kotzebuecdory-
Sorry to hear about your hull! There are at least three ways to handle this:
1. Take it back to the factory or a local marine shop that can do a professional job on it. They'll use original gel coat material and a procedure that will make it virtually impossible to see that there's been any damage or repair to the boat. This is the most expensive alternative, but preserves your investment best, especially if it's a relatively new boat.
2. Look up "gel coat repair" with Google and read several articles about the procedure. Depending on your skill level and whether you have a few tools available, determine if the Do It Yourself mode might work for you. This procedure requires some skill and experience in wording with fiberglass and / or paints. Contact the factory for the matching original color of gel coat material needed.
3. A simpler Do It Yourself method would be to carefully fill in the missing voids with Marinetex epoxy based fiberglass filler, a first class Bondo like product for marine use. The voids need to be carefully filled until level and sanded flat. Best to do this in several applications to not overfill too much and cause problems getting it back to level as the Marinetex is very hard to sand once it gets hard. If you've done body work on cars and are experienced, you may be willing to try this approach. The color can be matched by tinting the appliance white Marinetex down with a universal color match system to match the off-white hull. Alternately, the area can be sprayed with epoxy paint of a matching color, fogging it in near the edges, then, after throughly hardening, wet sanding it out with very fine wet/dry sandpaper and final polishing.
Others may have another alternative for you, but those are some to consider for now! Good Luck! Joe.