Navy’s newest submarine breaks down

Photo credit: Faslane Peace Camp


The Royal Navy's newest nuclear powered submarine, HMS Ambush, has broken down just days after a commissioning ceremony at which it was formally welcomed into the Navy.

Ambush, one of the troubled Astute class submarines, was spotted leaving its home base at Faslane in the Clyde Estuary at mid day on Wednesday (10 April).  The submarine reached the middle of the Gareloch but then halted.  According to a witness from Faslane Peace Camp, there was “loads of steam billowing out of the conning tower” and the submarine had “seemingly broken down in the middle of the loch”.  After around an hour the submarine slowly returned to its berth at Faslane escorted by tugs.  The incident was photographed by representatives of the Peace Camp, and images are available online here.

The Ministry of Defence issued the following statement about the incident:

"Following HMS Ambush’s maintenance period undertaken at Her Majesty’s Naval Base Clyde, an issue with a non-nuclear system was identified on Wednesday, and a decision was taken to return HMS Ambush to the Naval Base to allow remedial action to take place."

An MoD spokesperson said the problem “affected a variety of systems on the boat” and “was not safety related”, but refused to provide further details.  The submarine had been heading out for sea trials to test systems and sensors, but a decision was taken to return to Faslane to fix the problem instead of setting sail.

The spokesperson said that such issues were “business as usual” for sea trials.

Consulting nuclear engineer John Large suggested that the issue of steam from the submarine suggested that its nuclear reactor had probably been shut down.  “If there is a lot and a constant stream of steam being ejected from the vent at the top rear of the sail then probably it is the reactor dissipating heat through the flash evaporator, which means the reactor has been shut down and is rejecting the fuel core decay heat”, he said.

HMS Ambush was launched in December 2010 and was commissioned into service with the Royal Navy at a ceremony at Faslane at the beginning of March.  At the ceremony First Sea Lord Admiral Sir Mark Stanhope said that Astute class submarines “represent the cutting-edge of military technology and the future of UK submarine operations for many years to come”.  

The first of the Astute class submarines, HMS Astute, has yet to set sail on its first patrol from Faslane more than three years after being launched.

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