Get the USCG abstract of title. That will list the owner and lien history
and tell you if all the liens are clear. That is all I would do.

But be aware that any shipyard has an implied lien for unpaid work that runs
with the vessel and not the owner who incurred the debt. It is rather rare
for this situation to be claimed, but there isn't much you can do about it
other than buy title insurance. Title insurance is available but expensive.

So, go with the USCG abstract and you will be 99.99% clear.

David