X Doors Gelcoat

I am sure there is something on this site somewhere, but I have tried to search all over. Can someone point me to the best way to do minor repairs to the gelcoat on a set of x doors. In some places, the gealcoat is gone and it is to the fibers in the door. I know if the coat is not repaired, the paint will just soak into the fibers and never give a proper finish. For ease, I was thinking of just using an epoxy and then sanding it smooth, but there is probably a correct, easy way to do this economically.

I was looking at surfboard repair kits, though I have not tried it yet.

Any boating shop will have gelcoat repair kits. They are easy to use and relatively cheap. I think most automotive parts stores carry them as well.