Hull number

In 1972, The United States Coast Guard was asked to create a standardized format for HINs to allow for better tracking of accidents and history of boats.

For example, there have been at least eight vessels named USS Enterprise, but CV-6 uniquely identifies the World War II aircraft carrier from all others.

Then the Navy later resumed the original sequence of hull numbers with USS Virginia (SSN-774) for its next class of nuclear attack submarines.

This change in numbering was done because the Seawolf class was to have a radical new and large design for the continuation of the Cold War into the 21st century, but cost overruns combined with the end of the Cold War, and the resulting reduction of the Navy's construction budget resulted in only three of these boats being constructed: Seawolf (SSN-21), Connecticut (SSN-22), and Jimmy Carter (SSN-23).

Guided-missile frigates were constructed in Portugal under military-assistance aid packages were given the hull numbers DEG 7 through 11.

Hull numbers have been used to identify armored tanks for the U.S. Army and the U.S. Marine Corps, and other military services, also.

An example CID/HIN might appear as "GB-ABC00042-A8-99", where "GB" is the ISO 3166-1 country code, "ABC" would be the Acme Boat Company's Manufacturer Identity Code (MIC); "00042" would be the forty-second hull constructed by the organisation; "A8" would be January 1998 for the date keel was laid to the nearest month and "99" denoted as the year 1999 as the particular model year.

[5] Amateur boat builders in the United Kingdom may apply for one-off HIN from the Royal Yacht Association who will issue one number from their "GB-RYAxxxxx" range.