A Royal Navy nuclear-powered submarine struck the bottom of the sea at more than 14 knots because of basic navigational errors made during a training exercise for three students on board.

Tracing paper over the submarine’s chart also covered vital information, including that the tidal rate at that point was 2.5 knots. The details are revealed in the official board of inquiry report into the grounding of HMS Trafalgarin October 2002, released under a freedom of information request.

Ninety seconds before the boat hit the seabed near the Isle of Skye, somebody realised what was about to happen and was recorded as saying: “We’re going to have to change course. This is too dangerous.”

The board of inquiry investigators failed to discover who had issued the warning, but it came too late and “at 0757 the submarine grounded, striking the bottom heavily on the port side forward . . . speed 14.7 knots.”

The report recorded: “On impact, the ship’s head was forced to starboard and there was a rapid deceleration, forcing most people to lose their balance and causing at least three minor injuries.”

Once he had recovered his balance, Commander Robert Fancy, the commanding officer, ordered the submarine to surface to check that the pressure hull had not been breached and to ensure that the nuclear reactor had suffered no damage. The reactor plant was unaffected, but the hull needed repairs costing £5 million.

The involvement of unsupervised student submariners in the navigation procedures and the use of tracing paper on the chart were criticised heavily by the board.

The three students, who were taking part in a submarine command course during the exercise, code-named Cockfight, had prepared a navigation plan that assumed that transit would be at periscope depth and “with frequent visual fixes”. But the plan was changed by the senior officers to test one of the trainees, Lieutenant-Commander Tim Green.

However, the students had not anticipated that HMS Trafalgar was going to go deep and at speed. “Consequently, it [the plan] was inadequate,” the report said.

The spring tidal rate was not properly taken into account when charting the course approaching a rocky islet, Fladdachuain, near the Isle of Skye. The report said that the information on the chart and general topography made it likely that the tidal stream would increase. But the speed of the submarine was overestimated and “no account was taken of the time needed to accelerate from four to eight knots. Untidy and inaccurate chartwork made calculations difficult,” it said.

The tracing paper had been used on the chart to protect it from being written on. But the report said “vital information” had been obscured. The use of tracing paper had been “a contributory factor” in previous groundings. The board said that the use of tracing paper should be strongly discouraged.

The navigation plan had been “flawed both in concept and execution”. Supervision of the chartwork had also been insufficient, the report said.

“The CO [commanding officer] did not appreciate the inaccuracy in tidal stream calculations, nor the importance it was to assume after going deep,” the board concluded.

HMS Trafalgar grounded “because of human error”. Had the commanding officer and his senior staff appreciated the dangers inherent in the navigation plan, they would have monitored more closely the submarine’s true position. “Nuclear submarines should only conduct training of this nature if the arrangements for navigational safety are infallible,” the board said.

Commander Fancy, who was in charge of navigation, and Commander Ian McGhie, who was responsible for the training course, were court-martialled and reprimanded for negligence.

Collisions galore

— HMS Nottingham ripped a 160ft gash in her hull when she crashed into Wolf Rock, a charted outcrop off the east coast of Australia, in 2002. The £300 million Type 42 destroyer almost sank after water flooded five of her compartments

— In 1941 the SS Politician grounded herself in the Hebrides with a quarter of a million bottles of Scotch among her cargo. Much of this was soon liberated by the islanders, forming the basis for the novel Whisky Galore!

— The USS Missouri ran aground in Chesapeake Bay in 1950, to the delight of Russian satirists. Several tugs were unable to free her and a new channel was dredged eventually to take her back to shipping lanes after 35 days

— The USS San Francisco, a nuclear submarine, crashed into an undersea mountain at its top speed of about 32 knots in 2005. One crew member was killed and 97 injured

Sources: Times archive; Celtic Spirit Whisky Journal; US Navy

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