BAE Systems Dreadnought-class Ballistic Missile Submarine

History

The BAE Systems Dreadnought class is a British class of nuclear-powered ballistic missile submarines under construction for the Royal Navy. Four boats are planned to replace the Vanguard class and maintain the United Kingdom's continuous at-sea nuclear deterrent.

The submarines are being built at Barrow-in-Furness and will use Rolls-Royce PWR3 nuclear reactors. Each boat is designed to carry Trident II D5 submarine-launched ballistic missiles in a Common Missile Compartment developed jointly for the British Dreadnought and American Columbia programs.

Production of the lead submarine began in 2016. All four boats were under construction by 2026, but none had entered service. The British government expects HMS Dreadnought to become operational in the early 2030s.

Origins and approval

The United Kingdom has maintained continuous nuclear-deterrent patrols since April 1969. The four Vanguard-class submarines assumed this mission during the 1990s, but their planned service lives required the government to begin preparing a replacement. The official Dreadnought program factsheet describes four new submarines as the means of keeping one boat available for operational deployment at any time.

The replacement project was initially known as Successor. The government approved its initial assessment phase and procurement of long-lead materials in May 2011. On 18 July 2016, the House of Commons approved renewal of the Trident submarine force by 472 votes to 117. The lead boat was named HMS Dreadnought, and the class subsequently adopted the same name.

Construction

BAE Systems Submarines cut steel for HMS Dreadnought at Barrow-in-Furness on 6 October 2016. Construction of HMS Valiant began in September 2019, followed by HMS Warspite in February 2023 and HMS King George VI in September 2025.

The submarines are assembled from 16 large units. These are combined into aft, middle and forward mega-units before final assembly in the Devonshire Dock Hall. This modular method permits hull fabrication, installation of equipment and routing of cables and pipes to proceed concurrently. The pressure hull of HMS Dreadnought was completed in December 2022. Its keel-laying ceremony took place on 20 March 2025, although physical construction had already been underway for almost nine years.

The program is managed by the Submarine Delivery Agency. BAE Systems and Rolls-Royce are its principal industrial partners. Cammell Laird received work for non-pressure-hull sections, while Babcock is producing missile-tube assemblies in Rosyth and Bristol. General Dynamics Mission Systems supports the fire-control system, and Northrop Grumman supplies launcher-subsystem hardware for the Common Missile Compartment.

Funding

The government estimated the manufacturing cost of the four submarines at £31 billion, including inflation over the program, and established a separate £10 billion contingency. These figures do not represent the complete lifetime cost of the nuclear deterrent because missile support, warheads, operational infrastructure, maintenance and eventual decommissioning involve additional expenditure.

In 2026, the government awarded £8.4 billion for Delivery Phase 4. The package included £5.9 billion for BAE Systems to continue construction, integration and testing, with £2.5 billion assigned to propulsion equipment, structural assemblies, missile-compartment components and other long-lead items. The phase is intended to take HMS Dreadnought and HMS Valiant through sea trials while advancing the third and fourth boats. Contemporary reporting on the award is available from Naval News.

Design

Hull and arrangement

The Dreadnought class has a five-deck internal arrangement and a submerged displacement of approximately 17,200 tonnes. Its 153.6 m hull is longer and heavier than that of the Vanguard class. The design uses X-form stern control surfaces instead of a conventional cruciform arrangement. These surfaces provide control while supporting the submarine's acoustic and hydrodynamic requirements.

Construction and equipment arrangements emphasize noise reduction because concealment is essential to a ballistic missile submarine. Machinery isolation, acoustic treatments and a pump-jet propulsor are intended to reduce radiated noise. A technical overview published by Army Recognition also describes the streamlined hull, X-form stern surfaces and internal acoustic-control measures.

Propulsion and controls

Each submarine will be powered by a Rolls-Royce PWR3 pressurized-water reactor connected to turbo-electric machinery and a single pump-jet propulsor. The PWR3 was selected in place of an evolved PWR2 design because it offers improved safety, simpler operation and reduced maintenance requirements. Published descriptions state that it has about 30 percent fewer parts than its predecessor.

The reactor is intended to use a life-of-boat core, avoiding a planned nuclear refueling period during the submarine's service. Nuclear propulsion gives the class an operating range limited principally by food, maintenance needs and crew endurance rather than fuel capacity.

Movement will be controlled through BAE Systems' Active Vehicle Control Management system. This fly-by-wire arrangement transmits control commands electronically instead of relying entirely on direct mechanical connections.

Sensors and accommodation

The class will use the Thales Sonar 2076 integrated sonar system. In 2023, Thales Glasgow received a £193 million contract to provide optronic masts. These non-hull-penetrating sensors perform observation functions without a traditional optical periscope extending into the control room.

The planned complement is approximately 130. Accommodation includes separate quarters for female personnel, a gym, a classroom and a lighting system that simulates changes between day and night. The complement includes three chefs and a doctor, reflecting the duration and isolation of strategic patrols.

Strategic missile system

Each Dreadnought-class submarine will have 12 vertical missile tubes arranged in three four-tube modules. The Common Missile Compartment architecture is shared with the United States Navy's Columbia-class submarine program. It standardizes major elements of the missile section while allowing integration into the two countries' separate submarine designs.

The tubes will accommodate the UGM-133A Trident II D5 submarine-launched ballistic missile. The United Kingdom draws missiles from a common inventory maintained with the United States, but British authorities retain sovereign control over their nuclear warheads, targeting and any launch decision. The number of missiles and warheads carried on an operational patrol may be lower than the submarine's maximum tube capacity.

Defensive armament

Four 533 mm torpedo tubes will carry Spearfish heavyweight torpedoes. This armament provides a defensive capability against submarines and surface ships. It does not alter the class's primary role as a concealed strategic-deterrent platform.

Program status

All four planned submarines were under construction in 2026. HMS Dreadnought is expected to enter Royal Navy service in the early 2030s after completion, sea trials, crew certification and missile acceptance. Published accounts describe an intended service life of about 35 to 40 years, while the official government baseline states at least 30 years.

The program must overlap with continued operation of the aging Vanguard-class fleet. Maintaining four submarines allows one boat to patrol while the others undergo preparation, training or maintenance, but delays to either the replacement program or Vanguard maintenance can reduce operational flexibility.

• HMS Dreadnought: Lead boat. Construction began on 6 October 2016, and its keel-laying ceremony was held on 20 March 2025. Entry into service is expected in the early 2030s.
• HMS Valiant: Second boat. Construction began in September 2019.
• HMS Warspite: Third boat. Construction began on 9 February 2023.
• HMS King George VI: Fourth boat. Steel was cut on 22 September 2025.

Specifications (Dreadnought class)

General characteristics

• Type: Nuclear-powered ballistic missile submarine
• Builder: BAE Systems Submarines, Barrow-in-Furness
• Planned operator: Royal Navy
• Planned number: Four
• Length: 153.6 m (504 ft)
• Beam: Approximately 12.8 m (42 ft)
• Draft: Approximately 12 m (39 ft)
• Submerged displacement: Approximately 17,200 tonnes
• Decks: Five
• Complement: Approximately 130
• Intended service life: At least 30 years; other published descriptions give approximately 35 to 40 years

Propulsion and performance

• Reactor: One Rolls-Royce PWR3 pressurized-water reactor
• Drive: Turbo-electric propulsion
• Propulsor: One pump-jet
• Speed: At least 20 knots
• Range: Limited principally by food, maintenance requirements and crew endurance

Sensors

• Sonar: Thales Sonar 2076
• Observation: Thales optronic masts

Armament

• Strategic missiles: 12 launch tubes for Trident II D5 submarine-launched ballistic missiles
• Torpedoes: Four 533 mm tubes for Spearfish heavyweight torpedoes

The principal dimensions and armament are independently summarized by the SeaForces class reference and the detailed Dreadnought-class overview.

Related equipment

• Vanguard class: The Royal Navy ballistic missile submarine class that Dreadnought is intended to replace.
• Columbia class: United States Navy ballistic missile submarine class using the jointly developed Common Missile Compartment architecture.
• Trident II D5: Submarine-launched ballistic missile selected as the Dreadnought class's principal strategic weapon.
• Spearfish: British heavyweight torpedo planned for the class's defensive armament.