Ok new to this, last year my wife bought me a 1973 Thunderbird Boat. Went out this year and found the floor was soft in several places, have cut out the old plywood and fiberglass what is the best way to replace this? It appears that it was stored outside with nocover prior to me getting it, the plywood was very rotten in places. But there does not seem to be any strutural damage to the boat. Would like to fix, and restore it back to original if possible.