I hit a submerged rock on a surf landing and lost some white gel coat on my QCC 400. There are 3 missing patches of gel coat, about 1" by 2". You can see the fiberglass but it looks undamaged. It leaks a little now, about 3 cups of water after 2 hours of paddling. What should I use to repair the damage, brand name of gel coat, and how do I do the repair? Thanks in advance.