[Zeke]

Sandpaper is a bigger subject than most people think it is. I would try to remove the paint w/o getting into the gel coat too much. This could be a remover of some sort, you have to experiment. Maybe a heat gun will get a lot of the paint off. I know gel coat will take quite a bit of heat before it bubbles.

After that go with the finer paper that works. 50 is rough. I do use a lot of 80 to begin with and I buy the D weight good stuff for my orbital (not random) Makita 1/4 sheet sander.