OVERVIEW:  The Mk 14 is a heavyweight United States Navy submarine-launched torpedo designed for anti-ship warfare. It is steam-driven, gyroscope-guided, and served as the main offensive torpedo aboard US submarines during World War II.

DETAILS:  The “Mark” designation denotes its position in the US Navy torpedo series; Mk 14 reflects a 21‑inch diameter, steam-powered design developed beginning in 1931. It measures approximately 6.25 m in length, weighs about 1 488 kg, and carries a 292 kg Torpex warhead with both contact and magnetic influence exploders. Powered by a wet-heater steam turbine using alcohol‑air fuel, it features selectable speed-range settings: high speed (46 kn for 4 500 yd) or low speed (31 kn for 9 000 yd). Despite initial deployment in 1938, it suffered severe reliability issues (including running too deep, faulty exploder mechanisms, and gyro malfunctions) that persisted until reforms in 1943–44; post‑refinement, it became a critical asset in sinking Japanese shipping. It remained in USN service into the 1970s and influenced later torpedo designs.

TYPE: Heavyweight submarine-launched anti-ship torpedo

FUNCTION:  The Mk 14 is fired from 533 mm submarine tubes, using gyroscopic stabilization to maintain course and selectable speed settings. Upon detecting a target, it detonates via contact or magnetic pistol under or upon impact to maximize hull damage.

NOTE:
IOC: 1931 (Mk14 Mod 0), 1943 (Mk14 Mod 3)
Manufacturer: US Naval Torpedo Station Newport and satellite production yards (Alexandria, Keyport, Forest Park)
Operators: United States
Platforms: US fleet submarines of WWII (e.g., Gato, Balao, Tench classes)
Conflict used in: World War II (Pacific theater)

SOURCE: Naval History and Heritage Command; Pacific War Online Encyclopedia Mark 14 Torpedo; Warfare History Network “The Defective Mark 14 Torpedo”; designation‑systems.net Mark Series Torpedoes