Hull number

Hull number is a serial identification number given to a boat or ship. For the military, a lower number implies an older vessel. For civilian use, the HIN is used to trace the boat's history. The precise usage varies by country and type.

For civilian craft manufactured in the United States, the hull number is given to the vessel when it is built and forms part of the hull identification number, which uniquely identifies the vessel and must be permanently affixed to the hull in at least two places. A Hull Identification Number (HIN) is a unique set of 12 characters, similar to the Vehicle Identification Number which is found on automobiles. In 1972, The U.S. Coast Guard was asked to create a standardized format for HINs to allow for better tracking of accidents and history of boats. This HIN format is as follows: The first three characters consist of the Manufacturers Index Code (MIC) and should only be letters. The following five characters are the unique serial number assigned by the Manufacturer, and can be a series of letters and/or numbers with the exception of the letters O, I, and Q (they can be easily mistaken). The last four characters determine the model and certification year of the boat. The HIN may be found on the aft of the vessel in the uppermost right corner. Also, the HIN may be stated on the title, registration, and insurance documents.

The United States Navy, United States Coast Guard, and United States National Oceanic and Atmospheric Administration employ hull numbers in conjunction with a hull classification symbol to uniquely identify vessels and to aid identification. A particular combination of hull classification and hull number is never reused and therefore provides a means to uniquely identify a particular ship. For example, there have been at least eight vessels named , but CV-6 uniquely identifies the World War II aircraft carrier from all others. For convenience, the combined designation, which is painted on the sides of the hulls, is frequently called the "hull number".

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