HMS Agamemnon Completes First Trim Dive at BAE Systems’ Barrow Shipyard, Marking Major Milestone for UK’s Newest Nuclear Submarine

HMS Agamemnon Completes First Trim Dive at BAE Systems’ Barrow Shipyard, Marking Major Milestone for UK’s Newest Nuclear Submarine

(IN BRIEF) BAE Systems has announced the successful completion of the first trim dive of HMS Agamemnon, the UK’s newest Astute-class nuclear submarine, at its Barrow shipyard in Cumbria. The three-day exercise verified the submarine’s stability, safety, and system performance, marking a major step toward operational deployment with the Royal Navy. Executives from BAE Systems, the Submarine Delivery Agency, and the Royal Navy praised the achievement as a reflection of the industry’s engineering excellence and teamwork. HMS Agamemnon is the sixth of seven Astute-class submarines, built alongside the Dreadnought-class boats that will replace the Vanguard-class fleet responsible for the UK’s Continuous At Sea Deterrent. The success highlights the ongoing collaboration within the Defence Nuclear Enterprise and BAE Systems’ growing role in supporting the UK’s strategic and industrial defence ambitions.

(PRESS RELEASE) FARNBOROUGH, 13-Oct-2025 — /EuropaWire/ — The UK’s newest nuclear-powered attack submarine, HMS Agamemnon, has successfully completed its first submersion—known as a “trim dive”—at BAE Systems’ shipyard in Barrow-in-Furness, Cumbria. The achievement marks a significant step toward the submarine’s entry into service with the Royal Navy and reinforces Barrow’s historic role as the heart of the UK’s submarine design and construction capability.

The three-day trim dive took place in Devonshire Dock, where the 7,400-tonne, 97-metre-long vessel underwent extensive testing to verify its stability, buoyancy, and water-tight integrity. This complex phase ensures that HMS Agamemnon is safe and ready for operations before it departs Barrow to join the fleet at His Majesty’s Naval Base Clyde. The milestone comes just weeks after King Charles III officially commissioned the Astute-class submarine into the Royal Navy.

“This trim dive represents the culmination of months of meticulous planning, engineering, and teamwork,” said Pete Tumelty, Astute Programme Director at BAE Systems Submarines. “It is a proud moment for everyone involved, reflecting our ongoing commitment to national security and to Barrow’s world-class heritage as the centre of UK submarine innovation and construction.”

Commander David ‘Bing’ Crosby, HMS Agamemnon’s Commanding Officer, added: “This stage allows us to balance the submarine’s internal systems, verify its watertight integrity, and test onboard sensors and key equipment ahead of sea trials. Achieving this milestone required extensive preparation, and the entire team should be immensely proud of what they’ve accomplished.”

HMS Agamemnon is the sixth vessel in the Royal Navy’s Astute-class program, a fleet of seven nuclear-powered submarines designed and built by BAE Systems in partnership with the Submarine Delivery Agency (SDA) and the Defence Nuclear Enterprise. Alongside the Astute-class, BAE Systems is also building four Dreadnought-class submarines, which will replace the current Vanguard-class vessels that deliver the UK’s Continuous At Sea Deterrent (CASD)—the cornerstone of the nation’s nuclear defence strategy.

“The successful completion of HMS Agamemnon’s trim dive is a key step toward safely delivering capable and ready submarines to the Royal Navy,” said Henry Musgrave, Head of the Astute Delivery Team at the SDA. “It demonstrates the strength of collaboration across the Defence Nuclear Enterprise and our shared commitment to sustaining the UK’s nuclear deterrent.”

Design work is also underway on the AUKUS-class nuclear-powered submarines—a trilateral collaboration between the UK, the US, and Australia—further extending the capabilities and global partnerships that underpin the UK’s submarine enterprise.

To meet growing program demands, BAE Systems’ submarine workforce in Barrow has expanded significantly, increasing from 10,700 in 2023 to 15,000 today, with plans to reach 17,000 in the coming years. The growth underscores the scale and long-term importance of the UK’s submarine program for both national defence and the local economy.

Media contact:

Andrew McDowell
Head of Media, UK
Head Office
BAE Systems plc
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SOURCE: BAE Systems