Under the waterline paint? / gelcoat? / flowcoat?

I was talking to one of the guys at a store where go to get supplies for my boat I am working on and he said I could re apply gelcoat to the hull by using a roller? Can this be done? Gelcoat is too thick for that is it not?

 

Yes, it can be done. Sand the bottom really well, then apply gelcoat to the bottom. I suggest applying at least 2 layers, with the last layer some parafin added to it, so it cures without a sticky surface.

Then take a piece of sandpaper, and sand everything smooth. Use finer sandpapers, up to grit 1000 or finer, and polish up the bottom. It is a hell of a job, but it can be done.

Of course, under the waterline, you could also use any bottom paint of your liking.