It is a miracle!
Just apply OVEN OFF oven cleaner. The warmer the temps the better. Just spray it on and let it set for 5-10 mins. Then using a deck brush you can scrub it off. It may take two-three applications depending on the build up. Rinse with water between applications. When you think that the oven off is not going to remove any more paint you can take some acetone on a rag (DO NOT APPLY DIRECTLY TO THE GELCOAT) and clean up the remaining spots. They you can use some rubbing compound or some good wax/polish to clean it up. If you are not in a hurry, you should leave the area exposed to the sun to bleach out the area as much as possible. The area where the old paint was tends to be yellowish. The sun will help to equalize the color. This method is recommended by most of the sign painters.
