So you have a bill of sale, from who? The registered owner or someone else pulling the same. Many used boats (private sales) are sold multiple times without the registration taking place. So your bill of sale is from someone who isn't on the title either. By this time any bill of sale documents in the chain are long gone, previous owners die etc etc. The last person to legally register it could come back and claim it. story like...had it in long term storage, never checked on it...decided it was time to sell it..went to clean it up...its gone. Spotted it the other day at your house. If you can't prove he sold it 3 or 4 persons back in the chain..your F%@KED.