To my point, it makes no sense to have to make offers in the blind, and then pay someone to tell you you need to walk away from this one. The non disclosure on the part of sellers/brokers, IMO, borders on fraudulent behavior.
Okay, so I was right back when I asked if your complaint was that the seller didn't tell you about this. Some sellers, as has been mentioned, really are LMDs, just like in the subject line of this thread. Seems maybe you ran into one.
Some will tell you what they know about what is wrong with a boat. Whether they tell you or not, though, it is still caveat emptor.
Some on this forum have suggested that you ask the seller to sign a statement saying that he/she has disclosed all known defects. Can't hurt to ask, but even if you do, it is STILL incumbent on you to make your own inspection and maybe pay a surveyor. The seller might actually not know about a defect, or he might (gasp!) lie about not knowing.
In any case, this is certainly not backwards from the way other big-ticket items are sold. It is, in fact, exactly the same as the way other big-ticket items are sold. I don't think we're missing each other on this so much as you seem to be expecting something that is just unrealistic. That is, that you should never have to hire a surveyor, because the seller will always know everything that is wrong with his boat, how much repairs will cost, and will be absolutely honest about telling you all of this.
And if I'm wrong, and you actually aren't hoping for this unrealistic scenario, then I do not understand how you can consider it unreasonable or "backwards" to hire a surveyor to help you with your due diligence. The whole process just seems perfectly natural and proper to me exactly the way it is.