On 7 October, the Maritime Equipment and Warfare team at DE&S placed an order with Systems Engineering & Assessment Ltd (SEA) which includes a technical refresh for the NATO Sea Gnat decoy launcher system, (officially named Outfit DLH in RN service). There have been hopes for some time that the RN will obtain a trainable launcher but for now, SEA says the contract involves “upgrade the ships’ countermeasure capability with a new fixed barrel system”.
The contract also covers control system upgrades to resolve obsolescence issues on the Type 23 frigates’ magazine torpedo launch systems (MTLS). 8 of the frigates will receive the update which includes open architecture to improve integration with the combat system and ease future modifications. Despite the continued investment in existing systems, there has been no order for an MTLS to be fitted to the RN’s Type 26 anti-submarine frigates. Space is allocated in the design and the Australian and Canadian derivatives will carry the weapon.
The £34M contract is the largest the RN has ever awarded to SEA and in addition to the decoy system and MTLS modifications, also included are changes to the air-weapons handling equipment. These are likely to be modifications to handle the new Sea Venom and Martlet missiles safely.
Sea Gnat consists of sets of 6-barrelled 130mm mortars with 1 or 2 pairs mounted on the upper deck on each side of the ship. (Typically called Mk 36 Super Rapid Blooming Offboard Chaff (SRBOC) in USN service). The mortars are hand-loaded from ready-use lockers and can launch 3 types of decoy rounds. RF seduction or ‘chaff’ rounds contain hundreds of strips of foil to create a radar reflective cloud intended to lure radar-guided missiles away from the ship. Infra-red rounds (main image above) use flares to attract missiles that rely on heat signatures for guidance. Active rounds descend slowly by parachute and transmit radar signals either in deception mode to confuse the missile seeker or in jamming mode to blind the radar.
The Outfit DLH chaff decoys made by Chemring include the Mk214 Mod 1 which is a 23Kg round. The Mk216 Mk1 Type 1 is a slightly more sophisticated 27kg round with a barometric height sensor which detonates the chaff cloud at the correct attitude whatever the ship’s movement. The Mk 245 A2 is an IR seduction round that includes five sequential, airburst submunitions which ignite flares at 7-second intervals.
The Mk251 Siren Off-board Active Decoy (OBAD) round was developed by Marconi (now Selex ES) and has been in service as part of the Outfit DLH suite since 2003. A low-G rocket fires the round upward and out to around 500m away from the ship, it then descends on a parachute, utilising a parasail wing that allows the decoy to manoeuvre slowly. The onboard computer manages the multimode I/J-band jammer.
Outfit DLH consists of either twin or quadruple six-barrel launchers bolted to the upper deck which cannot be trained to launch a decoy in the optimal direction to counter incoming threats. The ship must use precious time to manoeuvre onto the best heading in the given wind conditions before launching the countermeasures. As anti-ship missiles have increased in speed there is decreasing time to react. The bolt-on Sea Gnat is cheap, reliable and simple solution but more sophisticated trainable launchers have been in development for many years.
As far back as 2010 Chemring demonstrated their Centurion launcher prototype which contains 12 barrels on a rotary mounting enclosed in a cupola with a low radar cross-section. This would increase reaction time and can be pre-loaded with a variety of rounds. Positional accuracy is further enhanced by stabilising the mount to compensate for the ship’s motion.
Centurion also has the potential to counter threats beyond missiles and could be loaded with anti-torpedo countermeasures / small depth charges. In 2013 Chemring teamed up with Raytheon to experiment using the Centurion to launch a Javelin anti-tank weapon with the intention to adapt it for maritime use to counter FIAC or small boat swarming attacks. In 2019 the RN conducted an experimental test-firing of Marlet missiles from panniers on its 30mm gun mountings but it was not deemed a success, mainly due to efflux management issues. It is possible that Centurion or a similar purpose-built decoy launcher could also be adapted to provide a better platform for the delivery of lightweight defensive missiles such as Martlet or a maritime NLAW variant.
Centurion or an equivalent would appear to be a significant and low-cost enhancement to RN surface ship defensive capabilities and it is hard to understand procurement has been delayed for so long. However, in January 2022, DE&S published a Prior Information Notice (PIN) stating “a requirement for a Trainable Launcher capable of deploying future and legacy rounds”. This forms part of the wider Electronic Warfare Countermeasures (EWCM) project, which includes the Maritime Electronic Warfare Programme (MEWP) project. This will eventually provide a broad range of enhancements to RN EW and soft kill countermeasures capabilities.
Defeating the counter-countermeasures
Adversary anti-ship missile systems are not only gaining speed but are increasingly able to accurately discriminate between the intended targets and decoys. This requires countermeasures to evolve with similar levels of sophistication. Not only are faster reactions needed but the decoys must be positioned with more accuracy. A new generation of missiles designed for use in cluttered littoral environments have sophisticated pattern recognition algorithms and can visually identify individual targets so will not be easily seduced by the radar return of a chaff cloud or heat from a flare. This would imply that ship-mounted EW systems or active RF decoys are likely to be the most effective form of soft kill defence against missiles using active I, J or Ka-band radar for terminal guidance. Passive IR-guided missiles such as the Kongsberg/Raytheon Naval Strike Missile are especially hard to defeat using soft-kill countermeasures.
The Anglo-French Acccolade technology demonstrator was run by Thales between 2011-16. The initial concept of a manoeuvring expendable airborne RF decoy carrier vehicle was not fully developed but the programme was used to de-risk concepts including a miniaturised RF transmitter derived from Thales’ Scorpion advanced shipborne jammer. Like the Centurion system, Accolade was test-fired on Sailsbury Plain but has not made it into operational service. Thales says the development of OBAD rounds continues today based on work done with Accolade but focused on a different concept of operations and utilising the latest electronics. MEWP includes plans to replace the obsolete Mk 251 Siren round but it is unclear when this will be in service.
The more obvious hard-kill close-in weapon systems catch the eye but another important layer of soft-kill defences are often overlooked or underestimated when assessing warship capabilities. The RN is generally acknowledged to have good defensive electronic warfare systems and passive countermeasures and through MWEP is working to resolve obsolescence issues and keep pace with emerging threats.