What is the best way to waterproof plywood before carpeting?

I'm gonna be adding a floor to my lowe 1240 jon boat. I would like to know ways to waterproof the plywood before putting carpet on it. Can I roll a few coats of polly on it? Whats does everyone recommend? I would like the floor to be removable...thanks for any help

I have had good success with just plain oil based enamel paint or oil based varnish.
first coat - 50/50 cut with mineral spirits or turpentine
second coat - 75% paint - 25% thinner
third coat - reduce the paint just 10%.
allow ample time for the paint to penetrate the wood and dry thoroughly before the next coat.
some people like to add 25-50% Boiled Linseed Oil to the mix as well.
any kind of oil based enamel paint is ok. paint both sides and all edges after
they have been cut to fit. fill any voids with exterior grade caulk.
when you purchase the carpet glue, read the directions very carefully.
some adhesives do not stick well to a painted surface. (especially latex paints).
do not use pressure treated wood that will come in contact with aluminum.
do not use 100% pure silicone on aluminum (it promotes corrosion).



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If you want the floor to be removeable, treat it as Johnny described, glue the carpet, then screw it down. Use stainless screws. With the heads exposed, you can remove it easily.

I pre-drilled the holes for screws after cutting plywood to fit. Then sealed with epoxy on both sides. It adds to the size of wood and small amount of weight.