"SPEARFISH
Type: Submarine-launched dual-purpose heavyweight weapon.
Description: Spearfish is a submarine-launched heavyweight torpedo designed to operate totally autonomously from all Royal Navy submarines and interfacing, with a minimum of modification, to all weapon handling and fire-control systems. It is also designed to meet Royal Navy staff requirements to counter faster, deeper diving, quieter and stronger-hulled submarines, as well as dealing with surface targets.

Spearfish resembles Tigerfish externally but the after body has no fins but a shrouded pump-jet propulsion system. Internally it is subdivided into homing section, warhead, main electronics, fuel and propulsion system. The homing electronics include advanced sonar transducers, which enable it to operate in a primary passive mode. However, when required to operate against a very quiet target or in the final stages of attack, the active mode is used. In this mode, the powerful transmitters give Spearfish a long detection range and enable it to "burn through" enemy countermeasures.

The 300 kg blast and shaped charge PBX-104 warhead is designed to pierce the double hulls of Soviet submarines, which were in service during the 1870's. The advanced homing and computer system enables the torpedo to be guided to the optimum point on the target's hull. Spearfish has an equal capability against surface targets where the acoustic fusing system detonates the warhead under the hull of the target. The blast creates a whipping effect which breaks the ship's back."