Oday 22- good boat-
Since these boats are inexpensive, look for the things that will cost the most-
Outboard- make sure it starts, and idles after it has warmed up. it should idle so slowly it's almost quiet- that's the speed you'll want to be moving when you approach a dock!
Rigging- this is what holds the mast up. Check that the mast doesn't lean left or right- and that the tension on both sides feels the same. When the chainplates leak, the boat's body will flex a little bit, and this is big trouble. Then check how the mast leans, from front to back. It should have a little flex backwards, or at worst, straight. If it looks like it leans a little forward, it won't sail worth a hoot, and you may have rotting in the transom.. again, big issues. Also, run you fingers on those wires- they should be smooth. If you get a snag, or feel rust, you MUST replace, for safety. $$$
Sails- since this is you first sailboat (a great starter boat, by the way), all you need to worry about is that they're not ripped, no sailtape (torn sails can be taped to stop further ripping), and they should feel starched, almost crunchy. If not, it's still usable, but they cost $$$ to replace.
Others have said look for soft spots- this is when water has leaked in, and rotted the wood core. Fixable, but not for a newbie, and not what you want to take on for your first boat. Some spots are more important than others- a soft spot in the middle of the deck isn't too big a deal. A soft spot where the standing rigging connects to the deck- run quickly.
The centerboard is raised and lowered with a line, and the weight isn't much. Just make sure it is attached. Sometimes the board won't lower, as barnacles have jammed the board up there. I've actually stuck a 4' piece of thin rebar where the line comes out into the cockpit, and freed the board that way... a couple of times

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Check the bilge for water. small amounts usually mean leaks around ports and such. That slight mildew smell will confirm. Not a big deal, but if there's alot of water in there, and it hasn't been raining cats and dogs for 2 weeks, you may have an actual leak, and only the flotation keeps it from flooding...
The boat has a decent layout- the head is behind a door, and there's lots of room below, but that's at the expense of the cockpit, which I think is only comfy for about 3, maybe 4 max. Since most of our time is spent in the cockpit, I wish it were bigger (longer). Other than that, nice.
The fresh water system is a pump sink and a container, and that's it. The electrical is simple. I'd check that the lights work, particularly on the mast. Most have 2 sets of wires that exit the mast at the bottom, and connect to ONE power wire. You have to choose which light you want on, steaming or anchor. I'd make sure they both work, and hold the owner responsible for that. You really don't climb a mast like that, you take it down to fix things. It's stressful the first few times!
Good luck with your boat, and remember the help you can get from the guys here. The're invaluable, and free. And worth way more!
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