I bought a boat,from a third party can i get in trouble still no title or owner sig?

from a guy frank selling a boat on craiglist,i went to ook at the boat and frank told me a story about how the owner of the boat is in the hospital in bad shape so it might be hard to et the paper work ..he did call the owner while i was there to agree on price 2500 .i had him wright me ou a quick bill of sale on behalf of the owner ...its be hard to get the paper work since ...can i get in trouble for not talkin to the owner of the boat and buying therw a 3rd party