Numerous things bother me about this thread.
1. How does he possess a title if the bank still has loan on it. It would read the bank as the lien holder if he did have it.
2. Most banks have language in their loans that you can not sub let, fractional sale, or otherwise sell half interest in a boat that is actually owned by a bank. This could be a real problem for you so I would want to read the loan language immediately.
3. Bankruptcy usually can end up on the good side of things but if in bankruptcy I would doubt it is on the good side of things. Do you have your own access to the loan details so you can see for yourself if your 11k went to the boat or in his pocket.
4. You need a lawyer, As of next Tuesday, you need a lawyer.
5. Try to get this agreement to have some other type of colateral, such as an agreement that if the boat is lost in BK then he owes you the money back. (This is considering your money did not go towards the loan 100% like it should have)
Now I am assuming not all of your 11K+ went into the loan. My bet is your partner found a way to pay off some bills, and keep his boat. This is an assumption ... but if your money didn't go towards the boat and only towards a tally of your half then your money was stolen.
Last, I wish you the best of luck. And stand firm. You want full disclosure, an signed agreement (Or amendment to your existing agreement) that is the boat is lost to bankruptcy that the partner owes you your money back. and you also want proof of all payments made. Last get a good lawyer not related in any way to your partner.
When I was a child, I used to talk as a child, think as a child, reason as a child; when I became a man, I put aside childish things.
1 Corinthians Chapter 13 - 11