Sigh, so it looks like the cement in the keel dried unevenly and it cracked down the entire length, the good news is it stuck to the metal weights and fiberglass hull so that can be the positive. I don’t have any pics but the repair process has been to dig as much back out as I could then drive the crack apart and pour thin epoxy in, leave for 20 mins for it it be absorbed into the mortar then pour in slightly thickened epoxy. When I removed the wedges it squirted back out the gap which should mean that it’s going to solve the problem if not… It’s weight removal and start from scratch… Damn it!