Haul it and clean it. If there's that much growth on the bottom, you don't know what its done to the keel. Those beasties have a habit of getting into cracks, especially where the keel attaches to the hull, and as they grow, they expand weakening the joint and stripping the keel bolts. It's amazing how much power they have. Also, look for clogged thru hulls. By the way, I clean my own bottom, and there is a suction cup device with a handle that you push onto the hull and hang on to while using your other hand to clean.