Found a Few Hairline Cracks in the Fiberglass Siding

These develop on almost every fiberglass vehicle or boat that flexes. On my boat, what I do is take a razor blade and etch a small circle at the tip of each gel coat stress crack. What this does is forces the crack to run back on itself. Filling in these stress cracks don't do much since its superficial. Purely cosmetic. I personally don't prefer the drill method because that becomes too invasive.