That's all true for certain consumer products although a horrible strategy for most. However, not for a boat yard. If a yard is building a boat at a loss, you the buyer are in trouble. Guaranteed. Every time I've ever seen this course pursued, the lack of funds along the way has become critical.
I have seen this happen dozens of times on construction projects during my career. The low bidder (significantly lower) gets the contract. Then he tries to cut corners, drags his feet when a better job comes along, change orders the client to death and if he really gets in trouble- goes bust.
But I don't know how to avoid it. Sometimes you can get a good price from someone who has a hole in his backlog, wants to break into a new market, or makes a mistake in his bidding. It all happens. If its the first two reasons, well he knows what he is getting into. The third, well not so good for anyone.
It takes guts to turn down a bid 25% lower than the others, and isn't done very often in my experience.
David