there is not alot that can go wrong with a catalina
25 that would need an outside inspection.. for 5k it an older 25 if I'm right.. the only major concern is if its a swing keel
model and the pivot pin for the keel
.. they can wobble out and have to be repaired.. and you should be getting a trailer with the boat to haul it out on..
If not, losen up the locking pin on the keel and rase it about half way with the winch
.. go in the water
and grab the rear of the keel and try to shake it or move it from side to side. if its sloppy and moves around, it might be a concern, but if its tight, no worries............
If its a fixed keel, disreguard all above info and go sailing...........
If the boat is in the marina, as a few people how the guy has treated the boat, and just have a basic look around.. if the boat is clean and tidey and looks like its been taken care of, little damage to the rails, its probablly a good boat..
But if you see the rub rails and the deck
cracked at the sides, he's probably done a share of busting the boat up.. stay away from it..
Another good sorce, call "Catalina Direct" out of Sacramento and ask them what to look for when buying
.. Great people and will have all the asessories you can think of for the boat