We recently received a 74 Sunfish that had been in storage for 20 plus years. The price (free) was good, but some problems ahve cropped up that are maybe beyond us. The main one is a hole along the keel that had been patched with caulking and then covered with some sort of black resin. We've sanded off most of the resin to expose the hole -- about 1" x 2". The wood is gone.This is all new to us. Any suggestions. Some sort of sceening, then fiberglas?