As far as paper fleets go, the UK government’s plan to build up to 12 of the next generation SSN AUKUS (SSN-A) nuclear-powered attack submarines for the Royal Navy is right at the apogee of defence ambition.
In this scenario, an emboldened Royal Navy, operating at some point in the 2040s, will begin to replace its existing seven-strong Astute-class SSNs with new, let’s call them the ‘Fantasy class’, SSN-A boats, derived from the AUKUS platforms being jointly developed with Australia.
A drumbeat of one Fantasy-class SSN would be completed every 18 months, adding the equivalent of an entire Astute class fleet in the time is took to build a single one of its forebears.
Given this target, it can be extrapolated the UK government envisioned it could take 18 years to build the entire new 12-strong attack submarine fleet, less time than it takes the first two Astute boats to be built and commissioned into service.
Broadly speaking, this pace would comfortably allow for the inclusion of additional SSN-A submarines for Australia if needed and provide a degree of leeway for any delays while still maintaining a rough service life of each SSN of around 25-30 years.
Sitting in opposition, the ousted Conservative Party, whose defence legacy the current Labour government has somewhat inherited, sought to pour cold water on the UK plans to increase the number of SSN in the fleet by five boats.
James Cartlidge, Shadow Defence Secretary, said at the time of the government announcement that there was no plan in how to pay for the ambitions of the Strategic Defence Review (SDR).
“The biggest headline announcement of the SDR was 12 new attack submarines – but the Secretary of State on the media round was completely flummoxed when asked how many would actually be built, and how much they would cost,” Cartlidge said.
Cartlidge added the submarines and ships promised were a “fantasy fleet” based on “fantasy funding”.
How fast is the UK building submarines?
The Royal Navy has nearly completed the introduction of all of its Astute-class SSNs, with five of the seven planned currently operational. A sixth (HMS Agamemnon) is undergoing water trials while a seventh (HMS Achilles ex Agincourt) is still in build.
Between the six boats structurally completed so far, it has taken an average of slightly over 128 months to build each submarine, from a low of nine years and five months (HMS Ambush), to an at present high of HMS Agamemnon, projected at 12 years and six months).
The time taken between commencement of Astute boat builds has varied widely, from a low of 506 days between Boat 2 (HMS Ambush) and Boat 3 (HMS Artful), to an astounding high of 1,761 days between Boat 6 (HMS Agamemnon) and Boat 7 (HMS Achilles ex Agincourt).
On average, there were 968.6 days between commencing each Astute submarine, or about 31.8 months.
Capacity at Barrow is stretched, with four submarines currently in build, these being three of the four Dreadnought-class ballistic missile submarines (SSBN) and the last of the Astute class. The fourth of the Dreadnought class, the future HMS King George VI, will likely take up the slot of the last Astute (HMS Achilles, ex Agincourt) currently in build.
BAE Systems’ Devonshire Dock Hall (DDH), located at its site in Barrow-in-Furness, is the home of all UK submarine manufacture. At some 260 metres (m) in length, with a width of 58m and 51m height, the DDH is an immense structure.
The combined length of an Astute SSN (97m) and future Dreadnought-class SSBN (153m) is 250m, just within the confines of the DDH. Little imagery is available of the interior of the DDH, although BAE Systems did release an image of three Astute SSNs in build, more or less side-by-side.
It should be noted that it is not known what impact, if any, the outbreak of a fire inside the DDH in 2024 will have on the completion of the SSNs and SSBNs currently underway.
Given the criticality of the Dreadnought programme and the need to replace the ageing Vanguard SSBNs, any delays caused by capacity upgrades to the DDH would be unwelcome, and potentially risk the availability of the UK’s continuous-at-sea nuclear deterrent.
Assuming existing Astute SSN build pace start to completion and the average time between each boat, it can be extrapolated that a 12-hull SSN-A/Fantasy class fleet would be ready by March 2068, if it got underway in 2029 in order to replace HMS Astute in the 2040 timeframe.
At the present build pace of the Astute class at BAE Systems Barrow-in-Furness site, it will take more than 39 years and two months to build the Royal Navy’s future SSN-A fleet.
Whatever the UK does, it will need to expedite submarine builds, with the first-in-class of the Astute boats, HMS Astute, commissioned into service in 2010. The preceding Trafalgar-class SSNs had an average service life of 30 years, which if the Astute class follow the same principle will see HMS Astute needing a replacement by 2040.
On 13 June, UK Defence Procurement Minister Maria Eagle stated in a parliamentary written response that the SSN-A programme was currently in the detailed design phase.
“The aim is to deliver the first UK submarines into service in the late 2030s to replace the current Astute-class vessels,” Eagle said.
Without expansion of DDH or BAE Systems’ facilities at Barrow, much will depend on the delivery of the Dreadnought SSBNs, which look likely to take around 15 years to complete. The build of HMS Dreadnought began in 2016, with the vessel expected to enter service in the early 2030s.
The gap from the start of construction of HMS Dreadnought to the second-in-class HMS Valiant was two years and 11 months, while the gap to the third-in-class HMS Warspite ran to three years and five months. Given this, it is likely that fourth-in-class HMS King George VI will begin build in late-2025 or early-2026.
This will mean that the Dreadnought progamme is still ongoing as the first of the new SSN-A class are built.
Where could the UK expand submarine production?
UK government statements in June indicate planned investment into the defence nuclear sector, including more than £6bn over the Spending Review period “to enable a transformation in the capacity, capability and productivity of the UK’s submarine industrial base, including at BAE Systems in Barrow and Rolls-Royce Submarines in Derby”.
Tellingly, no mention is made of additional sites to be used, which appears critical in reaching the almost preposterous target of one SSN-A every 18 months. If this is the case, then Barrow will have to generate a seven-fold increase in build time efficiency and manufacturing capacity.
Expanding the BAE Systems site in Barrow appears difficult, which is hemmed in by commercial lands to the north and residential houses to the south.
Naval shipyards are in short supply across the UK, even less so those able to accommodate nuclear submarines, either decommissioned or in-service.
One hypothetical possibility could be Babcock’s Rosyth shipyard, which has room to expand or utilise existing manufacturing capacity. The site currently builds surface warships for the Royal Navy (Type 31 frigates) and assembled the Queen Elizabeth-class aircraft carriers in the 2010s.
Rosyth is also home to the Submarine Dismantling Project, which is using the disassembly of HMS Swiftsure, a 1970s era SSN, as a case study to dispose of dozens of decommissioned UK submarines.
