X-1 (submarine)

Entering service in 1955, the X-1 was an experimental U.S. Navy midget submarine built principally to help understand the threat of very small submarines against harbors.

Midget submarines were used extensively, if not effectively, by the Imperial Japanese Navy. They were also used by the Royal Navy for special missions including an underwater attack on the battleship DKM Tirpitz. Italy and Britain also used even smaller underwater swimmer delivery vehicles, to be distinguished from Japanese kaiten manned torpedoes, a suicide weapon.

The X-1, 49 feet long and with a submerged displacement of 36 tons, first used a hydrogen peroxide propulsion system. Hydrogen peroxide, while dangerously reactive, demonstrated significant promise for air-independent propulsion with the German Type XXIII U-bots. The X-1, however, suffered an explosion in the propulsion system on 20 May 1957, and was converted to diesel-electric drive, and then taken out of service until 1960.

"Towed to Annapolis in December 1960, X-l was reactivated and attached to Submarine Squadron 6 and based at the Small Craft Facility of the Severn River Command for experimental duties in Chesapeake Bay. In tests conducted under the auspices of the Naval Research Laboratory, X-l performed for scientists who observed her operations from a platform suspended beneath the Bay Bridge, to learn more about the properties and actions of sea water.

"Remaining in an active, in service, status through January 1973, X-l was again taken out of service on 16 February 1973 and, on 26 April, was transferred to the Naval Ship Research and Development Center, Annapolis. On 9 July 1974, the submersible was slated for use as a historical exhibit; and she was subsequently placed on display on the grounds of the Naval Station complex, North Severn, near Annapolis."