Probably nothing.
I've done keel repairs three times now. The last one was caused while I slowly moved toward a mooring float. I didn't realize that it was attached to a huge concrete block in shallow water. That put a gouge in the keel locking bolt holes No wonder all the boats there were motorboats! You can repair it from inside the boat, but be prepared to exert much energy and do much cussing. Basically, you have to place something solid behind the area that needs repair. If the gouge is long enough, you can slip a piece of flat metal attached to a long bolt and nut through the gouge. This will require much imagination and inventiveness. You will pack that damaged area with shreaded fiberglass mixed with epoxy. The consistency would be almost like putty. You don't have to buy special cut-up fiberglass. Just get a small piece and use sissors to make 1/8 inch cuts. Approximately 1/4 cup worth should do. Use a paper or plastic cup and disposable plastic knife or wooden stick to mix the epoxy in. After the area is packed, slowly unscrew that bolt and nut, allowing whatever you used as a backing to fall to the ground. Unless absolutely necessary, don't touch that new material for a day. Returning the following day, get a proper sized drill and bit and "dress" the hole. There should be something left of the original hole's radius that you can use as a guide. Perhaps you should place grease pencil markings (X marks the center) prior to doing the repair. If the hole looks good, all that is left is to sand the trunk to assure a good seal of the rubber gasket. Easier said than done: You can use a small grind stone on your drill,or use a piece of wood with sandpaper and turn it round and round by hand. That's when the cussing starts! When it's all done, and you're satisfied, you then get to do the really difficult one INSIDE the battery hold-down area. At least with that one, you can use a regular sanding block to assure a good gasket seal. Hint: Any backing for the new material pack can be held in position by pushing a long bolt, screwdriver, rod, wooden dowel, anything you can dream-up, to hold whatever backing you are able to use in position by pushing from the other hole. Or...you can throw you hands up and have a marina drop you keel and do the repair in a more professional manner. Me....I'm to cheap to pay someone for something I can do, regardless of how dirty or difficult it may be. Besides, you'll become more intimate with the construction of your boat by doing your own work. The second time you do repairs on your boat will be much easier. You'll learn many tricks and techniques from doing it that difficult first time. Remember, the most important tool for this repair is your imagination. Hint: The epoxi you buy should be the type that comes in two small disposable syringes. Buy two kits: one for each side. Hint: Use rubber gloves or you'll have a sticky mess all over your repair area. Get a box full from the pharmacy. Hint: Have a roll of paper towels handy. You'll need them.
