A boat that small is not likely documented.

You will need to transfer whatever ownership papers CA. uses for a boat- most
likely a title as in the majority of states.

Make sure the seller *has* a clear title, in his own name. It wouldn't be
ridiculous to
hold off closing the sale until after you have confirmed the title status.

What could go wrong with a deal where the seller hands you a title? Plenty.

The seller might have sold the same boat, to somebody else, last week. He may
have given them a title, too. This can happen when a seller swears out a false
affidavit of lost title (or whatever the form is called in CA) and obtains a
duplicate title.
Now has one boat, but two titles.

The seller may have hired a boat yard to do extensive work on the vessel, and
then stiffed them for the bill. If there's a mechanic's lien on the boat, you
will wind up paying whatever that amount might be (hope it isn't too large) if
you want to keep the boat. You might think you're buying a boat for $3500, but
when a yard shows up with a signed work order authorizing $4000 in unpaid
repairs on the same boat you can be out a lot more than you anticipated.

One of the downsides of dealing with a FSBO- they are only going to sell one
boat, not make a career out of it, so the few dishonest apples in the barrell
get away with a lot more than a closely watched broker ever could.

And, in these days of identity theft, I think it pays to make sure that Joe
Blow has some believable photo idea to show that he's the same name that
appears on the paperwork. If the guy stole the boat *and* the title, you would
have a tough time depriving the rightful owner of its return.