solman, don't take this the wrong way, understand that I am playing devil's advocate here, so don't be offended and please play along...
If I am selling a boat and someone approaches me about offering to hold the note and be essentially the Bank of Me, four questions come to mind:
1. Why couldn't this guy get a loan from his own bank?
2. Why should i give him a loan when his own bank doesn't think he is a good risk?
3. What collateral has this guy got that will give me some security?
4. What's in it for me?
Unless you can successfully answer all of those questions and sell yourself as a viable solution to the seller's still-got-a-boat-for-sale problem, i fear you are still just walking the docks and dreaming, kid.