At Keowee sailing club we have had the same helms 24 sink at the dock twice. Getting it back to the suface cost the guy 2500.00 each time but the process wasn't too difficult. The groups sent down three divers who attached large deflated innertubes to the bow and stern(like 5 or 6 each) these were inflated via surface air compressor to get(and keep) the boat upright. Next the divers made sure that all the hatches were closed and placed the companionway boards in leaving a gap for a compresor hose. they started adding air to the interior, slowly displacing a large amount of the water. after several hours the boat was floating level with the surface. now more pumps were working to get the water out. the keel wasn't an issue for them. I've seen it work flawlessly twice.

Always borrow money from a pessimist. He won't expect it back.