Unsecured line of Credit
Before the financial crisis (ie I don't know if they do these anymore) I was given an unsecured line of credit from Bank of America for 20k at 8% open for 10 years, although I never ended up using it and later closed it.
In my mind that would be a great way to go if you don't use a home equity loan. "In theory" most older boats will hold their value as long as they are properly maintained. As you pay the loan down you can still write yourself a check from the line for replacing things that wear out like 3k here and 3k there for sails, engine rebuilds, bottom jobs, dinghies, and other things that you'll eventually break.
I ended up paying cash for a smaller one and then saved for a while and bought the one I wanted before. Everyone's situation is different, my job wasn't secure enough for me to feel comfortable financing.
I think the credit line is a great way to go.