Subject: Re: [baidarka] Greenland gunwale angle
From: brian.nystrom@att.net
Date: Fri Oct 12 2001 - 16:31:38 EDT
> I am planning to build a Greenland kayak this winter, and am trying to decide
> whether to use Bob Boucher's video or Chris Cunningham's article for basic
> instructions.
I have both of these, plus Robert Morris' book (and Zimmerly's and Dyson's and...). I used the book primarily. Cunninham's article provides alternative approaches and has more detail on subjects such as rib placement, where the book is a bit weak. I'm glad I purchased the video so I could see the process in action, but I didn't use much of the information therein. Boucher's method obviously works, but much of it is crude to the point that I cannot bring myself to use it. It's probably just because I've spent too many years in Q/A and Q/C positions. I also can't see the point in using rot-prone natural fibers (jute, etc.) for lashing, when synthetic equivalents that are impervious to water are readily available.
To his credit, I suspect his method is more "traditional", since it uses all natural materials and mostly hand tools.
> Bob Boucher's video sets the angle of the gunwales at 28 degrees, Chris
> Cunningham's article and Rob Morris's book use 17 degrees. What are the
> advantages and disadvantages of the two?
With 17 degree gunwales, you get a reasonable amount of curvature at the sheer and the skin is supposed to seal tightly against the gunwale boards. In reality, I fould that the skin separates from the gunwales ~4' from each end. I built my boat with a low height to sheer (6.5" at the backrest), which should have kept the skin close to the gunwales. On a boat with more depth, the seaparation will occur sooner.
The 17 degree gunwales are also supposed to result in more of a muliti-chined hull (at least in the center of the boat), which it does. The 28 degree gunwales should produce a classic, four panel, hard-chine hull. It's a matter of personal preference.
> Are both traditionally used in Greenland?
> Does the gunwale using Bob Boucher's method sit parallel to the skin
> or does it form a gap along the lower inside edge?
It gaps along the bottom edge for the full length. I guess the philosophy is that if you cannot seal the water, sand, etc. out of the area between the gunwales and skin, you may as well provide for good drainage and air flow. It will still seal where the skin wraps over the top of the gunwale. This makes sense, but you notice that he ended up with so much sheer curvature that he had to weight the frame to take some of it out. This has the effect of putting the keel in tension, which may make for a stronger boat, but I'm not sure it really makes any difference.
IIRC, Morris does comment on this intentional gap philosophy in his book, but not in any detail.
Either way you go, you'll get a usable boat. I was already planning my second one before I was halfway through the first, and the others I know who've built SOF boats have done the same. It's not like building a wood boat where you're duplicating the designer's creation; every skin boat has a unique shape. You probably won't build just one, so just pick a method or combination of methods that makes sense to you and go with it. When you encounter specific questions along the way (and you will), post them here.
Have fun building!
Brian
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