i just had my keel bolts replaced on the boat i bought. the survey caught it and the owner paid to have it repaired before i bought the boat.
in my case the ground plate failed and caused electrolysis to corrode the bolts. the ground plate was also replaced when the keel bolts were replaced.
it was a major undertaking, but luckily one i did not really have to deal with. this could have easily been avoided if the ground plate was checked often. a better sump pump placement would have also helped, i have fixed that problem.
Kirie Elite 29 CB