Another factor is the lack of available bank loans for older boats such as ours. They don't qualify as collateral, so that restricts to a credit union or other personal loan source, or cash.
Financing therefore limits the market for 30-year-old boats priced above pocket money. The competition becomes newish boats that qualify for XX money down and monthly payments. They're just easier to sell.
One broker friend says that above $50K we should all offer to take back a note and become the "bank" ourselves. He claims there is little risk for a boat that is going to remain local (don't do it if the boat is moving 500 miles away). Failure to make the payments means you get your boat back and pocket the "rent." A simple repo clause puts you in command, you change the locks or move the boat, and Judge Judy is on your side.
I haven't tried that. I did sell a sailboat long ago to somebody who made a $5000 down payment and then stalled on paying the rest. ("My husband works on an oil platform and in two weeks he'lll be back and I'll pay the rest then." The husband, however, actually had very little interest in his wife's new sailboat, which was news to him). My partner and I went to a lawyer who said, "change the lock, strip the boat of everything that you can remove--sails, cushions, anchor etc." We did. The lawyer wrote a letter saying the down payment was forfeit, and made her sign a doc stating she gave up all rights. So we got 5K for the hassle, and the boat back. Was it worth it?
Nope. When I sold vacuum cleaners door to door we were required to have both hubby and wife present at the close. A lesson I shoulda learned.