Boat Deck Replacement (Bass Boat)

[MMPikefork]

I have replaced the stringers foam and deck and now I am at the stage to fiberglass the deck surface. On average, how many plys of fiberglass should I use? I replace the deck with 1/2 pressure treated ply with one layer of fiberglass on the bottom separating it form the foam. Wouldn?t one layer of mat be sufficent enough at this stage? In this case, I would say it is just to water proofing ply. Note: Its amazing how strong the deck is with solid stringers and foam.
(1985 17 foot Astroglass Bass Boat)