Heluse, it sounds like you didn't get the boat surveyed before you bought it. A haul out is required in that inspection. If it was sitting for a couple of years in the water, was the bottom kept clean? If not you are going to need it clean before you haul it out and have it inspected. On some older boats the keel will drop a fraction of an inch. It will cause what is known by many as the "Catalina Smile". A crack in the fiberglass around the front of the keel. I was told it was really nothing to worry about. But that was by a broker who was helping me buy my boat which was listed by another broker in his company. My 86 didn't have the smile, but the keel bolts are in salt water most of the time, see post on muffler, and have only small spots of rust on them. If yours are that bad I would haul the boat and among a lot of other things to do while it is out, replace the nuts, not sure how to torque the ones under the deck by the engine. Have all the through holes inspected while it is out as well as the cutlass bearing. Good time to replace the packing gland too with the non-leak kind. I love it, that is how I found my leaky muffler, all the time it thought it was the packing gland leaking. Just a lot of little stuff that can become BIG headaches if not maintained.