On commander #138 the fiberglass was worn away down to the wood. The wood was in good shape, so instead of glassing it in, I used my favorite all time boat stuff (since buying a boat) Over the wood ( i chiseled out a small rotten area) I applied Interprotect Watertite, a 2 part epoxy. I love the stuff, it is waterproof. Just let it dry, sand it and paint it. it is designed for gel coat blister repair, but can be applied up to 3/4? of an inch. My motor mount where I used it has been great, no problems and that was 2 season ago. Incidently, proper repair of the drain hole there is VERY important, that is how the water can get into the wood as well. ( I dried it with a blower dryer for several days, then used my favorite stuff to epoxy in a rubber tube cut flush, epoxy and painted the ends of the tube in place. where the tube exits the fiberglass. I did not dry it long enought the 1st time becasue water eventually pushed its way out around the tub. You need to do this after a haulout. Good luck