The UK Royal Navy is proceeding full speed ahead towards completely abandoning the use of crewed specialist mine hunting vessels, as sea trials of uncrewed mine countermeasures (MCM) motor boats continue apace in British and Middle Eastern waters. Also, the RN has acquired the 2013-vintage, Norwegian-built former offshore support vessel (OSV) Island Crown from commercial sources.
Renamed Stirling Castle, this new asset has been converted into an MCM mothership and has joined the fleet of the RN's paramilitary support force, the Royal Feet Auxiliary (RFA). It flies the RFA blue ensign and will be operated on a two-crew basis, working two months on and two months off The crew will usually be made up of RFA sailors and about 40 specialist RN personnel. The UK Ministry of Defence considers this hybrid arrangement to be cost-effective.
Another advantage accrued from being under the RFA ensign is greater flexibility in deployment, as the diplomatic clearance procedures for "civilian" RFA vessels to enter foreign ports are less onerous than those required for RN warships.
The 3,000-tonne, 97-metre Stirling Castle features diesel-electric propulsion, two stern-mounted azimuthing thrusters, two bow thrusters, and a retractable azimuthing thruster at the bow. This combination delivers an ability to remain static while directing MCM operations from an offshore position, as well as enabling a high level of manoeuvrability. Such a capability is deemed to be highly useful in view of the small ports and restricted waterways within which the ship is likely to have to operate from time to time. The RFA currently has few officers qualified in dynamic positioning (DP) and is therefore sending a tranche of personnel on DP training courses.
A large crane mounted aft should prove to be valuable in handling uncrewed and even crewed boats. A dedicated boat launch and recovery system will probably be fitted in due course.
There is a large aluminium flight deck, but it is not certified to accept heavy naval helicopters and so is unlikely to be used, except in emergency situations. The vessel remains unarmed for the time being, but there are reportedly plans to fit mountings for a number of heavy machine guns.
Featuring a large, sheltered working deck as well as copious living, administration, and maintenance spaces, OSVs are ideal for uncrewed MCM boat support tasks. The RN intends to purchase up to three more such ships.
Atlas Elektronik UK has so far delivered six 40-knot, uncrewed 11-metre MCM catamarans to the RN for embarkation on mother ships. The 11-metre craft have been named Harrier, Hussar, Hazard, Halcyon, and Hydra, while a 15-metre example has been named Hebe. At least six additional craft are due to be acquired. The vessels are classified as Royal Navy Motor Boats, and their names carry the prefix "RNMB". The boats' hulls are manufactured by Norco in Dorset, England.
The craft can operate autonomously or be controlled remotely from a mothership, a shore station, or another MCM boat. They feature advanced autonomous navigation equipment as well as anti-collision systems to facilitate the conduct of operations in accordance with the International Rules for the Prevention of Collision at Sea.
Equipped to target and dispose of both magnetic and acoustic influence mines, they can operate a towed sonar array as well tow auxiliary boats that are designed to replicate warships' underwater "signatures" so as to deliberately detonate mines.
A very recent addition to the RNMB inventory is the Anglo-French Apollo MCM monohull boat. Constructed by L3Harris near Portsmouth under a Thales UK contract, the craft recently passed a demanding series of operational trials. Apollo is to undergo evaluation by the RN, but future production plans are currently unclear.
The plan is for a mothership and a number of uncrewed MCM craft to be based at Faslane in Scotland, where they will be available to rapidly counter any attempt to use mines to hamper the egress of the submarines of the UK's undersea nuclear deterrence force. Another mothership and its embarked MCM boats will be deployed long-term in Middle Eastern waters.
The RN is placing great emphasis upon the advantages of a wholly uncrewed MCM capability, namely, endurance, precision, and the reduction of risk to its sailors. Not all analysts are convinced, however, and they point to the potential vulnerability of the boats and their motherships in even a very limited war scenario, a factor that would require the deployment of front-line assets to provide force protection.
There are also concerns over the significant resultant reduction in the RN's already sparse surface ship order of battle.
In reality, it is likely that finance is a major driver of this policy. Not only are small uncrewed assets much cheaper to build and operate than crewed warships, but the sale of the existing crewed minehunter inventory is raising some useful funds for the hugely indebted UK economy.
