NO,NO,NO. Sorry for shouting. Fiberglass over wood is a sure- fire way for the wood(timber or ply) to die early. Polyester resins are not vapor proof and moisture gets trapped behind the layer of glass and has a gay time rotting your wood. Also the expansion is different between the two mediums. If you have plywood then use epoxy/glass only and WEST the whole works. My experience?? Oh yeah, I bought a Wharram Cat many years ago with polyester and a six ounce layer of fiberglass over it. It looked good until the glass came off in great sheets to expose the ply which was just about totally gone in same areas. Uwe R.