DN NA Class

Hello
I have asked around and it seems like the Kenyon D section was the most popular DN mast in the aluminum age.
According to the builder the D mast is gone...don't know why but it sounds like the dies no longer exist.
There is a newer Kenyon mast that would measure in, unfortunately they have no stock of the tube.  After speaking with the builder they said that they would agree to make a run of the tube if we could get an order for >100'...so at least 7 rigs.

I think I would like one of these masts for my buffalo boat, thats the one I let others take out and a "bulletproof" aluminum rig for a lot less than a carbon/glass mast seems like it would be a good idea.

I am trying to gauge interest so please reply if you are interested in getting in on this order.

Think Ice
Aaron

I have 1 or 2 Kenyon blanks available, DN length. Also, There is one in my group available complete. Located in Western NY, 14712 area.

The Kenyon 2040 section (and rigging hardware) is still listed on their web-site:

http://www.rigrite.com/spars/kenyon_spars/2040-mast.html

Jeff,
That sounds great, I have a friend whose family lives up in Bemus Point and he will be visiting there soon. He can grab the masts when he goes home next.
Please call or email me and we can work out the specifics.
Thanks,
Aaron
732-865-6736
dn5450@gmail.com

To the other Geoff,
Yeah thats who i contacted, they don't have any stock of the tube over there, the woman who answered was the one who said she needed 100' of tube ordered to make a run.
She said that she gets calls all of the time but doesn't want to be involved with such small orders, which is why I was trying to get an order together.
I don't know if you've ever worked with Rigrite before, but they are notoriously very slow which is why i wanted to start an order now.

Thanks for the info though cant wait for the season...i'm about through with going 8 knots.
Cheers,
Aaron

Any idea on pricing?

Aaron: I'd meant to add in my earlier post that I thought it would probably be better/cheaper to find someone's old aluminum mast, rather than going to all the trouble of trying to get new ones made.

Around here a bare extrusion seems to go for about $200 and a complete mast about $300. Some of the first-generation composite masts (ex. a Sherry Whip) are beginning to come down near that range.

I'm also interested in the price for a 16' length of extrusion, mostly just to see how it compares with the used prices.

Cheers,

Geoff S.

If Aaron, decides to pass, I'll post prices.

I have 1 blank and 1 complete.

I have an aluminum mast that I haven't used in years. I'll have it with me at Williams Bay on the 31st.

Ted Bowen
920-231-2705
tbowen24@gmail.com

This thread reminds me of a conversation I recently had with a land sailer on the west coast. It's a bit off topic, but this may be useful for the casual sailor....

These guys are taking light weight aluminum masts which can be bent through over sheeting as these old Kenyon masts can and strengthening them by applying a layer of woven carbon or glass over the surface.

You can purchase woven tubes similar to a sock, it expands and contracts easily in diameter and can conform to the substrate. The mast simply needs to be sanded rough and clean, then the sock is applied over the length and soaked with resin and bound with shrink wrap tape to cure. He suggested 1 layer end to end, another layer over the center 75%, and a third layer over the center 67%.

While the mast will be stiffer than a strictly glass/carbon mast and there for harder to sheet, it will not bend and not recover.

Yikes!
I think that three layers of carbon (unless it's super light-weight) would make a Kenyon 2040 mast almost unbendable.
I can't help but think that unless the material is super-inexpensive the combination of an aluminum mast and all the glass/carbon and epoxy would bump the price up into the range of a good used composite mast.

Another method from the heyday of aluminum masts (that is less expensive and doesn't stiffen the mast) is to insert an "anti-oilcan" stick or stack of disks into the mast section so that the walls can't collapse under high load. This was particularly important with the thin-walled "Norton Wing" sections that would bend nicely (as they say, "it's fastest just before it breaks...". I seem to remember the Kenyon was considered pretty "bullet proof" (at least compared with the Norton).

Cheers,

Geoff S.

  I put one of those wood sticks in my bent Kenyon mast.  I bent it back and then put in a simple 1X2 up inside the mast.  Jane Pegel gave the me the tapering dimensions for the stick.   Noisy, but it worked great, won the silver fleet in 1990 with it.  The mast would bend so far, then the stick engaged and stiffened the section, then the boat hiked up; pretty simple.

Ditto for my Norton wing!

One item: the point of the stick wasn't to stiffen the mast, but rather to keep the walls from collapsing inward (the failure mode of most masts that are bent too much).

Kyle Metzlof built a "spine" of plywood disks that same shape as the inside of the mast-section, held together with a piece of line. They had very little effect on the section's intrinsic flexibility, but were almost 100% effective at preventing oil-canning. I think he may still have the mast somewhere. IIRC, it was a thin-wall extrusion of some fairly exotic alloy that bent almost as well as a composite mast. I think he was sailing it when he finished in the middle of the Silver fleet in the 2002 Western Regional Regatta (against fleet of almost all composite masts).

The number of plys may not work out with the kenyon, maybe 1 is good?

At the time, I was tinking of converting my kenyon blanks to a C-Skeeter mast. I was going to weld a couple of 16' kenyons together to make the 20'3" length and then reinforce with the f/g sock.

I do have 1 Kenyon blank left for $150

Personally, I'd use fiberglass. It's a much better spring than carbon (although it is heavier). If you do use carbon, I'd keep the angle relative to the mast no more than 45 degrees (0 around the mast, 90 along the length of the mast).

For example, Jeff Kent builds his composite masts with about 1/2 the wall thickness in carbon, but it's all on the inside, and (IIRC) 80% is at 0 degrees for hoop-strength (to keep the mast from oil-canning) and the other 20% is +/- 45 degrees for torsional stiffness. Almost all the bending loads are carried by the fiberglass outer laminations.


It would be a pretty lousy wing-mast (IMHO) because the fore-aft dimension is so short. If you look at all the larger boats, Renegades, C-skeeters, and others (including stern-steerers) you'll see the thickness of the spar as a fraction of the fore-aft dimension is much smaller than the 2:1 in a DN mast. Tom Speer has an excellent article on wing-mast aerodynamics: http://www.tspeer.com/Wingmasts/teardropPaper.htm

If you do go that route, most masts composed of multiple sections use an internal sleeve. That way the exterior dimensions of the mast are constant over the whole length.

Cheers,

Geoff S.

I'd say that any one interested in this blank wants a recreational mast and would not need any reinforcement.

I have had a few over the years and they were fine. I do have a glass DN mast for now. My next project is to build a Skeeter wing mast using a prepreg glass process. I had just brought up the over coating info out of interest in what others have done.

Cool!

I hope you'll post some reports about how it goes. I'm particularly interested in how one works with prepreg in a "homebuilder" environment.

Cheers,

Geoff S.

I have sold all the Kenyon Extrusions. The last one went at the NEIYA swap meet yesterday.

On the prepreg, We are forming a foam core with an aluminum sail tube. The prepregs will be wrapped over the foam and both over and under the tube.

I am undecided between shrink tape vs. vacuum bag. We do a lot with various shrink tapes where I work. Although there are a fair variety of shrink force and % available, I am unsure if I can get a uniform enough pretension by hand. Also, With the long crossection of a wing shape, I'm concerned over the compaction force available at the middle of the sides where the bending stresses will be greatest.

We are building a curing box using construction isoboard. The heaters will be electric baseboard strips and i will rig a controller with thermocouples. The heating profile is important, you need to provide enough time for the resins to flow and the air to bled out before reaching cure temperature.

The first mast or 2 will be throw aways. I'm using prepregs and scrim that are available to me as product that is nearing end of shelf life. I have 5%zero/95%90 and 50/50. both are about 12 oz fabrics.