OVERVIEW: The Spearfish Mod 0 is a heavyweight, wire-guided, submarine-launched torpedo developed by the United Kingdom for anti-submarine and anti-surface warfare. It features a high-speed propulsion system, active/passive acoustic homing, and was designed to defeat both deep-diving submarines and fast surface ships.

DETAILS: "Spearfish" is the official name given to this British heavyweight torpedo developed by Marconi Underwater Systems (now BAE Systems). Spearfish Mod 0 entered service in 1994 as the first production configuration, intended to replace the older Tigerfish torpedoes. It is equipped with an active/passive acoustic seeker, a high-explosive shaped charge warhead, and is wire-guided for mid-course control before transitioning to terminal homing. The propulsion system uses a gas turbine engine fueled by Otto Fuel II, giving it high speed and long endurance.

It was purpose-built to match or exceed the performance of U.S. and Soviet-era torpedoes, giving the Royal Navy credible ASW and ASuW capability.

TYPE: Heavyweight Dual-Purpose Guided Torpedo

FUNCTION: After launch from a 533 mm submarine tube, the Spearfish Mod 0 is wire-guided during the initial phase, allowing updates from the launching submarine. It then uses its active/passive sonar seeker to home in on high-value surface warships or submarines, with high-speed sprint capability to reduce enemy evasion or countermeasure effectiveness.

NOTE:
IOC: 1994 (Spearfish Mod 0)
Manufacturer: United Kingdom (Marconi Underwater Systems / BAE Systems)
Operators: United Kingdom
Platforms: Trafalgar-class submarine, Vanguard-class submarine, Astute-class submarine

SOURCE:
Jane’s Naval Weapon Systems ; UK Ministry of Defence: https://www.gov.uk/government/news/royal-navy-to-get-350m-torpedo-upgrade ; BAE Systems: https://www.baesystems.com/en/product/spearfish-heavyweight-torpedo ; Federation of American Scientists (FAS): https://man.fas.org/dod-101/sys/ship/weaps/index.html ; Wikipedia: https://en.wikipedia.org/wiki/Spearfish_torpedo