You're correct, this plywood would fall to pieces if exposed to water. It was considerably cheaper and a 1/4" thicker. I'll probably make up the cost in sealing it properly.

: My understanding of most birch cabinet plywood is that it isn't built with
: waterproof glue (though I could easily be misinformed). Since you'll
: presumably be using the boat in somewhat damp conditions, this could prove
: to be a bit of a problem. You're right that end grain soaks up a lot of
: fluid - whether epoxy or water. Personally - no matter what I coated it
: with - I'd rather use really ugly exterior grade plywood than really
: pretty interior grade. It'll be hidden inside the boat, in any case.

: But, maybe your birch plywood has waterproof glue? I do hope so, since
: cutting out those frames gets to be a chore . . . .

: Good luck!
: Dave