Bristol 24 ballast
Found a concrete engineer to discuss treating the ballast, and he suggested the first step would be take a 2" core of the ballast to see what is in there. This could be done from the top without much damage if a boring machine would fit down through the companionway. The hole could easily be glassed over. My bilge is about 10-3/4" deep at the aft end, but some white residue similar to concrete has leaked from a couple of small blisters on the hull down in the ballast area. Possibly I have lead encapsulated in concrete.
Bristol 24 "Banoo" Hull #576