OVERVIEW:  The Mk 37 Mod 2 is a heavyweight U.S. Navy submarine-launched torpedo introduced in 1967 as an upgrade to Mod 1, featuring wire guidance and improved sonar capabilities for anti-submarine warfare.

DETAILS:  “Mark 37” identifies the U.S. Navy’s post-WWII acoustic homing torpedo series; Mod 2 denotes the refurbishment of Mod 1 units starting in 1967. It measures approximately 4.09 m in length, 533 mm diameter, weighs about 767 kg, and carries a 150 kg HBX‑3 warhead. Mod 2 introduced piezoelectric transducers replacing earlier magnetostrictive types, increasing acoustic acquisition range from ~640 m to ~910 m; electronics were modernized with solid-state components. Propulsion remains electric via Mark 46 silver‑zinc batteries, offering two speed/range settings: ~17 kn for ~21 km or ~26 kn for ~10 km. Guidance combines initial gyroscopic straight run, mid-course wire guidance, and terminal active/passive sonar homing.

TYPE: Heavyweight submarine-launched wire-guided acoustic homing torpedo

FUNCTION:  Fired from 21‑inch submarine tubes, the Mk 37 Mod 2 uses wire control to receive course updates during mid-course, then releases the wire and activates its acoustic seeker in the terminal phase to home in on a submarine target and detonate upon impact.

NOTE:
IOC: 1967 (Mod 2 conversion completion)
Manufacturer: Naval Ordnance Station, Forest Park, USA
Operators: United States; exported under Military Assistance Program (e.g., Netherlands, Israel)
Platforms: U.S. Navy submarines with 21‑inch tubes—fleet and nuclear attack types
Conflict used in: No confirmed combat deployment by U.S. Navy

SOURCE: Mark 37 torpedo (Wikipedia); U.S. NAVY TORPEDOES – NSL Archive; USA Torpedoes since WWII – NavWeaps