If you are looking to getting close to what you pay for the boat back out of it. Go with the 04 because it's depreciated itself already. Depending on what you're paying for it you shouldn't get hurt or upside down if you need to liquidate it. The 06 will be a different story unless you hold onto it for 2-3 years because of the amount of interest you're not paying the prinipal down enough.
You should visit a website I use often when making fincancial decisions. It's free and has a bunch of different Java calculators so you can play around with the price and see where the payoff is if you wanted/needed to get rid of it. After you type the financial information into the calculator and hit calculate there's a place at the bottom of the screen to view an amortization schedule. It will launch into a new window and breaks down with each payment the amount of principal and interest you'll be paying. Here's a link to the website http://www.dinkytown.net
I have no affiliation with the website I just like to use it!
Hope this info helps.
(Message edited by knwebs on July 12, 2006)