I have some encouraging news about the Revolutionply I'm using for the bottom of this pirogue. I cut a 3" x 4" piece and threw it in a bucket of water 2 weeks ago. I've been checking it every couple of days for any changes. After two weeks.......nothing. No swelling, cupping, warping, splitting or delamination. Well, maybe about a 1/6" of a slight twist. Looks just like it did 10 minutes after it hit the water. They don't market it as "marine plywood" but, in my book, it passes that test. I have my doubts as to whether any real marine plywood would do as well.
Joey