(c) There shall be indorsed upon the documents of a vessel covered by a preferred mortgage—
(1) The name of the mortgagor and mortgagee;
(2) The time and date the indorsement is made;
(3) The amount and date of maturity of the mortgage; and
(4) Any amount required to be indorsed by the provisions of subdivision (e) or (f) of this subsection.
(d) Such indorsement shall be made (1) by the collector of customs of the port of documentation of the mortgaged vessel, or (2) by the collector of customs of any port in which the vessel is found, if such collector is directed to make the indorsement by the collector of customs of the port of documentation; and no clearance shall be issued to the vessel until such indorsement is made. The collector of customs of the port of documentation shall give such direction by wire or letter at the request of the mortgagee and upon the tender of the cost of communication of such direction. Whenever any new document is issued for the vessel, such indorsement shall be transferred to and indorsed upon the new document by the collector of customs.
(e) A mortgage which includes property other than a vessel shall not be held a preferred mortgage unless the mortgage provides for the separate discharge of such property by the payment of a specified portion of the mortgage indebtedness. If a preferred mortgage so provides for the separate discharge, the amount of the portion of such payment shall be indorsed upon the documents of the vessel.
(f) If a preferred mortgage includes more than one vessel and provides for the separate discharge of each vessel by the payment of a portion of the mortgage indebtedness, the amount of such portion of such payment shall be indorsed upon the documents of the vessel. In case such mortgage does not provide for the separate discharge of a vessel and the vessel is to be sold upon the order of a district court of the United States in a suit in rem in admiralty, the court shall determine the portion of the mortgage indebtedness increased by 20 per centum (1) which, in the opinion of the court, the approximate value of the vessel bears to the approximate value of all the vessels covered by the mortgage, and (2) upon the payment of which the vessel shall be discharged from the mortgage.
Subsection E.
The collector of customs upon the recording of a preferred mortgage shall deliver two certified copies thereof to the mortgagor who shall place, and use due diligence to retain, one copy on board the mortgaged vessel and cause such copy and the documents of the vessel to be exhibited by the master to any person having business with the vessel, which may give rise to a maritime lien upon the vessel or to the sale, conveyance, or mortgage thereof. The master of the vessel shall, upon the request of any such person, exhibit to him the documents of the vessel and the copy of any preferred mortgage of the vessel placed on board thereof.