Im looking to repair a couple of gouges that apparently occured during my winter layup, and the marina has no idea how it happened.. Anyways, Im a little hesitant to take sand paper to my nice shiny gel coat after applying the repair. Does anyone know what would be the correct steps of sandpaper grit to make sure that i have a level, clean, and most of all, shiny finish? The repairs are in the white so I don't need to do any color tinting..