Re: Construction questions for a Ranger 26
The Ragner26 had a good reputation, but it sounds like what you are buying is a fiberglass hull which will need complete refitting. The bulkheads, etc. are plywood, and once they take moisture damage the only fix is to toally remove them and replace them, and that's a bigger carpentry project than most folks want to get into. If you really enjoy large cabinet-grade structural jobs...by all means. Of course, first you have to send away for marine grade plywood because it just isn't commonly found.
Corroded keel bolts? IIRC the R26 has conventional "cast in the lead" J-bolts. If the nuts on top are corroded they can be replaced. If the bolts themselves are corroded, now you have to drill into the lead keel and sink new ones--another non-trivial task. And possibly jack the boat, lower the keel, rebed the whole thing.
The deck is probably cored, with a wood core of some type between the exterior layers of fiberglass. If that's damp, the typical fix is to slice off one side, install a whole new core, rebuild the deck...You may be getting the idea this is not quick or cheap.
Sounds like a boat that was neglected and abused, bought by some poor soul who had no idea what he was getting into, who is now looking to dump it on someone else. The general advice in this situation is, as Monty Python said:
RUN AWAY! RUN AWAY!
Unless you want to start a ships' carpentry school with some apprentices and spend a year of your free time and ten or twelve grand on the repairs.