Paint no matter what kind isn't going to stand up to the beach. I painted a Hobie 18 I used to have with Imron and before I did I taped off about a four inch wide strip tapered down at the front and left that gelcoat. The Gelcoat is much easier to repair and work with. If your going to sand anyway you might as well try sanding and polishing first.

Another way to do this would be to sand to about 280 and have the boat clearcoated with Imron or Awlgrip. This works really good on colored hulls. Nice thing is if get it scratched the old color dosen't show through.