An acrylic paint like AwlCraft or AlexSeal will allow you to repair the coating without too much difficulty and without swirl marks. As stated previously in some posts the true poly-urethanes like AwlGrip are nearly impossible to repair without swirl marks because of the "shell" that they have on the outside of the finish when they cure.

A product to consider, especially for rudders and boards, is Interlux Performance Epoxy. Its a really tough epoxy paint with teflon additive. Wet sands to a very slippery finish, can be repaired easily. Buffs out to a pretty nice shine, though not as shiny as a topcoat paint. Basically it gets you the repairability of gelcoat with the hardness of epoxy. Great stuff. If I re-finished my boat thats what I'd use.