As long as the surrounding material, either wood, fiberglass, or even steel, is solid and cleaned with acetone it should stick well with epoxy. I restored a 1959 SlickCraft 16' Premeire in 2009 that had a 1980s fiberglass patch on the molded plywood bottom that was as solid as ever when I found it.
Interesting. I just fiberglassed rust holes. Never tried it on wood. Looks like a good solid repair.
As long as the surrounding material, either wood, fiberglass, or even steel, is solid and cleaned with acetone it should stick well with epoxy. I restored a 1959 SlickCraft 16' Premeire in 2009 that had a 1980s fiberglass patch on the molded plywood bottom that was as solid as ever when I found it.