In a Barrow-in-Furness shipyard, Stuart Godden, the director of engineering for BAE Systems' submarines division in Cumbria, is narrating a slide show and comparing the UK's latest submarines programme – the Astute class – to Nasa's Space Shuttle programme. "They've got a crew of five to seven, we've got 97 or so," he says. "They go out for a couple of weeks, we go out for 90 days.They typically went on 100 missions, we've got 25 years to operate.

"In terms of environment, they're 200 miles up, we're hundreds of metres beneath the sea. It's very benign up there, because there's no pressure or corrosion, whereas it's very high pressure and very corrosive under the sea."

Eventually, he concedes some ground to the Shuttle programme: "Albeit, in getting there they have a very explosive force as they transit into outer space – clearly they're a hell of a lot faster than we are."


The control room, in which up to 15 crew work. The planesman steers and dives the sub from here Greg White

Godden's mission is to communicate the scale of what's been achieved with the delivery of Astute: the sub isn't a more complicated ship, it's a completely different realm of engineering. It will operate beneath the sea for months on end, during which time it may be attacked. Throughout its lifetime it will have a nuclear reactor on-board alongside missiles and close to 100 submariners.

Britain's submarines could previously remain at sea for a maximum of 15 years before refuelling. The new iteration will last for a quarter century – the only reason it will need to resurface is to take on food. But does Godden really think Astute was harder to build than a Space Shuttle? "They are two of the most challenging projects the world has ever undertaken," he says. "It's hard to be objective. All I'm trying to say is it's at least as complex from my perspective."

The Astute is the quietest submarine in the world. Almost every mission it will take part in will require stealth: eavesdropping in hostile waters, covertly delivering special forces (while submerged), tracking enemy vessels and aircraft, hunting enemy vessels and quietly hiding while waiting to launch its Tomahawk missiles (while submerged) at an onshore target that might be more than 1,500 kilometres away.


Although there are no definite dates, the seven Astute-class submarines are likely to be the Royal Navy's only attack submersibles in the next decade, taking over from the Swiftsure class (all decommissioned) and Trafalgar class (decommissioned within ten years). The only other submarines the Royal Navy will operate are the four nuclear-powered Vanguard-class boats, which currently carry Britain's nuclear weapons, and which will be superseded by the Successor class if the Government gives the go-ahead in 2016. Thirteen-hundred people are already working on Successor at Barrow's shipyard.

Audacious, the fourth of the Astute-class submarines Greg White

Godden, 44, has been director of the engineering function, which supports the Successor and Astute programmes, since 2010. He joined the Barrow shipyard as a mechanical-engineering graduate 23 years ago, when it was owned by Vickers. The yard has built all the Swiftsure, Trafalgar and Vanguard class, as well as the Royal Navy's first submarine, the HMS Holland 1, in 1901. Now it is owned by engineering firm BAE Systems. There are 3,500 people working on the Astute submarines, at a total cost of £10 billion. They have faced significant challenges. For instance, silencing a 97-metre-long, 7,400-tonne piece of metal with 100 people inside. Or equipping it with listening devices using arrays of hydrophones attached to all exterior surfaces of the submarine and some that trail behind when the sub is at sea (the loud pinging sonar you hear in films is rarely used because it reveals position).

"We created computer models of structures involved in the propulsion and pipework systems," says Godden, "and then modelled how we thought noise would be transmitted through those structures and pipe systems to the hull, and then obviously we tried to damp those noise paths to make the boat as quiet as we possibly could."


An Astute-class submarine in Devonshire Dock Hall in Cumbria. The sub has a 2076 sonar suite as powerful as 2,000 laptops. The sign says: "Lives Depend on Us Doing Our Job Right" Greg White

They also modelled being hit by a torpedo. The weapons used against submarines do not need to be highly explosive – their primary damage is caused by an air bubble created under the vessel after the explosion. The bubble lifts the ship or submarine and breaks its back. So the designers of Astute modelled the impact of the explosion and bubble, and created a hull which, Godden says, can withstand those forces.

The Ministry of Defence ordered the first three boats in 1997 but, according to a National Audit Office (NAO) report, the first six years of the Astute programme were plagued by technical problems caused by 3D CAD, which was being used on British submarines for the first time (before CAD, submarine designers used 2D drawings and a one-fifth-scale model). The NAO says the problems caused £1 billion in cost rises and nearly four years of delays. "I think there were several reasons for the overruns," Godden says. "It was the first time we had used CAD on a submarine and that did play a part, but it's not the only reason. We had a ten-year gap between [building] the Vanguard and the Astute class.

I would say the company and UK submarine enterprise lost a lot of skills in that gap, and Astute was very much about rebuilding the skills of the company. And actually I would say the UK's national capability in submarine building was rebuilt on Astute."

Once the design problems were overcome, construction started.

Slipways have gone – subs are now placed on a ship lift Greg White

The hull is made in steel sections which are then fitted with pipes, cables and other equipment. Everything is tested, then the sections are joined together and the systems are integrated and tested again. The command deck (where the captain will spend most time) is built separately. It has thousands of pipes and cables and is 20 metres long, ten metres wide, two storeys tall and weighs around 300-400 tonnes. It is slid into a section of the hull with a clearance of only millimetres which, Godden says, is "an engineering work of art".

"I admit that the night before we did it the first time round there were a few anxieties," he says. Once all testing is done the boat is taken on rails to a platform outside the main doors, where it is slowly lowered into the water. It is moored for more testing, before exiting the dock and entering the ocean. Of the seven boats planned, four are currently in the construction hall, one has yet to be started and the other two are already at sea – one was commissioned in August 2010, the other in March 2013. The first boat, Astute, has had a difficult time so far. It was grounded off the Isle of Skye in October 2010, causing what the Royal Navy described as "minor" damage. The captain was subsequently relieved of his command. In April 2011 a drunk crew member, Ryan Donovan, shot his fellow crew members on-board, killing one. He was sentenced to life in prison.

Dummy missiles in the weapons-stowage compartment Greg White

The build quality of the submarines has also prompted negative headlines in several national newspapers. WIRED is told that information regarding whether the sub is achieving its expected top speed is classified. Regarding reports that there have been leaks and corrosion, we are told the problems are fixed and a survey is being carried out to check that those fixes are adequate. Godden says the lessons learned are being applied to the remaining Astute submarines. "We have no prototypes [the cost of each craft is around £1 billion, so a prototype is too expensive]," he says. "Unlike cars or aeroplanes, for us the first of class is a vessel that goes into service with the Royal Navy. And there are no third-party design rules to turn to. Each nation holds its submarine-design rules sacred to themselves. There are no international standards."

Opened by Margaret Thatcher in 1987, the hall where the subs are made is huge: 268 metres long, 70 metres wide and 65 metres high. Up in the rafters are six huge gantry cranes. At each side of the hall are several levels of offices, gantries, cabins and stairs. Down in the middle of the hall are piles of equipment, material and the submarines -- boats three, four, five and six, all at different stages of completion. "We have full boat contracts for boats one, two, three and four," Godden says. "And we have long-lead orders for the early procurement of materials and early construction on five, six and seven."

BAE's Stuart Godden Greg White

Boat three (officially named Artful) is due to enter the water next year and is nearly complete. Its entire surface is covered with around 40,000 acoustic tiles (the exact number is a secret), which feel like rubber and dampen noise. Arrays of hydrophones bulge along its flanks. On top is the tower, which is reinforced in order to surface under ice caps (British crews have surfaced near the North Pole to play football, though someone has to stand watch with an SA80 rifle in case a polar bear wanders over).

Inside the boat, workers in white overalls work in the cramped space. Bunks are crammed in, the captain's cabin doesn't have its own toilet and every corridor is a crush of equipment. The design incorporates as little redundant space as possible – Godden refers to it as "packing density". There is little lighting. On the ceilings are oxygen points, to which the crew can attach masks if the atmosphere fails. There are several parts of the boat Wired is not allowed to see, including the nuclear reactor.

At the moment only the UK, US, France, Russia, China and India have nuclear powered submarines, and only the first four know how to build them (China and India bought theirs from Russia). This kind of technology provides enormous advantage because conventional submarines are powered by batteries, and to recharge those batteries requires a diesel engine, which needs oxygen. This means the submarine has to remain at periscope depth from the surface.

The battery also limits the range of conventional submarines – a nuclear powered sub has no curbs on its range because it refuels only every 25 years.

WIRED is told that the reactor is in a strong steel structure about the size of a large shed. Inside that structure is Uranium-235 with control rods in it. When those control rods are removed, the uranium atoms start to split and produce energy. The energy heats up water, which is carried in pipes as superheated steam, which heats water in a secondary system of pipes. The secondary steam is used to power the turbines, which power the propellors. Like everything in a sub, that process is complicated by its needing to be extremely quiet. The reactor system is cooled by seawater which must be continually pumped on-board. To keep the pumps quiet, they are mounted on rafts and damped. The same goes for the mechanism that flushes the toilet, as well as the machine that turns seawater into freshwater and then uses some of that freshwater to produce air. It's crucial that it's quiet. Sometimes the submarine operates in ultra-quiet mode for a few hours, when the biggest noise risk is the crew, who can be heard by other subs if they drop something or clank on steps, so they are sent to their bunks and forbidden to run water.

There are other factors which can give away a sub's position.

Carbon dioxide is discharged into the sea through a diffuser in order to ensure no bubbles are visible on the surface. Before starting its service at sea, the sub travels to Kings Bay naval base in Georgia in the US, where it passes through huge loops of metal to reduce its magnetic signature (after all the hammering on metalwork during construction, it's like a giant magnet when it enters the water). And the shape of the boat is designed to reduce the signature of its wake -- which can be detected and followed up to 12 hours later.

On the command deck there is an intercom as well as an old-fashioned voicepipe in case of electronic failure. There is no periscope; instead a mast rises for a few seconds, spins around, records images, then comes back down, so those in the command centre can review images on a screen.


Finally there is the magazine, which contains six torpedo tubes and racks of Spearfish torpedoes and Tomahawk missiles. The Royal Navy hasn't fired a torpedo in battle since the submarine HMS Conqueror sank the General Belgrano during the Falklands War. But British submarines have fired dozens of Tomahawk missiles during the wars in Kosovo, Afghanistan, Iraq and Libya.

"The UK needs armed forces," Godden says. "Providing the armed forces with the best equipment we can is important." Should the UK be involved in armed conflicts post-2020, expect Astute-class submarines to be in action, ever so quietly.

This article was originally published in February 2014.