[Ronbo]

Remove the gelcoat, three good heavy coats of Dupont 2-part epoxy primer. No cracks in 10+ years on my Corvette. Always use vinyl ester fillers not polyester (cheap crap like Bondo). The polyester shrinks over about 6 months (found this out the hard way).

Also make sure everything, and I mean everything, is isolation mounted with rubber. (mirrors, emblems, ect)

Gel coat sucks.