Fixing cracks, scratches, and chinks in fiberglass is a pretty easy process which often doesn’t work out too well. It should be simple, right? Just mix the resin and hardener, add a little pigment, and smear it on. Well… sort of. If you have something you need to fix on your boat, give this a quick read-through before you get started – it could make the difference between a clean looking repair job, and making your boat look worse than it did when you got started.
One big mistake people make is doing the repair in the evening, after work. This is a bad move because as the sun goes down the temperature changes rapidly; that changes the rate at which the gel coat hardens. You can end up with a dry outside but a gooey inside, which never really sets properly.
Another bad move is adding the hardener to the gel coat before mixing in the pigment. It can take a few tries to get the color match right, and if you add the hardener first, it’ll become tougher and tougher to thoroughly mix while you add the pigment.
Botching the job also happens when people put on the gel coat, and leave it completely exposed to the air. Gel coat hardens more uniformly if you cover the repair with plastic wrap or a similar film, as it dries.
Another gel coat no-no is painting it on with a brush. Sometimes this works out okay, but other times the brush strokes remain in the finished product. Generally speaking, a plastic resin spreader works best.
When filling cracks in a horizontal surface, never walk away from the job before it has a chance to soak in. Deck cracks, in particular, may swallow up gel coat before it has a chance to harden. Whenever you’r working on a horizontal surface give it a check every 15 minutes, for the first hour or two, and add more gel coat as necessary. Follow the manufacturer’s instructions and look out for these common mistakes, and your gel coat repair should come out just fine. Fail to do so, and you might regret you started this project in the first place.