Spearfish Mod 1 heavyweight torpedo completes SATs onboard Vanguard-class SSBN

The Spearfish Mod 1 heavyweight torpedo has completed sea acceptance testing onboard a Vanguard-class SSBN. (Royal Navy)

The latest version of the Spearfish submarine-launched heavyweight torpedo has completed sea acceptance testing (SAT) onboard one of the UK Royal Navy's (RN's) Vanguard-class nuclear-powered ballistic missile submarines (SSBNs).

Announcing the milestone on 2 August, the RN said it marked the first time the upgraded torpedo, known as Spearfish Mod 1, had been tested onboard an SSBN and means that both the Astute-class nuclear-powered attack submarines (SSNs) and Vanguard-class SSBNs have now completed SATs for the improved variant.

The latest trials were conducted over three days off the coast of Scotland and involved the weapon engaging surface and submerged targets, enabling the boat's crew to operate the new weapon, test the ability to fire it from the SSBN's combat system, and ensure command-and-control over the weapon, the RN said.

Spearfish is a submarine-launched, active-passive, wire-guided, anti-submarine, and anti-ship heavyweight torpedo developed by BAE Systems to equip all RN submarines.

Spearfish Mod 0 has been operational for almost 30 years, having entered service with the RN since 1994. The Mod 1 version was developed by BAE Systems Maritime Services under a GBP270 million (USD344 million) upgrade contract awarded in 2014, and is intended to improve safety, reduce through-life costs, and remove obsolescence.

Spearfish Mod 1 retains the existing hull and Sundstrand 21TP04 thermal propulsion from Spearfish Mod 0 while introducing a new insensitive munition (IM)-compliant warhead; a single Otto II fuel cell (replacing the current dual-fuel Otto/HAP system) to provide safer, more reliable propulsion; a fully digital weapon architecture (both hardware and software); and a new high-bandwidth fibre-optic datalink to improve its accuracy and lethality.