keel bolts can be checked by lifting inspection plates in the floor.....
Not really. You can only see the exposed part of the bolt. The bigger issue is what it looks like below the bilge and inside the keel. Iíve never known a survey to check this, which is why I would want to know if theyíre original.
In my case, we had a boat yard put rock salt in my bilge to try to melt ice that had formed. She went up on the hard, it poured rain and our keel stepped mast allows meaningful water in, especially when wind is toward the furling mast slot. The bilge drain (remove a through hull near the mast) hadnít been opened yet. Then, as luck would have it, the cold front that produced the rainstorm dropped temps way below freezing. It was a bad situation.
In any case, that dumbass rock salt move has caused severe corrosion on the nuts and threaded posts you can see. I have a strong suspicion, the threads below will be fine.
On the other hand, itís entirely possible that the nuts and threads in the bilge look fine, if theyíve been clean and dry for a lifetime. However, if the keel joint has leaked in the past 30 years, they could be corroded where you canít see. There may or may not be telltales of rust at this joint. It could have been cleaned up and sealed. Further itís possible the rust at the joint is just the iron keel, if it has one, and not the bolts. I know one of our members here has posted pics of his keel bolts, when he dropped his keel. They looked okay on top, but the parts below the bilge were half corroded away.
Iím not saying all boats need new keel boats in 14 years. Iím only saying itís a genuine wildcard on a 30+ year old boat, if theyíre original.