This experience only proves to demonstrate
the importance of making any offer "subject to survey and sea trial," and the even greater importance of paying for a full pre-purchase survey, done for buyer by a surveyor hired by and working for the buyer. A seller is under no obligation to disclose anything...a survey done for a seller is worthless to a buyer...and a survey done after the deal is closed isn't likely to provide any recourse against a seller unless it can be proven that the seller lied. Proving that can be very difficult unless you can also prove that the seller is knowledgable enough to have known that work that he claimed to have been told, or believed, that was done properly wasn't. As for any recourse against the seller's surveyor, only if the seller joins you in the claim...because that surveyor was working for him, not you. Unfortunately, when it comes to buying a boat, CAVEAT EMPTOR rules. Even more unfortunately, you're not the first, and won't be the last, boat buyer for whom learning that turned out to be very expensive. I sincerely hope that there's a loophole in the wording of the Bill of Sale, or witnesses to your conversations with the seller that will allow a good lawyer to cut the cost of your education without adding even more to the cost of it. I wouldn't count on it, though.