Re: Painting right over gelcoat, no sanding necessary
gel coat is just thickened and pigmented polyester/fiberglass resin.
Easy to paint. But the real issue is UV damage which has broken down the resin and make for a chalking - porous - not good bonding surface. The fix is a solvent thinned eopxy primer like esp 155 which will firm up the surface and provide a good, fresh bonding surface.