The easiest way to determine whether or not a documented US vessel has a mortgage on it is to apply for an Abstract of Title.
That Abstract will include whether or not there are any mortgages/liens against the vessel. Additionally, it will tell you the status of those mortgages/liens, whether or not they have been satisfied, and so forth. Plus, the Abstract will include the vessel owner as well as its chain of ownership among other information.
At our site, if you have a vessel’s Official Number or Hull Identification Number (HIN), you can conduct a vessel documentation search. This will give you a vessel’s dimensions, information about its flag, name, vessel documentation status, and more. It will not include any mortgages/liens against the vessel nor will it include any information about the vessel owner(s).