Don't need to repaint entire boat, but I have a few areas where paint has been scratched off and, in a couple of these areas, has a blistered appearence. What is the procedure for removing this without risking sanding through fiberglass, in order to repaint. Do you just use a very fine grained sandpaper, or do you use something other than sandpaper to remove older blistered paint?

Thanks,
Dave Walker