The UK Ministry of Defence (MoD) is moving forward with plans to buy three Offshore Support Vessels (OSVs) as part of the Royal Navy’s (RN’s) Mine Hunting Capability (MHC) Block 2 programme.
Speaking at the Navy Leaders CNE 2025 event on 20 May, Bill Biggs, MHC System of Systems architect in the MoD’s Defence Equipment and Support (DE&S) organisation, said the MoD had shaped a requirement for a non-complex commercial derivative design to be delivered from the early 2030s. He added that a delivery team had been stood up, with current plans looking at a contract award in mid-2027.
The MHC programme is an overarching recapitalisation intended to transition the RN’s conventional ship-based MCM force to a next-generation capability based on maritime offboard ‘system of systems’ packages able to execute MCM operations both in home waters and overseas. The aim is to exploit new technology – in areas such as autonomy, sensors and advanced data processing – to make the detection and disposal of sea mines safer, more efficient, and more effective.
The MHC Block 1 programme is already delivering initial ‘toolbox’ components including unmanned surface vessel (USV)-based mine hunting suites produced by Thales under the French/UK Maritime Mine Counter Measures programme; MHC Sweep systems developed by Atlas Elektronik UK (AEUK); Medium Autonomous Underwater Vehicle systems also delivered by AEUK (using the SeaCat vehicle and Vision SAS Mk 2 synthetic aperture sonar); and a suite of command and control (C2) and collaborative autonomy software solutions provided by SeeByte. In addition, the MoD in early 2023 purchased the offshore vessel MV Island Crown – renamed RFA Stirling Castle – from the commercial market to serve as a UK host platform for autonomous MCM payloads procured through MHC Block 1 and the precursor Project Wilton.
MHC Block 2, planned to deliver incrementally between 2026 and 2032, is intended to establish a digital ‘backbone’ for data exploitation and interoperability, while also growing mass in mission systems. This includes additional mine hunting, neutralisation and sweep systems, additional USVs, and a new medium unmanned underwater vehicle (UUV).
Three OSVs – which will function as mother ships for MHC elements – are also planned under MHC Block 2. DE&S earlier this month released a voluntary transparency notice declaring a budget of £330 million for the programme, and advising its intention to commence a tender activity in November 2026.
“[Our programme] includes the requirement for three minimally modified, commercial designed Offshore Support Vessels able to host a full mission system,” Biggs told the CNE 2025 audience. “In indicative terms, that’s in the order of three USVs, three medium class UUVs, and C2 payloads.
“We have a delivery team established, which is an important step [and] we’ve done a lot of work in terms of understanding our core requirements and concepts. That’s helped us shape the requirement.”
The Naval Design Partnering team – which provides technical resource to the MoD for pre-concept and concept design activity – has supported OSV requirements analysis and concept development. Biggs added that the MHC team had also completed “a couple of design excursions around the representative commercial design…that’s allowed us to focus on a number of things around our requirement.”
DE&S in July 2024 announced that it was awarding Kongsberg Defence and Aerospace an eight-month MHC OSV Design Excursion contract funding the company to examine if its Vanguard design could be utilised to demonstrate the suitability of an indicative commercial design as the basis for the OSV requirement. This contract completed at the end March 2025.
According to Biggs, key considerations for the OSV include the complexities around mission system integration, launch and recovery, integration with C2, accommodation, and to what extent the design is ‘minimally modified’ in respect of certification and survivability. “We anticipate further market engagement later this year,” he added. “This is a programme that is now very much moving.”
An RN source told Naval News that the objective was for the OSV to be a less complex vessel, thereby allowing greater investment to be made in the MHC mission systems and associated payloads. There was also a desire to ensure that future MHC mission system options should not be constrained to a certain size/length of USV, and would offer flexibility to embark other vehicles/payloads outside of the MCM role. Both open aft working decks and hangar-type arrangements remain under review. As regards the launch and recovery of USVs, the MHC programme is at this stage leaning towards a stern ramp system: to gain more experience in this area, the MoD is actively looking at putting a ramp on the stern of RFA Stirling Castle. It is anticipated that a general purpose crane will be fitted on the OSV to allow for the embarkation/disembarkation of other payloads, and ‘over the side’ launch and recovery of USVs and other craft in more benign sea conditions.
