As the RN begins the transition from crewed minehunters to autonomous systems, the first boat has been deployed to Bahrain in the Persian Gulf. This is a small but significant step and much rests upon the success of this vessel in the operational environment.
The persistent threat of mines
The RN has maintained a forward-deployed mine warfare capability in the Gulf for the last 17 years, typically four MCMVs based in Bahrain for several years with crews rotating in and out from the UK. This force has already been reduced to three, currently comprising HMS Chiddingfold, Middleton and Bangor supported by RFA Cardigan Bay. The Gulf is undoubtedly the sharp end of RN mine warfare activity with the Iranian threat to mine the confined waters traversed by ships that deliver oil and gas across the world an ever-present possibility.
The humble sea mine or IED of the sea poses a complex and evolving challenge to all naval forces. Mine countermeasures is a foundational capability for any serious navy – there is little point in investing £Billions in countering the latest hypersonic anti-ship missiles if your fleet cannot leave port due to the presence of relatively simple mines. Since 1950, the US Navy has suffered 15 warship casualties seriously damaged by mines compared to just 5 damaged by other means of attack. The RN is considered a world leader in MCM and the US Navy, which, perhaps surprisingly has not invested enough in mine countermeasures, sees it as a partner that can help mitigate this weakness.
In a conflict with peer adversaries, as an island nation, the UK is vulnerable to maritime blockade. Mines may be used to impede the passage of merchant ships either in shallow waters and maritime choke points around the globe or even in the ports, harbours and estuaries of the UK. Mines can also exert a direct military effect denying sea areas and preventing naval operations in the littoral.
The threat of mines in the Firth of Clyde and its approaches that could put deterrent submarines and valuable SSNs at risk are given particular priority by the RN. Route surveys (RTSV) of the area produce detailed seabed data which must be updated regularly, making it easier to spot newly laid mines. This is especially important in areas where the seafloor is very uneven with lots of Non-Mine, mine-like Bottom Objects (NOMBO) where it is easier for a potential adversary to lay and disguise mines. Project WILTON has delivered the first uncrewed RTSV capability based at Faslane which will be further enhanced with the arrival of RFA Stirling Castle, dramatically expanding the reach and range of autonomous MCM.
Mines are an attractive and cheap asymmetric weapon, particularly for weaker naval powers, they can be laid relatively easily and the technology continues to develop. Mines can range dramatically in size and complexity. The simple contact mines just below the surface anchored by cables to a sinker on the seabed, little different to those used in the First World War are still a danger to shipping and have been deployed in the Black Sea recently.
Far more sophisticated mines have been developed including devices that can lie dormant on the bottom for months, pre-programmed to activate when signalled or when particular types of ship or submarine noise signatures are detected. Smart, mobile torpedo-like mines with AI capabilities that can reposition or swim to targets and potentially evade MCM forces are also possible. Removing sailors and divers from minefields that are becoming increasingly dangerous is a key objective of the move to autonomous systems.
High-definition sonar will remain the key tool for localising suspicious objects but instead of a small number of hull-mounted systems, will ultimately comprise lighter, more mobile and more numerous sensors. The new autonomous systems will be remotely controlled, at least for the first generation but will still be reliant on the skills of the operator. Processing sonar data with AI may speed up mine recognition and discrimination but the operator must still decide on the course of action and manoeuvre the disposal vehicle laying explosive demolition charges.
The Mine Hunting Capability (MHC) programme is the RN project to that will entirely replace the MCMVs with autonomous systems by 2033. MHC is divided into two main delivery blocks. Block 1 consists of three operational demonstrator systems, one of which is now in the Gulf. The programme and is being brought online in parallel with the retirement of the Sandown class MCMVs between 2021-25. Block 1 is primarily focused on evaluation while Block 2 is the mainstay of the full replacement MCM capability. Block 2 procurement has begun and is funded to deliver up to six mission systems and three Logistics Support Vessels.
RNMB Harrier arrived in Bahrain in early 2023. She is one of five 11-metre boats owned by the RN and built by Atlas Electronic in Dorset. (The other 11m boats are RNMB Hussar, Hazard, Halcyon, Harrier and Hydra. A larger 15-m SEA Class boat, RNMB Hebe is based on the Clyde as part of WILTON). The 11m boats are small enough to be air-transportable by RAF A400M and C-17 aircraft and could also be deployed from the Mission Bay of a Type 26 frigate.
Harrier is not the first boat to deploy to the Gulf, in October 2020 RNMB Halcyon conducted an initial 10-day Sweep Demonstrator hot weather trial run by the RN’s Maritime Autonomous Systems Trial Team (MASTT) and AEUK staff. (Cold weather trials were conducted in Canada during February 2020). RNMB Harrier is the first to be integrated into the operational environment and will operate from RFA Cardigan Bay under the command of the new Mine Threat Exploitation Group (MTXG) established in 2022. Besides testing her from a technical perspective, Harrier will be used to develop the concept of operations and refine command and control systems, integrating with the MCM battlestaff, the UK’s Naval Support Facility in Bahrain and allied nations. Harrier’s first major trial was during the recent 3-week International Maritime Exercise (IMX23 held 26 Feb – 16 Mar) which saw multi-national mine warfare forces deployed in the Gulf and trialling various autonomous systems.
Harrier can operate either manually, be remotely controlled or pre-programmed to conduct a mission autonomously without human intervention. For now, she is only equipped with sensors to detect mines, full mine disposal capability using ROVs is not yet operational. It should be noted that the RN says this is part of a phased approach to bringing in new technology and will be used “to evaluate MHC performance in the Gulf against MCMV capabilities, to inform the transition timeframe”.
Harrier is also capable of delivering the RN’s restored minesweeping capability. Coil Auxiliary Boats (CABs) which simulate the acoustic or magnetic signatures of ships to trigger mines or confirm their presence are towed behind the boat. This is an inherently more risky method than using sonar and then using UUVs to lay demolition charges. However, this is a quicker way to clear a path ahead of a naval force when time is precious and is an ideal task for uncrewed systems.
In April 2022 AEUK were awarded a £32M contract to supply nine SeaCat UUVs as part of the MHC project. SeaCat is a modular submersible with parts that can be quickly swapped out and the RN systems will be equipped with a synthetic aperture sonar (SAS) system and Seebyte Neptune advanced planning and analysis software. AEUK has collaborated with Swedish specialists, Lidan Marine to develop a launch and recovery system (LARS) so that SeaCat can be deployed from either RNMB Harrier and her sister boats or the SEA Class boats.
SAS is very high resolution and can map a site at up to 30 times the resolution of traditional side scan sonar. The ability to deploy a submersible in the water with SAS will complement the Thales-made Synthetic Aperture & Mine Detection Imaging Sonar (SAMDIS). SAMDIS is towed body that will equip the autonomous boats being procured for the MMCM programme that forms the main part of MHC Block 2.
A system of systems approach to MCM will provide the RN with a toolkit of different vehicles, sensors and effectors that can be deployed from the autonomous boats. This offers the flexibility to select the best option to complete the mission, depending on water depth, sonar conditions, visibility, weather and type of mine threat.