In the case of an absolute auction...
it's up to bidders to know what they're bidding on BEFORE they place a bid. No matter what the item--whether it's boat or a Ming vase--you won't find ANY auctioneer, not even Sotheby's or Christie's, who'll accept a bid that's contingent on appraisal after the sale. If a bidder feels he needs a survey, he has to have it done before he places a bid. Only if an item, say a supposed genuine Picasso, turns out not to be does a buyer have any recourse after he's bought it auction. As long as it's as represented--a genuine Picasso--if he had to bid $2 mil. to get it and it turns out to be worth only $1.5, that's the breaks...he should have had it appraised before he bid on it. Boats are no different. At least in this case, it's local to John, so he can inspect it himself or with a surveyor.