Defending the Fleet

Surface Ship Torpedo Defence

Ultra is recognised as a world leader in the design, development and delivery of robust, reactive torpedo countermeasures. In 2001, selected to supply a new torpedo defence system to equip the Royal Navy fleet, Ultra remains the only company to have delivered full sensor to counter-measure capability into service on multiple platforms.

Ultra's Surface Ship Torpedo Defence (SSTD), known as Sonar 2170 for the RN and Sea Sentor for the export market, incorporates both a towed sonar detection capability and towed and expendable countermeasures. SSTD achieved initial operating capability aboard HMS Westminster in October 2004. A total of 16 Sonar 2170 systems are on order. Up to 65 vessels will be equipped with Fit To Receive kits which will allow the rapid installation of SSTD; the pool of systems delivered can then be rotated through these ships as operational deployments require. Designed for use aboard both RN warships (including Frigates, Destroyers and Aircraft Carriers) as well as Royal Fleet Auxiliary (RFA) vessels.

Sonar 2170 is characterised by its simplicity of operation and minimal training requirement. Indeed, computer-based training is being used for both RN sonar operators and RFA point defence operators who will use the system. At the heart of our SSTD solution is a unique Flexible Towed Body (FTB) incorporating a multi-mode countermeasures device. Unlike towed, rigid countermeasure systems, the inherent flexibility of the FTB allows the system to be recovered without the need to disconnect the acoustic body.

The FTB supports a number of modes of operation and while being supplied with default settings, can also be fully programmed by the operator. The torpedo detection element of SSTD, deployed from a single-drum winch, comprises a multi-octave towed torpedo detection array coupled with vibration isolation modules fore and aft, a rope drogue tail for stabilisation, an array tow cable to provide separation between the FTB and acoustic array, and a fibre-optic tow cable. Our complete package also includes an off-board Expendable Acoustic Device (EAD) launched from the ship to lure the torpedo away from its intended target. EADs are pneumatically launched from dedicated eight-round launchers positioned on either beam. The decoys begin transmission within seconds after launch. Fully integrated, these individual components deliver a complete torpedo detection and countermeasures capability. Its database of torpedo information, and associated tactical plans to counter them, allows the SSTD system to graphically present appropriate manoeuvre and countermeasure actions necessary to defeat any threat. Non-relevant threat-based data can be temporarily removed as operational missions require.

The US Navy’s Detection, Classification and Localisation (DCL) is an active torpedo detection system, adding a high-frequency towed source to provide an additional active detection capability, offering the ability to detect all torpedoes fired in a salvo and then pass the target solution to a hard-kill Anti-Torpedo Torpedo (ATT). This active technology, fully complementary to existing S2170 SSTD detection and soft kill functionality, is pushing the boundaries of torpedo defence. Moreover, the active elements of DCL and the ATT targeting solution have been developed such that they can be integrated within the existing SSTD system in order to provide both a hard and soft kill capability. A key enabler for this integration is the open architecture software and open systems hardware designs of our SSTD solutions. First testing of the DCL technology demonstrator took place aboard USS Cleveland in April 2006. A world first was achieved, with DCL accurately detecting and localising a salvo of torpedoes with sufficient time and accuracy for them to be defeated using hard-kill techniques.