Design and construction failures afflict HMS Astute


HMS Astute, the flagship for the Royal Navy's newest class of nuclear powered submarines, is reportedly too slow to carry out some of its duties, is subject to leaking and is beginning to corrode in places.

The submarine - acclaimed by the Navy as being the most capable and sophisticated British submarine ever to enter service – has been plagued with a catalogue of design problems and construction faults which are affecting its safety and performance, according to reports in the Guardian newspaper.

HMS Astute is unable to reach its intended top speed of 29 knots, meaning it would be unable to travel at speed to emergencies or away from attack, and unable to match the top speed of the Navy's proposed new aircraft carriers, which it is supposed to be able to escort and protect.

Other problems that have been reported include flooding during a routine dive, corrosion in places, concerns over the quality of nuclear reactor monitoring instruments, and flaws with the submarine's periscope.

During exercises earlier this year off the east coast of the United States a pipe carrying seawater from the back of the submarine to the reactor sprang a leak, forcing the submarine to undertake an emergency surfacing. An investigation revealed that a cap intended to be subject to the highest level of quality had been manufactured from substandard metal and had corroded, raising concerns that other parts of the submarine may also have been finished to below the specified quality.

Components of the submarine's nuclear reactor were also fitted to less than the required quality. A lead-lined water jacket surrounding the reactor core was fitted using metal of substandard quality, creating a risk that electrical charges in the lead could generate false readings in instruments monitoring the state of the reactor.

The submarine's CCTV-style periscope does not function well in rough seas, when the pictures are blurred by waves, and the reserve battery is also said to be far too small to power the submarine adequately.

A confidential Ministry of Defence memo obtained by the Guardian (available to download at the end of this article) warns that corrosion on Astute class submarines has been caused by cost-cutting and warns that quality controls have been ignored.

The memo states that corrosion is “a cause for major concern” and suggests that corrosion damage on the first two Astute class submarines, HMS Astute and HMS Ambush, is extensive. The damage means that “severe problems” can be expected in future and warns that as a result the submarines will have to spend more time than planned under repair.

The memo's author warns that, as a result of quality assurance failures, the first three Astute class submarines can be expected to suffer from similar problems and cautions “I am not sure whether it is already too late for the Boat 4.”

First commissioned 15 years ago, HMS Astute has yet to be accepted into service with the Navy – four years overdue and nearly £2 billion over budget. The problems mean that the Navy will either have to continue using ageing Trafalgar class submarines well beyond their design lives or have insufficient numbers of submarines available to conduct operations over part of the next decade.

The Ministry of Defence says that it is usual to experience problems when new types of ship enter service. “It is normal for first of class trials to identify areas where modifications are required and these are then incorporated into later vessels of the class”, said a spokesperson.

Writing in the Guardian Commander Steven Walker, commanding officer of HMS Astute, said “HMS Astute is a truly awesome submarine with a world-beating potential; her ship's company is second to none and that combination will allow me to take her from the 90% solution we have now to a fully operational platform in relatively short order”.


Download the Ministry of Defence memo on corrosion problems with Astute class submarines here:


A further news story in the 'Guardian' reports that as well as the faults listed above, new problems have been reported for Astute class submarines.

"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 - flew its "Not Under Command" flag – which denotes that due to exceptional circumstances it is unable to manoeuvre properly", the newspaper stated.

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