You don't indicate how old this boat is or whether it's got a swing or fixed keel. The entire boat needs to be gone over, but I offer the following specific items (from my own experience as an owner of a 1976 C-22). If it has a swing keel, you need to check the bolts attaching the keel to the hull. You also need to check the keel
winch system (winch, cable, attachment of cable to keel). The hose pipe and clamp(s) that attach to the "cone" where the cable enters and exits the hull needs to be checked for leakage, age, wear, etc. I'd also check the
lights (running and steaming), particularly where it plugs into the deck.