OVERVIEW: The Type 2066 Bandfish is a British expendable sonar decoy system developed for Royal Navy submarines to counter active and passive homing torpedoes. It is launched from standard 3-inch countermeasure tubes and is designed to mimic or obscure the acoustic signature of the host submarine.

DETAILS: The Type 2066, known by the codename "Bandfish," was developed in the 1980s as part of the Royal Navy’s underwater countermeasure suite. It functions as a mobile acoustic decoy, emitting pre-programmed or responsive acoustic signals to lure away incoming torpedoes. Designed for use by submarines such as the Trafalgar-class and Swiftsure-class, the system can be deployed rapidly in response to a torpedo launch. Once deployed, Bandfish operates either by mimicking the host submarine’s noise signature or by generating confusing noise patterns that interfere with the torpedo’s guidance systems. Its small cylindrical body fits within the 3-inch launcher tubes carried on most Royal Navy submarines.

FONCTION:
Detect incoming torpedo threats using onboard sonar systems.
Launch the Type 2066 Bandfish decoy from a 3-inch countermeasure tube.
Emit acoustic signals to mislead or divert the torpedo from the actual submarine.

SOURCE:
UK Ministry of Defence Underwater Countermeasures Handbook ; Jane’s Underwater Warfare Systems ; Royal Navy Submarine Service Publications ; Federation of American Scientists (https://www.fas.org/man/dod-101/sys/ship/weaps/index.html) ; NATO Naval Armaments Group Technical Reports.