I replaced the decking and carpet in my previous boat about 4 years ago. Couldn't find marine grade plywood locally so I used cabinet grade instead. Cabinet grade has no interior or exterior voids to trap water. After cutting it to size I used two coats of epoxy resin from west marine to seal top, bottom and edges. I used contact cement to glue down on both the wood and aluminum decking. When I sold the boat a year ago it was all looking good.

Make sure you get enough carpet. It took a total of 27' to do my 17' boat allowing for cuts for compartment lids.