I think the gelcoat is too thin to sand and not get into the flakes. Ive decided to recoat and have done urethane clear on a few boats in the past, but I'm leary of clouding on this one. The others I've sprayed turned out good, but it was the owners that wanted urethane clear to get the boat back quickly.Have you tried wet sanding, rubbing compound, and polish. Depending on the condition of the paint/gel coat