46 U.S.C. § 31324

(a)

On request, the owner, master, or individual in charge of a vessel covered by a preferred mortgage shall permit a person to examine the mortgage if the person has business with the vessel that may give rise to a maritime lien or the sale, conveyance, mortgage, or assignment of a mortgage of the vessel.

(b)

A mortgagor of a preferred mortgage covering a self-propelled vessel shall use diligence in keeping a certified copy of the mortgage on the vessel.