[DanEC]

With fiberglass topped with gelcoat and paint - after the hole has been carefully drilled to final size in a series of steps of increasing diameter - I typically take a larger bit and run it backwards to put a pretty good camfer at the top of the hole through the paint and gelcoat. This helps prevent lifting of the gelcoat and paint as the screw is threaded in. The threads on the screw try to lift the gelcoat off of the body as it's run in - thus the chamfer.

Also, I have found you have to drill the hole sufficiently large to prevent the screw from siezing up as you try to run it in, as that will start lifting gelcoat and paint. If the screw starts to get tight while running it in, pull out and drill one more size larger. You can't just force a screw into fiberglass like you might metal or aluminum plate.