Assume a seller lists his boat
with a broker and the broker presents an asking price offer from a
buyer. If the seller changes his mind to sell, is the broker due his
commission as if the boat sold?



You could make a case that if a broker brings a full price offer, without any
contingencies for financing, survey, etc, and the seller then said, "Sorry, but
I've decided to keep the boat after all," the broker would be due a commission.

The weasel out for the seller is that almost no offers are full price and
without contingencies. If the buyer offers 99% of asking price, there is
nothing that compells the seller to discount the boat 1% if he has changed his
mind about selling. Same with sea trial, survey, etc.
Nothing says the seller *must* allow you to sea trial or survey the boat. The
seller can say no to the discount, no to allowing a survey, no to accepting an
offer subject to finanacing, no to a sea trial, etc.