OVERVIEW: The Sea Siren (Type 182) is a towed acoustic torpedo decoy system designed to protect surface ships from acoustic-homing torpedoes. It functions as a passive soft-kill countermeasure by emitting deceptive acoustic signatures from behind the ship.

DETAILS: Developed in the United Kingdom by Graseby Marine in the early 1970s, the Type 182 decoy was engineered for surface warships and operates by creating an alternate acoustic target for incoming torpedoes. Unpowered torpedo-shaped decoy, towed astern by cable. It emits or reflects acoustic noise that mimics the host ship’s profile or simulates the signal of an active homing torpedo seeker. The decoy is deployed approximately 1 nautical mile behind the vessel to ensure separation and maximum effect against torpedo tracking systems.

FUNCTION: Once deployed, the decoy trails the ship on a cable and radiates acoustic energy or reflections designed to seduce torpedoes away from the main hull. Its effectiveness relies on acoustic mimicry and distance from the ship to act as a more attractive target for both active and passive homing torpedoes.

NOTE:
IOC: 1970s (Sea Siren / Type 182)
Operators: United Kingdom; Chile; Malaysia (Lekiu-class)

SOURCE:
Military Periscope: https://www.militaryperiscope.com/weapons/sensorselectronics/electronic-support-measureselectronic-warfare/type-182/overview/ ; Haze Gray & Underway — UK Frigates Equipment: http://www.hazegray.org/navhist/rn/frigates/ ; UK Royal Navy Decoy Systems Handbook ; Naval Institute Proceedings – British Surface Ship Countermeasures