Why protect Fiberglass?
Too many times I have seen a half decently made #fiberglass repair only to find it beginning to rot. When repairing both under and above the waterline what ever you use will need to be protected. It isn’t simply enough to make a composite repair both above or below the waterline only then to leave it unprotected. UV will degrade your repair both above and below. Saltwater will also degrade repairs and freshwater pools. And in both cases little underwater creatures will also help advance the processes of degradation. Eventually all of these factors will lead to delamination and then failure to the exposed fiberglass. Your choices of protection are simple: epoxy primers, barrier coats, marine paints and or Gel coat. When the repair is under water anti-fouling only covers and hides the damaged area but does absolutely nothing to protect it. As a matter of fact, anti-fouling is porous and only serves to hide the degradation taking place on your new repair. Oddly enough I seem to meet a lot of boat repair experts and professionals who don’t seem to know this. So this is a call out to all sailors and boat owners. Make sure that the repair is properly protected. If you didn’t do the repair, ask. If you are not sure of the answer, check for yourself. Lightly sand it or scratch it with a knife and look underneath the anti-fouling. If you see glass, they lied. If you see paint (normally grey, white or black), you’re good.