"A boat is a hole in the ground into which one throws money."
"Sailing is standing under a cold shower tearing up $100 bills"
With those two old, well-known sayings, it's hard to understand how anyone could look at a boat as an investment. Unless you're living aboard, it's an indulgence.
As for those lonely boats in the harbor, it could be their owners are trying to sell them but nobody is buying.
And to a boat being like a woman, that you have to pay a lot of money to keep her looking shiny and new, she could be saying the same about you.