..................use a bit on a drill such as a counter sink to bevel out the visible part of the screw hole. if you don't bevel it out, you will see a line where the repair is. next, put some tape on the backside of the hole. then fill the hole nearly to the top (about a credit card's thickness shy) with some white Marine Tex or similar product. after it kicks, rough up the Marine Tex with some 100 grit sandpaper. using a wooden toothpick, fill the rest of the hole with Parker gelcoat to slightly above the top of the hole. next day or after it kicks, use a small sanding block about the size of a deck of card or smaller (make one out of any thing flat like a small piece of starboard) to wet sand the hole flush. the hole will disappear as it becomes flush. you can start out with 400, 600, 1000, 1500 then finish with 3M Finesse It II and finally some wax.
again the key to an invisible repair is the beveling. the new gelcoat has to overlap the freshly bevelled area.