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A Royal Navy investigation into the grounding of one of its most advanced submarines has found a catalogue of errors led to the incident.

HMS Astute was grounded for 10 hours off the west coast of Scotland on 22 October 2010, during a boat-to-boat transfer training exercise.

<link> <caption>The report by the board of inquiry</caption> <url href="http://www.mod.uk/NR/rdonlyres/7A650FA3-9FFC-40F4-872E-6CB6D898DBE6/0/astute_grounding_si_report.pdf" platform="highweb"/> </link> found there was "no dedicated plan or briefing" for the transfer.

The Royal Navy said it accepted the results of the inquiry.

Rear Adm Ian Corder, head of the Submarine Service, said lessons had been learned.

Proximity of danger

The inquiry reveals that despite the exercise - which took place near Skye Bridge - being carried out in the dark, the submarine's prime radar was switched off.

It also found the Officer of the Watch (OOW) did not clearly plot the position of the transfer on the charts, and there were problems with the communications system on board the vessel.

"The root causes of the grounding were non-adherence to correct procedures for the planning and execution of the navigation combined, with a significant lack of appreciation by the OOW of the proximity of danger.

"However, a number of additional causal factors were present, including some deficiencies with equipment," the report said.

The £1bn nuclear-powered submarine was stuck for several hours on a silt bank, before being towed into deeper water by a coastguard tug.

The submarine's rudder was damaged during the grounding, but estimates of repair costs have yet to be completed.

The starboard foreplane of the vessel was also damaged during the recovery operation, after a collision between the tug and the submarine.

The captain of the submarine at the time - Cdr Andy Coles - was relieved of his command shortly after the incident.

Two other crew members have now also been disciplined, but further details on this will not be released by the Royal Navy.

Rear Adm Corder said he was confident the HMS Astute incident was not "indicative of wider failings" within the submarine service.

"A thorough review of submarine navigation and associated training has already been conducted, and I have ensured the inherent risks associated with such operations are kept as low as possible," he said.

The submarine was built by defence giant BAE Systems at Barrow-in-Furness, Cumbria, and is based at HMNB Clyde near Faslane.

HMS Astute hit the headlines again in April 2011, after Able Seaman Ryan Donovan shot dead Lt Cdr Ian Molyneux and injured a second crewman Lt Cdr Christopher Hodge on board the vessel.

Donovan fired six shots in the control room as local dignitaries were being given a tour of HMS Astute

He was sentenced to at least 25 years by a judge at Winchester Crown Court in September 2011.