I am working on my 3rd kayak that I have built out of the cheap stuff. The first two were built out of 1/8" mahogany from "plans" I found in a wooden boat magazine about 10 years ago. These kayaks had compound bends (I think that was what it was called - bent in 2 directions) and the cheap wood worked fine.

The current boat I am working on is an ocean kayak and I used 1/4" rotary mahogany instead of 4mm okume for the hull. It has worked fine and I think the extra thickness has added a little strength to the hull. I broke down and bought a sheet of 4mm okume marine plywood for the deck since it has to bend a bit more. The okume seems much less rigid than the cheap stuff - probably since it isn't as thick.

I think for most applications the cheap stuff will work fine, you just have to make sure to pick out the best sheets they have and make a judgment call baed on how it will be used. If it doesn't have to bend a lot and you are going to glass over it anyway I would go with the cheaper stuff. (my $0.02)

Jimmy

: I've never used marine-grade plywood, and my only experience with lauan is in
: the boat I'm constructing now. I don't know how they compare in strength
: and rigidity, but I've had to glass both sides of all my lauan - it just
: seemed too flexible without it. I'm sure that this flexibility was more
: noticible on the design I'm building (SK S&G) with it's flat deck
: sections. I'm not sure that marine-grade plywood would have behaved much
: differently in those areas, but the plans only call for taping interior
: seams.

: With all the extra glass, and the thicker (5mm) lauan, my boat is not going
: to be a lightweight. Once outfitted, I'll be happy if it comes in under
: 50lbs.

: Also, the lauan I'm using is butt-ugly, but that's okay because I've always
: intended to paint it. If you want to finish bright, lauan might not be the
: best choice. My $0.02

: Ross