I recently sold a yacht and used CHAPS. It works well if the purchaser is happy to come look, go away set up the transfer, it take place, then come back. (By which time the boat COULD have been moved etc so they potentially loose their money, if you as the seller are bent)
Bank Draft is fine if you can get to a boat, inspect it negotiate then go to the bank (most of us do this sort of thing on a Saturday and yes they still close at 12:30!!!)
I took a bank draft with me ( for 80% of the advertised cost) and a wad of cash to buy 7up, along with my driving license as a proof of id and address so that the seller could come after me if I wasn't legit. We both agreed that this was fair before hand as I had a 400 mile round trip and wanted to take the boat with me if she was what I wanted.
I suggested to the bank that they offer an internet service for people to 'check' the authentisity of the draft, to which I got the response "Have a nice day" only in that strange accent associated with bank call centres ....