After a gap of two decades, the UK Royal Navy (RN) is reintroducing an influence minesweeping capability as part of the broader recapitalisation of its mine countermeasures (MCM) force under the Mine Hunting Capability (MHC) programme.
TKMS Atlas UK – previously known as Atlas Elektronik UK (AEUK) – handed over three new uncrewed surface vessel (USV)-based influence minesweeping systems to Defence Equipment and Support (DE&S) in late June this year. The equipments – part of a suite of payloads and systems being delivered under MHC Block 1 – are now commencing an operational evaluation period with the RN’s Mine and Threat Exploitation Group (MTXG) in advance of transitioning into operational service.
The RN has been without a core minesweeping capability since retiring the Combined Influence Sweep (producing both acoustic and magnetic influences) and Mk 8 Oropesa mechanical wire sweeps from its Hunt class mine countermeasures vessels in late 2005. This decision reflected the fact that the existing equipment was cumbersome to deploy, increasingly obsolete against an evolving threat, optimised for deep water, and required the host platform to sail into the mine danger area ahead of the deployed sweeps.
However, the requirement for a sweep capability has remained. “We talk about probabilities, and the probability of detecting a mine,” said Commander Dan Herridge, commanding officer of the RN’s Mine & Threat Exploitation Group (MTXG). “So if you have certain bottom types – such as high density, high clutter environments with many natural or man-made objects – you will simply not be able to pick out some mine threats regardless of the fidelity and definition of your sonar.
“So influence sweeping remains an important and still relevant technique. What this system does is give the RN a capability to sweep modern, highly sophisticated mine threats.”
What was AEUK previously delivered an MHC Sweep demonstrator – including the 11 meter ARCIMS USV RNMB Hussar – to the RN back in 2018. This pre-production prototype completed a series of operational trials with the Maritime Autonomous Systems Trials Team (now integrated in MXTG Yankee Squadron) in both hot weather and cold climate conditions.
These intensive trials highlighted a number of areas where the demonstrator system needed modification or improvement in respect of robustness and operability. “We learned a lot of lessons based around useability, robustness, handling and transportation,” said Sarah Brown Atlas UK’s MCM Product Lead. “We’ve incorporated those into the final production standard configuration. It has made the system more sailor-proof, but also easier to use.”
She added: “The original intent was that the MHC Sweep would be integrated with, and deployed by, the Hunt class platform. While this is no longer the case, the requirement meant that we had to develop a very low signature solution – for example, we have no permanent magnets in the system. And that means we have a unique capability that could still be operated from a low signature platform if required.”
The MHC Sweep system has been designed for air transportation, hence the decision to specify an 11 meter craft that can fit inside an A400M or C-17 airlifter. Alongside the USV itself, the full equipment set can be housed inside four standard 20 ft ISO containers, including one for a portable command and control (C2) capability.
The main USV payload, installed in the well deck area, is a compact, high-output Power Generation Module (PGM). The PGM is used to generate waveforms for the for the sweep modules towed behind, which can operate in either mine setting mode or target simulation mode.
The most readily identifiable of these modules are the Coil Auxiliary Boats (CABs), up to three of which can be towed behind the ARCIMS platform. Each CAB carries closed loop coils for generating magnetic fields. These are independently controlled from the PGM, which enables the user to create different signatures by independently controlling the coils with different fields. Coils can be set to different angles, directions, and polarisations, while changing the spacing between CABs allows different distributions of signature to be replicated. To generate electrical fields, a pair of underwater electrodes can be fitted beneath the CABs.
One technical challenge was the need to identify a CAB boat design and material solution able to withstand the shock of an underwater explosion while at the same time enabling ‘foldaway’ packaging. To achieve this, Atlas UK has employed an inflatable design fabricated from a drop stitch material very similar to that used for paddle boards.
An alternative open loop magnetic electrode sweep is also available. While the CAB is a more sophisticated and higher fidelity source optimised for creating or replicating different types of ship signature, the electrodes are good for creating large magnetic fields for high clearance rates.
Various acoustic influences are available. These comprise a hydro-powered acoustic source (a mechanical device which generates high levels of broadband noise); a programmable acoustic source (suspended below the surfaced at the tail end of the sweep); and an echo repeater.
A float is fitted at the end of the sweep to serve two functions. First, it supports the acoustic systems which being towed beneath the water. Second, a sweep monitoring system is fitted on the back of the float to enable the operator to track the back of the sweep, and also to provide a function to detect mine actuations.
The RN currently has five ARCIMS craft in service, comprising RNMB Hazard, RNMB Halcyon, RNMB Hussar, RNMB Hydra and RNMB Harrier. While Hazard is currently configured as a crewed workboat, the remaining four craft are all enabled for autonomous/uncrewed operations: the ‘sense and avoid’ sub-system fitted on board comprises sensors and processing components (radar, cameras and AIS) to allow the vehicle to detect static and moving obstacles and avoid collision.
USV control is exercised from the portable C2 container using Atlas UK’s own UXV Console autonomy and control software. The operator sits at a twin-screen station: the left-hand screen shows the tactical picture and mission plans; the right-hand screen shows the sensor picture (radar or cameras) from the ARCIMS vehicle.
High data rate and low data rate communications are enabled via line-of-sight radios. The former provides bandwidth for the full tactical picture, situational awareness and control; the latter is more limited in bandwidth but enables ‘get home’ control.
The MHC Block 2 programme projects the acquisition of a further three MHC Sweep systems, for which DE&S and Atlas UK have begun initial commercial discussions. As part of MHC Block 2, the RN also intends that currently discrete C2 systems for the MHC Sweep, the Maritime Mine Countermeasures mine hunting system (Thales) and autonomous underwater vehicles (SeeByte) will be amalgamated into a single C2 architecture hosted in a common Remote Control Centre.
