Enamel will work. Prep is very important. Before you start, scrub with dishwashing soap and water. Dry and degrease with a wax/greaser remover (don't use lacquer thinner). Scuff sand with 400. Don't sand through the gelcoat. Use a red Scrotch-Brite pad for those hard to get areas. Degrease again. Spray your favorite enamel.
I am about to repaint a fiberglass cap with a different color, old color is moroon and new color will be dark blue. Do I need to primer before painting color? I'm using acrylic enamel. Also there are a few small chips in it, can I fill with body filler or fiberglass resin? Thanks.