[flybouy]

Be very cautious when using a heat gun, it's easy to blister the gel coat. Same can be said with any friction type pad, staying in spot too long can be disastrous. From years of previous boat ownership I used to see the marina use acetone but that was years ago so I'd think there might be a better product. If you have a marina nearby you may want to check with them as they deal with this every day.