Holes in any boat may look bad, but unless there is structural damage, fiberglass is pretty easy to patch. You can get a fiberglass repair kit at any marine store and gel coat to match your boat from your boat’s manufacturer.
Let’s get to it. First, you grind the edges of the hole so that the fiberglass around it is exposed. You’ll need to taper the hole so that the outside edge is about two inches wider than the inside edge. When you are finished sanding, wipe all of the dust away.
Now you want to contour your patch to match the shape of the hull, so cut some cardboard about two inches wider than the hole. Cover it with plastic wrap so your patch won’t stick. Place it inside the hull. Bend the cardboard to match the shape of the hull. Tape it into place with masking tape. Now your hole is backed.
Cut your first layer of roving to fit inside the smallest part of the hole. Cut your next layers larger and larger to overlap each previous layer. When you have placed enough layers so that you are level with the hull surface, cut and place your fiberglass cloth on top.
Apply the resin as directed. Center the smallest piece of roving into your prepared hole in the hull. Repeat with the next smallest patch and so on. Once you have applied all the layers, place a dry fiberglass cloth on top of the resin-soaked roving.
Let the patch dry as directed, and then remove the cardboard backing and sand patch. Then all that is left is painting!