: I was thinking along similar lines but for space and stability reasons. What
: I had in mind would be to use plywood to make the bottom of a Putz Walrus
: and hopefully come up with something rigid enough to skip the floor beams.
: Build the rest of the frame normally and skin the whole thing. This would
: leave more room for big feet and lower the seat an inch or two. Not that
: this would help any when you ram a rock but maybe you can epoxy the skin
: (poly?) right on to the plywood.

People have been using canvas to cover the decks of sailboats for a long time. It is held on to the wooden decks basically by a coat of paint. Paint the deck, lay on the canvas while the paint is wet, then cover with a couple more coats of paint. Yes, you can eventually peel the canvas off, but for the most part it will stay put. If you use this idea for adhering your canvas or polyester fabric to the wooden bottom of your kayak, then it seems to me that even a long gash that penetrated the fabric would not cause immediate failure. It could take a long time (days, weeks, months) for the torn fabric to wear enough that it started to peel off -- a process that could be stopped at anytime with some judiciously applied duct tape -- and in the meantime, the paint surrounding the cut fabric should still keep out the water.

If you go with plywood floorboards for a Putz Walrus, let me also suggest you scrap the thin wood trestling and replace all those little sticks with small panels of plywood. Use 2 foot long plywood panels (maybe 7 to 8 inches wide) that are spaced a foot apart. Hold these to the chines with epoxy and some small brass screws. You can make them wider than you need (oversize) and later trim them flush with the chine using a router with a panel cutting bit and a roller guide. Large holes drilled in these panels will cut some weight.

Look at the method used for bracing the frames in Klepper kayaks and you'll see the idea. (www.klepper.com)

Hope this helps

PGJ