Step 4: Grind Down the Deck Around the Break
I used a disk sander with a 50grit disk and a backing pad to feather down the fiberglass skin all around the break. You need to make room for the new fiberglass or you'll have a bulge over the break. That would be fine on the deck actually, but you wouldn't want it on the bottom of the board.
Use a light touch and good concentration. This tool cuts fast.