Re: Plywood choices
Use ACX plywood. That is, exterior plywood with an 'A' side (a good looking side) and a 'C' side (not so good looking side). When you buy it, take your time and look at the edges to make sure there are no visible voids there. ACX usually has voids on the interior, but if you can't see any on the edges, it's a good bet the rest doesn't have many either. <br /><br />Since you are only talking about decking, stress on the wood isn't an issue, I assume. So, ACX should be just fine. If is a stress area (such as the transom, or you are going to 'torture' plywood (i.e. bend it) then ACX with voids might be a problem if there's a void where you are bending.<br /><br />Usually three coats or so of epoxy will make it waterproof, but ACX will 'check' (i.e. hairline cracks that form in cheaper plywood over time) and this will break through the epoxy. If you fiberglass the outside, you won't have to worry about that. <br /><br />I'm using 4oz fiberglass cloth for that. Now, that doesn't add strength, but will prevent checking from becoming a problem. I just lay the cloth out and wet it out with epoxy and then put a second coat on that. The final coat is the fairing coat to get rid of the weave. 4oz cloth doesn't soak up much epoxy either. <br /><br />Good luck!
