: Is exterior grade ply good enough for a S+G or do I need to buy marine grade?
: I cant find any marine suppliers around here likely....kirk

Well, if you are building a disposable or experimental, and temporary boat, some carefully chosen exterior grade ply might possibly be acceptable. Many boats have been built from AC plywood, despite its many shortcomings.

But . . . it's a false economy if you hope to create a worthwhile boat. You would be much better served to spend the extra $50-100 and use marine ply. It should have zero voids, more plys, be much lighter and should last much longer. Not to mention that it is difficult to find exterior grade ply under 1/4" (6mm) thick, and kayaks are generally made from 4mm thick wood.

You might consider, too, that, on the water, your life, or that of others, kind of depends on the quality of your hull!

You can order good plywood from several websites, including, CLC, Duckworks, Jamestown distributors and others. Try woodfinder.com as well.

Good luck!
Dave