I am the orignal owner of a 1990 H27 hunter sailboat.In the bilge I have several keel bolts. The two in the middle of the bilge are corroded as if they were regulariron steel. They should be stanless steel. Does anybody know if this was a defect when they built the boat in 1990 or any year? Does not leak through the bolts. What is the best way to fix them or should I just leave them alone because they are not leaking/seeping?