When using a urethane coating over 9 ounce polyester, the urethane penetrated in places, I can see where it has caused the skin to adhere to the frame. In time these will break loose. I have read in the baidarka mailing list archives about this, and some of the time it does happen.

My test with epoxy showed some penetration and sticking too. Snow-Roof on #10 canvas does not penetrate.

When the canvas/Snow-Roof walrus is on my rack, I can pull the stern down a good 6". I don't hear any cracking or tearing when I do this. The canvas is a little loose and has a lot of stretch and Elast-o-Seal stretches 1000%, while Snow-Roof only stretches 400%. The wood in that kayak is mainly western red cedar which has a lot of flex.

Technically the loose skin may be stronger, but the Walrus type construction appears to be quite durable.

Mike

: Question: In the finished yak(not during bldg), what are the relative
: benefits or not of an attached skin(like the walrus w/ staples or copper
: nails) or of a sewed skin like the traditionals.

: Or when you hyponalize or urethane the traditional, does the coating soak
: thru anyway to adhere the skin to the frame.

: And in Jay Babina's yak, does the epoxy soak thru the glass and adhere the
: skin to the frame.

: What contribution to the overal strength of a skin yak is the skin - adhered
: and not. Like in a stressful situation, what breaks first.(not talking
: about rocks)

: Or which is stronger: a walrus(attached) or a traditional(not so attached)?

: any thoughts?

: -mick