The only way to inspect the keel bolts is from under the boat, usually with the boat out of the water. I have an 84 swinger that I bought last year. First order of business was to replace the lifting winch, turning ball, cable, volcano tube and keel bolts so that I would have a point of reference as to when the necessary maintenance needed to be done. Catalinadirect.com sells all the replacement parts you need to do all this.
I own a 1982 25' catalina, swing keel. I bought it from the original owner. He has had it on the same lake (Ray Roberts in Texas) since new. It is in good shape and never in salt water. I'm not sure if the keel bolt has ever been inspected or changed out. I removed the cover in the cockpit to reveal an enclosed fiber glass cover over what I think is the keel bolt housing. Can you tell me if this is the best access to inspect and possibly change the keel bolt. Or is there another way to inspect and ensure the keel bolt fails and my keel (or boat) doesn't go crashing into the depths of the lake/ Thanks for you assistance tom