A buddy of mine is in the boat repair biz. and when my work is slow I help him some times. I've done some floors with him and we cut the plywood to size, put resin on the bottom and edges, wait for it to set up and then we screw it down ( counter sinking the screws ) and glass over it. Depending on the application we will use 5200 on the top of the stringers before we screw it down but if you space the screws at about 3 or 4 inches it shouldn't be that necessary. Once we did a 25' stieger craft or Parker I don't remember, but and I was amazed to see that they just nailed the deck down with galvanized spiral nails, no glue. The boat was at least 10 years old and the reason the deck went bad was that it was stored for years with the bow down and water and ice was always pooling up against the pilot house. Other wise it would still be good today. So this is the other extreme but it worked for them.