I would offer this: Let one of you buy the boat. The other can put an amount into an account to cover more of the boat bills. This way one of you would spend more money, the other would eat the depreciation.
If things go south, one of you can walk away and the other keep the boat. Most importantly you won't have the stress of being "locked into a relationship".
I've seen more than a few "happy" couples blow it by complicating things and it seems that you might be a couple who thrives on simplicity. JMHO.
Last edited by RobGallagher; 07-02-2011 at 10:30 PM.