Mid 1980s C&C keel issues

See below for photos of mid-80s C&C keel deterioration.  This appears to occur where winters are freezing cold and boats are stored on land.   Seems as though water migrates down the keelbolt into the lead casting and freezes each winter, incrementally enlarging any voids or cavities each seasonal cycle.  These photos were shot in a short stroll around one marina yard, near Toronto.