You are probably better off doing spot repairs to the holes. Use epoxy mixed with a high density filler like colloidal silica and finish with gelcoat. Make sure you keep the excess absolutely cleaned off between applications or you will end up with a big mess. West Systems produce some good literature, suggest you study first! You can probably get the original gel from Formula. The repair will not look perfect but the alternative is to sand fairly large areas around the repair and blend the gelcoat which is beyond the scope of most do-it-yourselfers.
