Onyx on the rocks, err ‘impact hydrography’

While the RN committed a number of sexy modern nuclear-powered attack submarines to the Falkland Islands conflict in 1982– and they proved effective in making the Argentine Navy return to port after HMS Conqueror sank the WWII-era cruiser ARA General Belgrano with 323 lost at sea (among the bulk of that service’s losses in terms of humans on the butcher’s bill)– there was one creepy little diesel boat poking around close to shore.

El Snorkel has a great article from Lt Cdr Andy Johnson Submarine, Commander HMS ONYX (S21) during the conflict. An Oberon-class submarine, she was but 241-feet long and weighed only 2,400-tons, smaller than a WWII U.S. Navy fleet boat.

Commissioned in 1967, she had a cramped crew of 6 officers and 62 men and made the slow transit from the UK some 8,000nm south to the Falklands MEZ with a special 5 man diving chamber 10 MK 24, 2 Mk 20 and 11 Mk 8 torpedoes aboard.

She stopped halfway at windswept Ascension and picked up a team of British frogmen, flown ahead to await their ride south.

At Ascension Island, 12 May 1982, ONYX boarded SAS and SBS special forces personnel and supported them during a series of operations. IWM photo

Her shallow operating depth allowed her to creep in close to shore for commando and surveillance work in relatively uncharted areas where a nuke boat would be hard pressed. Officially, “her ability to operate silently close inshore enabled her to play an important role. In addition to providing a submarine deterrent and enforcing the exclusion zone surrounding the Islands, ONYX undertook reconnaissance, taking periscope photographs of enemy installations and likely landing areas for Special Forces operations.”

And it was sometimes very hairy.

From Johnson:

An effort to complete a reconnaissance mission at short notice nearly ended the patrol. Many of the charts used to navigate in those waters had not changed significantly since James Cook had first drawn them. The occasional soundings he made at that time were undoubtedly adequate for his small sailing vessel. They scarcely matched the requirements of a 2,500 ton submarine two centuries later. In consequence, ONYX discovered an uncharted pinnacle of rock in a most dramatic fashion – by running in to it whilst dived. Although everyone reacted admirably and control was quickly regained, it is probably safe to say the only people on board who appeared really calm were our ‘guests’ from special forces. Not entirely due to their steel nerves – no-one had time to explain to them what had happened! This piece of ‘impact hydrography’ put two out of the six forward torpedo tubes out of action. This was serious enough in itself, but was made worse since the two affected tubes were those used exclusively for wire guided torpedoes. As a result, the fore-ends’ crew had to reorganise our full torpedo load. This was akin to playing solitaire. However, they first had to make a free ‘hole’ by moving tons of additional equipment out into the rest of the submarine. Even then there were still weapons weighing tons suspended in mid-air as the reshuffle continued.

The rest here.

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