I woulk like to take a shot at this.
I am in a process of buying a boat, and thinking of buying new. But with my pass expericence, when buying use cars. Anything that cost more than $3,000.00, I would take it to a mechanic and have them look over. I would not ask a seller the reason why he or she is selling it, because 9 out of 10 times they would lie.
If I know nothing about boat, I would not go out and buy a use one that cost a lot of money with no one helping. That is a problem with buying use, as soon as money is changed hand, you own it. No warranty, no nothing. There was no written contract of the boat has to be in good condition. The buyer tested the boat, the buyer liked it, the buyer bought it.
It is a very expensive lesson that we all learned once in a life time. Do not assume of anything, take it to a mechanic before buying it. It doesn't cost that much for the mechanic to test and look for problem in a boat.