Anyone that owns a fiberglass boat will unfortunately at some point create a scratch, dig a gouge or put a chip into the gel coat. Gel coat is basically like hard paint that covers the fiberglass on the outside layer of your boat and this gives it that nice shiny finish. If this happens to you, don't worry, here is a way to repair that damage and make your boat look new again.
Start by grinding away the damaged and cracked existing gel coat, down to the fiberglass. Make sure to grind out the area past any of the visible cracks that may be there, as these can spread like a crack in your car’s windshield.
Clean the area with some acetone and use a heat light to dry and warm the area. Gel coat repair kits can be bought at most marinas and auto parts stores. You can also get matching gel coat from aftermarket companies or your boats manufacturer.
Use a clear repair paste and mix a little gel coat in with it to form a colored paste. I use a spoon as most of the repairs I do are small. Add about 8 to 10 drops of the hardener for every spoonful, (about 2%), to the paste, fill the ground out area and let it sit for a few hours to set up.
Use a course grit sandpaper to form the hardened gel paste, 50 or 80 grit works good to start. Once you get the shape back, move up to a 250 to 400 grit and fine tune the repair. Finish by wet sanding with 800 and then use a buffer with some compound to get the shine back.
If it's a flat surface, use a sanding block and for anything else, I like to cut a 9x11 piece of sandpaper in half then in half again. Fold the piece you have left the way it's shown in the pictures. This will give you a solid piece for sanding with and will help eliminate uneven sanding surfaces.
Gel coat repair is not hard, but the process does take some time. The main thing here is to cover the fiberglass so water does not get in between that and the gel coat and cause further damage down the road. Happy boating.