scarf the joint at 12-1, roughed up for a mechanical bond and chemically clean - they follow the same lay up schedule with fiberglass including resin to glass percentage (don't want a hard spot) smooth it back out, inside
paint if desired - gelcoat if visable. Outside is same, but fair the hull. Then grind, prep,
paint.
If the only thing you understood was grind, prep,
paint - hire someone ormake sure you have a PFD on when testing.