Re: Spider cracks in fiberglass.
If you decide to fix them, depending on the size,there are a few steps. If they are small, like smaller than a nickel..you would be best off sanding the whole crack out. Now it will make a divit of course, but easy to fix. You can either use a gel coat repair kit or fiberglass repair (like kitty hair but finer) to fill in. I like to leave a little more in than I need in case of shrinkage so when it dries I can d/a sand it smooth, then poly primer or the primer of your choice, and paint.
For bigger ones..say over the size of a quarter I like to take a small sharp drill bit..usually on a high speed dremel of sorts..and gently drill a small shallow hole at the end of the crack, this will relive the cracks stress (not the reason for the crack though) s it wont crack on further. Then same thing..skim coat of gel repair over the area, d/a smooth, primer, paint.
Sometimes hose cracks happen around screws because its older gel coat and a screw was moved or the hole wasnt predrilled, sometimes it can be from boat flex and thats where a hole was so its easy to crack (think windshield..small pebble crack turns into the length of the windshield a month later from movement of car).
