since there are no titles for boats in some states when you buy a boat how can you be sure that the previous owner does not owe money to a bank and the boat is owned free and clear?

i dont know if what you said is true. every boat company provides a title for each boat that is manufactured. regardless if it is used in a state that requires a title for registration.

Justin, the mfg's might supply a CoO or a title, but there are many states that do not require a title to register a boat. Some of these will give the title back, some dont. In these states, the registration is the "title".

To the OP's point, I think they might mark liens on the regs... but I dont know for sure.