Not at all an uncommon issue w/older boats. Unless there's moisture damage to the bulkhead, this is caused by constant expansion/contraction of the bulkheads along with the boats regular use ie being sailed, pounding, rigging
stain on the chainplates.
Not a big deal real. As long as ur bulkheads are solid.... Just either shoot in some west systems 6-10 or mix up some epoxy
w/coloidial cylica spread it along the bulkhead. Then though bolt it w/stainless nuts, bolts and washers. Clean up any epoxy
that squeezes out and ur good to go.
Or u can spend a lot of time n money
stripping it all out and redo everything?!?!...