or Paul Goodwin. 

You've got six months until we hit this ice.  See ya then.

....Jane Pegel

[Geoff Sobering]

I don't mean to hijack Jori's thread, but I think my question is closely related to hers.

What is the current thinking/opinions about sideboard height (max or min) and hull length (also max vs. min)?

Personally, when I built my boat in 2005 I went max-length and nearly max-height, with more height at the tail.
I choose max-length for the extra effective-purchase on the mainsheet. 
The max-height came from 1) wanting a bit more security in the cockpit, and 2) trying to eliminate the need for back-deck riser-block.

After looking at some "Goodwin Plans" boats, I'm not sure about the importance of sideboard height, but I still like the idea of a max-length hull.  I'm curious what other folks think about those two dimensions (and why you made your choice).

Cheers,

Geoff S.
US-5156

[DN 805]

If you walk through the fleet at a championship, you can find long boats, short boats, low boats, and  tall boats.     In the construction of the DN it seems that a critical area is where the loads of the rig transfer from the forward area where the structure is framed in an enclosure that includes the deck and bottom to the area of the open cockpit where the skipper's body thrashes around.   Be sure the cockpit area is supported adequately and there is reinforcement where the cockpit meets the decked areas to accommodate the transfer of the loads.  This is particularly critical when the cockpit is extended forward to the maximum allowed dimension and the bendy rigs load up the area of the mast step. 

With respect to what is the fastest design?  I am convinced that the  most important component lies between the ears of the skipper in the cockpit. 

...Jane Pegel

[Geoff Sobering]

I am convinced that the  most important component lies between the ears of the skipper in the cockpit.

Agreed!  But it seems these days, those ears spend more time in the shop than in the cockpit! 

I'm only asking because one has to make a decision on these parameters when you build a boat, and it seems better to get some opinions and use them in the decision, rather than just flip a coin. 

Cheers,

Geoff S.

[Bob Gray]

  I completely agree with Jane, you go from a very strong enclosed structure under the mast step to basically an open topped box at the cockpit. This is a very high stress spot in the boat and to try to mke this area a little stronger, I run the external grab rails to just about the forward limit to beef up this area.

[jori]

Very interesting! Thanks, Jane, Geoff and Bob. I want more cockpit room than I had in my old hull, but not too much "thrashing around" -- although the Scrambler used to be my favorite ride at the Slinger County Fair. (Hmm...) Anyway, my 60-year-old DN, which I am now passing onto my son for a while, was very strong and reinforced where you describe with these big, solid chunks of wood and glue. Geoff, Byron and I sure carved out a lot of wood when we extended the cockpit forward to just behind the mast a couple of years ago. (I think it was originally built for a child.) It seemed like too much old, thick, unnecessary wood at the time, and I have been excited about building a much lighter craft--one that I can actually lift--but when I read your reminders about the stress of all that rigging on a shallow open box, well, this is good basic advice and I appreciate it. (Geoff and Jim Norhaus are also building Jim's new DN at the same time, so it's great seeing one come together that's just a few steps ahead of mine.)
Jori

[DN 805]

Hi Jori
Weight is not necessary to have strength.  I sail a long, tall hull that is one pound over minimum weight and because I'm short, the cockpit is short.  The easiest way to save weight is to wipe up any excess epoxy.  Think about it, how heavy are those little cups of epoxy and filler?   Mate surfaces carefully so you don't need to slop on excess  epoxy.  A given volume of sitka weighs less than the equal volume of epoxy and filler. 

Keep in mind that once we get to June 21st the days will be getting shorter and we're on our way to making ice.

See ya!

...Jane

[us5285]

    Great points all. I went through this same thought process last summer. I decided to and built one of Pauls boats (with one slight modification) using his excellent plans. I am also using Rons mast,plank and stay demensions.  The most dominate factor in making this decision was that at any major regetta, I can walk over to one of many great DN sailors in the country, look at their rig and put mine in the same spot.  Although you might have to tune slightly for your weight and sailing style, these set-ups have been pretty close right out of the box. 
     I found I am not varying much from these basic settings, and I used to be one that made huge changes after every race.  I now spend more time trying to sail as smooth as possible.
     Have fun building!!!  Tinkering with the boat is one of the best parts of this great sport.

Chris US5285

     P.S.  As for weight, if you can pre-weigh your sideboard wood, do so.  I found some pretty large weight differences, from board to board, POUNDS of weight differences!
     

[Bob Gray]

Be careful setting up like someone else. I once pulled my boat up next to the world champ and tried to set my boat up just like his. I am sad to report I went from fairly slow to really slow. There are a lot of things that control where the sweet spot is for an individual boat. One of the biggest is the mast to headstay angle which is a major factor controlling mast bend (as is sidestay slop and plank stiffness among other things). The nose of a boat may be from 3-6" in front of the steering runner and the standard Sarns mast step adjust plate allows for 5 1/4" of adjustment and there is a 6" window it sits in. Is the plate at the forward limit or the aft limit. One inch or more differences in this dimension can make a significant difference in mast bend. There is one trick that can help here and that is to take a tape ruler and measure the perpendicular distance from the headstay and the center of the mast step ball. That dimension will get you in the ball park.

[us5285]

I agree, that whole apples and oranges thing screwed me up for the last 5 years. That's why I was careful to follow Paul's plans closely and use Ron's mast, plank, and stay lengths. There is no doubt that you have to pick carefully which boats you choose to similarily adjust to.  It very well might just be a fluke or something and no doubt I'm not consistant. But in my own expierence I sure feel faster and I'm not driving myself crazy re-inventing the wheel.
 Sure is cool to be thinking about iceboating in mid-June.

Chris US5285

[RANDY ROGOSKI]

Summer is the best time to work on the DN program.

This week I prepped my runners for the upcoming season.

When it gets cold, I want to have my program ready to roll, and look for ice.

Randy Rogoski
DN US 4192

[Jordana]

Hi everyone, it's Jori, and I'm back to working on my DN hull after borrowing Geoff's for the season and adding a new boom, stays and other hardware.

I'm having trouble locating two 4' x 8' sheets of 3mm Okoume plywood in the Madison area. (I'm trying to avoid paying shipping.) McCormick only has 4 mm Okoume, Workbench has 3 mm Baltic Birch but only 5' x 5' -- they do have 3 mm  Luan Philippine mahagony 4' x 8',   BVC Hardwood--I can't even find a phone number for them that works. (608-244-8780 not in service)

Suggestions, anyone?
Thanks,
Jori
DN 5397

(Also, since some of you have asked, for what it's worth, I am a dues-paying IDNIYA member although my name was left out of the directory. Hope to finally make an assoc. regatta next season!)

[Scott Brown]

Jori:

This may get you to an answer.  Maybe not.  Buffalo (MN) Veneer and Plywood sells plywood used for doors.  It's 1/8" and comes in many wood varieties.

501 6th Ave NE
Buffalo, MN , 55313-1655 
Phone: 763-682-1822
FAX: 763-682-0795

We bought wood used to make door skins and it works great.  At 1/8th, just be sure you don't select wood that's just veneer sandwiched around "glued dust."  Granted, it's a long drive from Madison, but these guys may know who supplies door skins in the Madison area.

Just a try.

Scott
5298

[Jordana]

Thank you, Scott! I think I'm going to go with 3mm 5' x 5' baltic birch from the Workbench right here in Madison. That was originally Plan B, but after mulling it over for a few weeks, I'm thinking a cheaper unit cost and no shipping charge is the way to go.

Jori