West Systems 105 epoxy and 205 fast hardener. Roughen the area with some 220 grit sand paper, blot on some epoxy with a chip brush, wrap in fiberglass. Repeat until you have 2-4 layers of fiberglass. Use epoxy with 406 high-density filler to blend the edges if desired. Vacuum bag it until the epoxy has cured. Wet sand smooth if necessary, working up to 4000 grit.