The head of the Royal Navy’s submarine programme has told the Guardian that his team discovered design faults, technical problems and flaws in the construction of the multibillion-pound Astute class boats, but said he was still confident it would enter service on time next year.

In a frank interview in which he spoke in detail for the first time about the challenges of launching the submarines, Admiral Simon Lister also admitted the military should not have boasted about the boats’ top speed.

It was not unusual, he said, for the first of a class to be “a difficult birth”, but he added that the Astute was now the most tested boat in the navy. Lister insisted that lessons were being learned and that changes were already being made to Astute’s sister boats, which are due to come into service over the next decade.

He said he was feeding these modifications into the blueprints now on the drawing board for the submarines, dubbed Successor, to carry the Trident replacement.

Lister said he wished none of the problems on the Astute had occurred, but they were being dealt with and safety had not been compromised. “I wish none of them had happened. I wish I could buy a submarine as if it was a Mercedes-Benz coming off the production line after 10 years of product development. It isn’t that.

“What I would say is that the speed and the quality of the activity to put things right is second to none. The ambition to bring Astute into service in perfect order so that she is able to enter service within three months of exiting the shipyard, if anyone thinks that’s possible, they would be mistaken. A nuclear submarine is a complex beast. It has many different disciplines. It is one of the most complex things man produces.”

Lister said it would be wrong for the military to claim the difficulties were just “stuff and nonsense and teething troubles”, but he said it would also be wrong for critics to write off what is the navy’s most technically advanced boat.

The Ministry of Defence has ordered seven Astute hunter-killer submarines that will cost up to £10bn and expects them to become the backbone of the fleet.

The programme has been hindered by delays and overspends since it was commissioned 15 years ago, and suffered embarrassment in 2010 when Astute was grounded off Scotland – a calamity that led to the commander being removed.

Last month, the Guardian revealed that Astute, which is coming to the end of three years of sea trials, was forced into an emergency surfacing when it sprang a leak, suffered from internal corrosion, and been fitted with equipment and materials of the wrong quality.

Since then the Guardian has discovered new issues. The MoD has admitted to problems with the trays that carry important cables controlling Astute’s sonar, which has led some of them to fray badly. During a recent test, Ambush – the second of the class and also built at BAE Systems in Barrow-in-Furness, Cumbria – flew its “Not Under Command” flag – which denotes that due to exceptional circumstances it is unable to manoeuvre properly.

Both boats are having to be equipped with an electronic chart system, after a report into the grounding of the Astute in 2010 ordered the upgrade.

Significantly, both have also suffered propulsion problems that have prevented them from reaching or exceeding the speed published by the MoD – 30 knots.

The Guardian has been told that the design is likely to restrict the top speed of all the boats, but the navy will not be drawn on the issue, saying it is a confidential matter. However, Lister insisted the Astute did not have to be a fast boat, and admitted the MoD should have been more cautious about discussing speed when the fleet was first commissioned.

“Is Astute a high-speed submarine? No sir. We have emphasised stealth over outright speed. That is an operational decision we have made, a trade-off, to achieve other capabilities. We haven’t designed this submarine to be quick, we have designed it to be quick enough. Whoever [in the MoD] put ‘this submarine goes at 30 knots’ didn’t understand that the top speed of a submarine is a classified matter and missed out ‘up to’ which is traditionally the formula.

“Because you have poked us, we want to say it [will go] more than 20 knots, which we can say with certainty without giving too much away to the enemy. We don’t reveal the top speed because it would give a potential enemy an advantage. It is a classified number.”

Lister said he had identified three sorts of problems with the Astute: flaws in design that only became apparent when testing started; equipment that broke down too easily; and some problems relating to poor construction at the shipyard.

“In the programme of testing over three years we have identified issues in all of those categories. And got on and fixed them. Is this normal? Where is this on the spectrum of scandalous waste of taxpayers’ money? Is this what we could expect, is this the normal endeavour of dragging any ship out of the dockyard? You will have to make your own mind up. [But] the programme of testing is on track and the submarine will enter service this coming year.

“Every aspect of that submarine has been tested to the limit. It is the most thoroughly tested submarine in the navy today. Point me to any submarine building yard that produces a first of class and I will show you a process that is extraordinarily challenging. The level of challenge in Astute I don’t think has been any more than in the level of challenge in the first of class in other submarines.”

He said he had not and would not compromise on safety, even if that meant further delays to the programme. “I buy these things, I set the pace, I place the demand on the company, I judge whether the product is right enough and good enough.

“My rule is the thing that gives is not safety, the thing that gives is time. Where the shipyard needs to learn to do something it is the schedule that is relaxed to enable that learning to take place. What gives? It is the schedule, which is why Ambush emerged from the dockyard later than planned.”

He added: “The first child has been a difficult birth. We have learned those lessons and every engineering development that we put into Astute has gone into or is going into Ambush. Astute as she emerged from the dockyard will be very different from the seventh one because we learn from Astute.”

Lister said he had 800 people on his Astute team and 1,000 working on the replacement for the Trident-carrying Vanguard class submarines. He said the navy was using the lessons from Astute to refine plans for Successor.

“My policy is to take every lesson I can from every quarter I can find it into the design of Successor and its manufacturing plan. I am having meetings about Successor and attempting to learn the lessons from other areas of the programme – including Astute. You would expect me to. That is what we do.

“I am not sitting down saying ‘Astute has been a failure we are not doing that again’. I am saying what must we learn from our experience on a daily basis in how we put Successor together. Astute is a superb submarine and is going to be the backbone of the fleet, the submarine flotilla, when she enters into service.”

Source – The Guardian