My Bristol has a seacock on top of the CB trunk aft. You take the plug out of the seacock and screw in a threaded aluminum tube with a large piece of dowel in it. Then you open the seacock and can bang on the end of the dowel to free the CB. Never actually had to do this, but it seemed like an elegant solution provided by the builder. No problem doing it with the boat in the water if need be. Perhaps you have something similar or should install one.
Finished the circumnavigation in early February in Grenada. Have to work on a book project for the next several months so the boat will be waiting for next year.