Banks like to use smoke and mirrors to hide profiteering.
They probably want the $600 to use THEIR highly paid agent, because they trust their own agent and they don't trust you or the USCG to do a proper title/lien search. What they really want, is proof that you are getting clear title with no liens.
But it is their money
so they will do it their way or not do it.
If the vessel was professionally built after 1972(?) there will be a "HIN" hull
identification number in at least one place on the boat. You can email
or CALL the USCG Vessel Documentation Center and they are quite happy to explain what and where to look for, and what the actual laws are.
If you belong to a credit union, you may be able to get better terms. If the boat is +30 years old...fewer lenders are willing to take it on. And if you get some other type of loan (as opposed to a mortgage secured by title to the boat) then you don't get the chance to deduct mortgage-related costs on your tax filings. Tradeoffs.
But there are lots of banks and lenders, if one isn't being reasonable...know your facts, don't be afraid to ask for better terms or behavior.