Progress on the Royal Navy’s Dreadnought class submarine programme

The first of Britain’s new nuclear deterrent submarines, HMS Dreadnought has now been under construction for over 4 years. Although still relatively early days and available information is inevitably limited, some further details of the boat’s design and progress on this vast project have emerged since our first article on the subject in 2017.

First steel was cut for HMS Dreadnought in October 2016 and work on the second boat, HMS Valiant, was begun in September 2019. The third boat will be named HMS Warspite and the final boat, HMS King George VI. The first 3 names echo famous battleships of the 20th Century, although Warspite and Valiant were also used for two of the RN’s first-generation SSNs. King George VI is new to the RN, being named after Queen Elizabeth’s father who served in the navy where he saw action at Jutland in WWI.

The programme is currently in Delivery Phase 2 (DP2), intended to run until March 2021 and had seen expenditure of around £7Bn on the concept, assessment, and early delivery phases up to April 2019. The next 5 years will be the most expensive phase of the programme but the NAO says so far the project “remains within budget and on track for the first of class, HMS Dreadnought, to enter service in the early 2030s”. Unfortunately this week it became clear that the disruption caused by the pandemic has delayed the project by around 5 months and DP2 has subsequently been extended until March 2022. Over such a long programme there may be opportunities for the lost time to be made up. BAE Systems has worked very hard to create a COVID-safe working environment, with 95% of employees now back at work in Barrow.

The Dreadnought class are designed from the outset to have a service life of 35-40 years. This is a significant increase over their predecessors which should reduce through-life support costs but has contributed to the high initial price tag of £31Bn for the four vessels. A further £10Bn contingency fund has sensibly been allocated and has already been drawn on to reduce long-term costs and future risk, primarily by supporting industry through advanced orders and investment.

Design indication

The Dreadnought will have a very clean hull form without the missile compartment ‘hump’ of the Vanguard-class and will feature a distinctive raked fin. The forward hydroplanes have been located in a lower position (similar to the Trafalgar class boats) and will almost certainly be retractable for berthing the boat alongside.

The X-tail plane arrangement is also new to the RN and is more complex to design and manufacture but has several advantages. It reduces noise caused by turbulence as the water flow from behind the fin meets the vertical rudder. The planes can be smaller for the same control effect, further reducing noise. At high speed, they are also more stable because when a submarine turns, it rolls and the vertical rudder can start to act as a stern plane.

Dreadnought-Class-Submarine-2

Dreadnought is larger than the Vanguard-class, with a submerged displacement some 8% greater, totalling 17,200-tons. They will also be 3 metres longer than their predecessors, despite having fewer missile tubes. A bigger vessel allows for a larger and inherently safer reactor, further quieting technology and provides more room for improved crew comfort. This will be the first RN submarine designed from the outset to accommodate both male and female personnel and have a dedicated sickbay for the embarked doctor, a gym space, classroom and study areas on board as well as a new lighting system simulating day and night.

The boat will almost certainly have Integrated Electric Propulsion (IEP) and be driven by electric motor instead of the steam turbines used on RN nuclear submarines until now. The reactor provides steam for turbo generators that provide power for the motors and the rest of the boat’s requirements. Motors avoid the need for noisy reduction gears and allow more flexibility in the layout of the propulsion system. Most analysts assume that Dreadnought will not adopt a submarine shaftless drive (SSD) system or use Pseudo-magnetic Direct Drive (PDD) motors as the technology is not sufficiently mature and presents too much risk.

A multi-faceted industrial enterprise

Following on from its involvement in fabricating steel parts for the Astute-class boats, in October 2018 Cammell Laird was awarded a contract to manufacture items for the Dreadnoughts. The pressure hull itself is made entirely by BAES in Barrow as it demands specialist welders and processes to work with High Yield steel. CL will supply 29 non-pressure hull components for each boat including decks, bulkheads, ballast tanks and the fin structure. They will also make keels for the hull of sufficient strength to support the boat if resting on the seabed. Manufacturing has already begun, employing around 150 people for the next decade, with the last items due to be delivered by 2030. Completed components are transported by sea from Birkenhead direct to the yard at Barrow.

In a sensible move to reduce duplication of effort, the Dreadnought class share a common missile compartment design with the US Navy’s Columbia class SSBNs. Babcock in Rosyth and Bristol are involved in the manufacture of the Missile Tube Assemblies (MTAs) and since 2014, has won contracts for 57 MTAs. Another contract was secured in June 2020 for an additional 18, will bring the total made by Babcock to 75. The quad-pack of 4 tubes is about 80% fitted out with wiring and pipework before insertion into the pressure hull. Each Dreadnought boat will be fitted with 3 quad packs, giving 12 tubes while the USN Columbias will have 16 tubes.

Although procured together in a joint contract with General Dynamics Electrical Boat (GDEB), the initial tubes will mostly be supplied for the Dreadnought programme with later batches for Columbia. In June 2018 welding quality issues were identified with some of the tubes made by US contractor BWXT. The original technique for inspecting 100 inch-long welds was inadequate but later non-destructive testing by the USN inspectors identified the issue. This was not Babcock’s fault but it may delay supply of the MTAs to be installed in Dreadnought. As the heart of the ballistic missile submarine, this issue has demonstrated the wisdom of manufacturing the tubes well in advance of fitting to the boats.

The first 4 missile tubes were delivered to Barrow in April 2020 and welding into a Quad Pack is complete. Integration into a pressure hull section progressed well. is A further two tubes were delivered in July 2020.

The MTAs are far more complex than just metal tubes and Northrop Grumman is responsible for the complex launch system. The 58-tonne Trident missiles are ejected from the tubes by steam cannon. An explosive charge is used to vaporise a tank of water into steam. As the boat ‘hovers’ a few meters below the water, the expanding steam pressure forces the missile out of its launch tube with enough momentum for it to clear the water surface before the rockets ignite. Each tube has its own independent launch system that demands precision engineering to resist very high-pressure steam and safely eject a large nuclear-tipped rocket. The tubes must also allow maintenance access so the missiles can be inspected at sea.

Besides the launch tubes and their subsystems, an SSBN requires a sophisticated trim and compensation system to keep the boat stable during and after missile launch. As the missile leaves the tube, it has a substantial effect on the trim of the boat and water and air has to be rapidly moved between ballast tanks to ensure the submarine remains stationary in the hover position during successive launches. Consisting of a series of sensors and controls linked to valves, pipework, pumps, high-pressure air vessels and tanks, this is and one of many demanding engineering challenges. In 2018 it emerged the design and manufacture of this system for the Dreadnought class would cost £270m, more than 4 times the original estimate.

When companies are in the supply chain are faced with closure or financial difficulty, there is little alternative but for government to intervene to ensure continuity for the nuclear submarine programme. Funds have already been advanced have helped support Rolls Royce, the single most critical UK supplier to the project, who have a £480M contract to manufacturing the new-design PW3 reactor for the 4 boats.

Currently, the MoD is considering options for a take over of Sheffield Forgemasters who are specialist manufacturers of high-grade steel castings for use in submarines and are struggling. In November 2018 GE announced it plans to close its Power Conversion plant in Rugby and move operations to France but in May 2019 the MoD advanced its order for motors for the second batch of Type 26 frigates, averting the move. Not only did this make industrial and financial sense, but this may have been partly motivated by the fact that the Dreadnoughts are likely to be propelled by Advanced Induction Motors manufactured in Rugby.

In February 2020 it was not a surprise when Thales UK was awarded a £300M contract to supply the 2076 sonar system for the boats as well as and advanced optronic periscopes. 2076 is already at sea with the Astute-class boats and known to be one of the best submarine sonar systems in the world. It will be further developed and adapted for Dreadnought and comprises a suite of processors and underwater sensors including the active/passive bow sonar, a towed array, fire-control, environmental and obstacle avoidance sonars. It is unclear from the imagery if Dreadnought will have flank arrays like those carried by the Astutes.

Investment at Barrow

Constructing a ballistic missile submarine is considered to be an engineering project more demanding than building the space shuttle. Dreadnought is also the largest submarine ever built in Europe and to deliver the project, BAES needed to make a major £300M investment in supporting infrastructure. Work at Barrow has been on-going for several years and the main Central Yard Complex is complete and already in use. The pressure hull is constructed in sections or ‘rings’ which are delivered to the giant new Central Yard Facility. Here the rings are fitted out and will then be transported to the Devonshire Dock Hall (DDH) for assembly into a complete submarine.

BAES-Barrow

Principal features of BAE Systems yard at Barrow. The main new developments to support the Dreadnought project shown in colour. The Central Yard Complex (yellow) was completed in 2018 and is now in use. *The new quay and the DDH extension are currently under construction.

The DDH is currently completing the final 3 Astute-class boats and work is in an advanced stage to extend the hall for the needs of Dreadnought. The 260-metre DDH was completed in 1986 and covers 25,000m². In 2021 a six-year project will begin to entirely re-clad the vast exterior and add new skylights to increase natural light in the workspace.

Once a boat is complete and watertight it will be rolled out of the DDH onto the shiplift to be lowered into the dock. BAES plan to upgrade and extend the existing ship lift for Dreadnought, although the work will have to fit around the Astute boat roll-out schedule. Once in the water, the boat comes alongside at the Quay where the test and commissioning of boats is conducted. The nuclear reactor is taken critical for the first time during Power Range Testing. A new purpose-built jetty and associated buildings are being constructed by Jacobs Engineering. Before putting to sea, the submarine is submerged in Devonshire Dock for its first trial dive.

Recognising the importance of the skills base that must be developed and maintained for submarine construction, BAES has also invested £25M in an 8,300m² Central Training Facility to support around 1,000 craft and technical apprentices as well as the main workforce. The building houses replica submarine compartments, a VR training suite, 30 classrooms, 10 workshops and welfare facilities. A new 28,000m² off-site logistics facility, named the ‘Resolution Building’, to handle delivery and storage and of materials and thousands of components for the submarines was opened in 2016.

Counting down

Despite being one of the largest public spending projects and involving some of the UK’s finest engineering and manufacturing talent, the Dreadnought project must remain largely out of sight. Some contractual milestone announcements and some limited imagery will continue to emerge but the scale of the achievement will probably not be appreciated until the completed hull of Dreadnought is rolled out of the DDH in the mid-late 2020s. HMS Vanguard is currently completing her much delayed major refit and refuelling in Devonport but will be 37 years old by 2030 and in desperate need of replacement. There is no specific commitment to HMS Dreadnought’s in-service date other than “the early 2030s” but head of the MoD, Stephen Lovegrove said this week that his department has a “relentless focus” on delivering her on time.