Black Fun had galv bolts (3 x M20 transverse/horizontal bolts/nuts holding keel fin into socket)
After 10 years I hit them with some WD40, overtightened them weekly for 3 weeks to crack any adhesion to the hull then backed them off and tapped them out and they were mint. Had been quite wet from time to time too. Galv on galv tho - the internals of the keel fin were galv steam pipe, macrocarpa, carbon foil over.
Even after cutting around the socket the keel still wouldn't fall off even when hung from hiab and big, big hammer whacks. So it was sabre-saw time... and off she came.
Gue