I'm an experienced business lawyer. I understand contingencies in a P&S.
No matter. It's not worth the effort to enter into protracted price negotiations after a survey has revealed significant defects in a boat.
You are paying for the survey in either case, aren't you?
If you think enough of the boat to seriously consider an offer, a survey before making the offer costs you nothing, since once you make the offer, you are committed to hiring a surveyor anyway.
Also, getting the survey up front allows me to take all of the significant defects into account up front. If I still like the boat enough to make an offer, I will make the appropriate price adjustments then. I'm not going to get stuck with an uncompensated problem in any event.
That's the way its done in business-- a non bindling letter of intent followed by due diligence, and if the diligence is acceptable, then a P&S with appropriate closing conditions. The residential real estate model, where the P&S is signed first, is far too advantageous for the seller, for whom the brokers work (as do yacht brokers).