If you going to fiberglass and cloth it you make it out of Luan. If you don't want to fiberglass the whole thing A 1/4 sheet of Marine plywood is $52, you can get 16' sheets at Robichaux in Raceland for $140 or so. I would still tape and fiberglass the seams. If you have a decent table saw the end pieces don't look to be to hard to cut.
LSU Ag center has a tutorial on it on their website. There is also a good tutorial on thehulltruth.
http://www.lsuagcenter.com/en/our_of...nt/Pirogue.htm
http://www.thehulltruth.com/boating-...n-pirogue.html