UK plans to double nuclear submarine output to one boat every 18 months

In the Defence Nuclear Enterprise 2026 Annual Update to Parliament, the Ministry of Defence revealed it plans to double the output of submarines to one every 18 months. This excludes the AUKUS subs to be built in Australia using British-built reactors and other vital components.

The report states, “Through commitments made under the DIP, the government is investing in the shipbuilding and industrial capacity required to support an expanded SSN fleet, with the objective of achieving a drumbeat of one submarine every 18 months.”

The seven-strong Astute-class attack submarine fleet is nearing its end. HMS Agamemnon was delivered in 2025 and is currently undergoing pre-sea trials. The final boat, the Achilles, is under construction, with commissioning expected in 2028 or 2029.

The four-boat Dreadnought class is in full swing while the first steel on the first UK SSN-AUKUS submarine is expected to be cut in 2027, marking the start of production. The first SSN-AUKUS boat is scheduled to be delivered to the Royal Navy in the late 2030s.

Expanding facilities to boost nuclear submarine output

AUKUS submarines for the Royal Navy will be built at Barrow-in-Furness, while Australia will build its submarines at Osborne Naval Shipyard in South Australia.

Around £6 billion is earmarked to be invested over the Spending Review period. The investment is to focus on the critical BAE Systems’ submarine shipyard at Barrow-in-Furness and the Rolls-Royce Submarines’ Raynesway reactor facility near Derby. Other funding is for specialised equipment.

At Raynesway, work is already underway, including the recent groundbreaking of the major Primary Components and Operations Facility. Preparatory work at Ramsden Dock is also progressing, as are other efforts.

Work is also being done to improve site access and advanced prototyping facilities to enable a growing and highly skilled workforce to remain at the cutting edge of manufacturing technology.

The nuclear reactors for all of the AUKUS submarines will be built at Rolls-Royce Submarines’ Raynesway site, including those for the Australian submarines.

Building AUKUS alongside Dreadnought

First steel on the Dreadnought class was cut in 2016, with the type expected to enter service in the early 2030s. The first steel for Boat 4 in the Dreadnought class was cut in September 2025.

In July 2026, an £8.4 billion investment in industry to begin Delivery Phase 4 of the Dreadnought build programme was announced. This allows British yards to transition seamlessly from the Dreadnought to the AUKUS class.

The delivery rate will be achieved with the upcoming SSN-AUKUS attack submarine programme and will allow Britain to construct both these attack submarines and its fourth Dreadnought-class ballistic missile boats. This will set a new long-term production tempo for the Royal Navy.

Australia will acquire five of the AUKUS boats, while the UK is planning up to 12 to replace its Astute-class. A decision on the exact number of Royal Navy boats is expected before the programme’s Detailed Design and Long Lead phase ends in 2028.