The Law of Ships Article 18

In case the Certificate of Vessel's Nationality (Register) of a ship is missing, broken or any entry therein is altered when it calls at a port other than the port of registry, the master or owner of the ship may apply to the shipping administration authority at the port of calling or port of registry for issuance of a Provisional Certificate of Vessel's Nationality (Register) within 3 months from the date of discovery or occurrence. If the aforesaid event occurs on voyage, the master or owner of the ship may make the above-mentioned application to the shipping administration authority at the port of arrival or port of registry.In case a Provisional Certificate of Vessel's Nationality (Register) is applied for pursuant to the preceding two paragraphs, the ship owner shall apply for replacement or reissuance of the Certificate of Vessel's Nationality (Register) to the shipping administration authority at the port of registry within 3 months from the date of receiving the provisional certificate.