If your credit unit has visa balance transfers, you can use that.
Mine offers like 2.9% for over a year. you basically pay cash for it, then after a year it goes to 9.9%
You get the boat title day 1, and within a year either pay it off or roll to another card.
this method isn't for everyone... you have to be creative and disciplined to make it work to your advantage...
or, if you own your car, most credit unions can refinance that. hand over your car title, get cash, pay for boat. car loans are much cheaper/easier.
for reference, a 5 year should be like 2.5% or maybe 3% on the car. with no fees...
Not to mention HELOC options. However thanks to commander bananna's it's no longer tax deductible.