Or you could do it my way – my #1 boat is 20 years old, and has thin gelcoat. I have a couple of scratches on it that went all the way to the layup along the chine, so I decided to have some fun – sand the area around the scratch with very light sandpaper (By hand), re-gelcoat the area, and sand it flush (Once again by hand). Difference with mine is that I added no color to the gelcoat – it looks like it has holes in it when I carry it in the sun. Nobody has ever commented on it, but then again, it looked like that before I did the repair.
I really did this. I have a weird sense of humor.
The Connyak BBS