OVERVIEW: The NT 37F is a heavyweight submarine-launched anti-submarine torpedo finalized in 1995 under the NT‑37 series. It features Otto fuel II propulsion, wire guidance, and advanced digital control, enhancing speed, range, and shallow-water performance.

DETAILS: “NT 37” refers to the Northrop Retrofit of the U.S. Navy’s Mk 37 series; “F” denotes the fourth major upgrade. It maintains the Mk 37’s 3.43 m length, 19 in (533 mm) diameter, ~650 kg weight, and 150 kg warhead. The F variant introduces a digital programmable tactical control logic, new signal processor, baffling in the nose section to reduce self-noise, and retains Otto fuel propulsion—all delivering approximately +40% speed and +150% range increases over earlier NT‑37 models. Specifically ordered by Egypt for its Romeo-class submarines, it entered service in the mid-1990s, offering near-doubling of passive and active sonar detection in shallow water and adding anti-surface target run patterns.

TYPE: Heavyweight submarine-launched wire-guided active/passive acoustic homing torpedo

FUNCTION: Launched from 19‑in tubes (with guide rails), it begins on a preset gyro course, then employs wire-guided mid-course updates. The terminal phase uses programmable active/passive sonar homing; it can operate autonomously in “fire-and-forget” mode following wire release.

NOTE:
IOC: Mid-1990s (reported ~1995)
Manufacturer: Honeywell Marine Systems (successor to Northrop), USA
Operators: Egypt (confirmed); other NT‑37 users unclear
Platforms: Romeo-class submarines (Egypt)

SOURCE: Wikipedia “Mark 37 torpedo” (variant list); Homing Instincts article on NT‑37F upgrades; Jane’s Naval Weapons Systems