Hull Number - United States Military

United States Military

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 USS Enterprise, 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".

The U.S. Navy sometimes ignores the sequence of hull numbering. For example, the Navy built the last Los Angeles-class nuclear submarine as SSN-773. Next the Navy built the three Seawolf class submarines SSN-21 through SSN-23. Then the Navy later resumed the original sequence of hull numbers with the 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 at resulted in only three of these boats being constructed: the U.S.S. Seawolf (SSN-21), the U.S.S. Connecticut (SSN-22), and U.S.S. Jimmy Carter (SSN-23).

Also, whenever warships are constructed in American shipyards for foreign navies, any hull numbers used to identify the ships during their construction are never reused by the U.S. Navy. For example the Perth class guided missile destroyers that were built for the Royal Australian Navy in Michigan were identified as DDG-25, DDG-26, and DDG-27, but these hull numbers were not assigned to and American destroyers after the Australian Navy had changed those to its own identification numbers.

Several other new warships have been constructed in American shipyards for countries like West Germany and Taiwan.

Whenever a naval vessel is modified for use as a different type of ship, it is often assigned a new hull number along with its new classification. Often the actual number remains the same while the hull classification changes. For example, a heavy cruiser (CA) that was converted into a guided missile cruiser became a CG and its number was changed. This happened with the U.S.S. Albany (CA-123), the U.S.S. Chicago (CA-136), and the U.S.S. Columbus (CA-74), which became, respectively, the CG-10, the CG-11, and the CG-12.

Also, during World War II, nine Cleveland-class light cruisers (CL) were coverted as light aircraft carriers (CVL), with different numbers.

During the 1970s, the guided missile frigates that were then redesignated as guided missile cruisers had their designations changed from "DLG" to "CLG", and their numbers were sometimes changed, too. Some other guided-missile frigates were redesignated as guided-missile destroyers (DDG) and given new numbers.

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.