I only had two boats surveyed but each time it was post-purchase and sale contract
and each time the stipulation was "if the survey finds more than $X of new issues/problems, other than those observable by the buyer and/or disclosed by the seller". The first time, I was a real clueless newbie and my own inspection
obviously was worthless, the surveyor found a bunch of things wrong which he called "home depot-ing" the boat as the seller was a very handy high school
woodworking teacher and did very nice carpentry but totally non marine
otherwise. So the electrical
while very recent was house wire and fixtures and had to be totally replaced, some deck hardware
was improperly installed and had to be re-bedded and reinstalled, etc. There was over $10K worth of repairs
if done by the yard (probably under $6K if done by a moonlighting yard guy) so when the seller refused to knock off that much of the price
I walked getting my $500 deposit back instantly.
The second time my $X stipulation was $1000+ and the surveyor said there was nothing really wrong with the boat other than stuff which needs replacement due to its age (which echoed the conclusions of my two marine-pro friends) but that was already factored in the price as the asking price was about 1/2 of same models on the market at the time. Although all of them missed a thing or two which probably would have saved me a grand or two but as it was I was happy with the purchase
and in the long run splashing her in time to catch the rest of the season, as opposed to one more summer without a boat, was worth these few thousand bucks.