Recycling

SS Gairsoppa recovery

May 21, 2012, 12:09 am
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Robotic deep sea image of the SS Gairsoppa's stern compass. Source: Odyssey Marine Exploration

The SS Gairsoppa recovery is a planned deep-sea operation in the North Atlantic Ocean, that is expected to retrieve the world's largest precious metals shipwreck salvage in history. On February 17, 1941 a German U-boat in 1941 sank this British merchant ship with its cargo of silver bullion with a present value of 130 - 150 million pounds sterling. Only recently in the summer of 2011 was the precise location of the shipwreck pinpointed, resting at a depth of about three miles.

Sunken wreckage of the SS Garisoppa.Source: Odyssey Marine Exploration

The SS Gairsoppa in service in the Atlantic.

The firm of Odyssey Marine Exploration has been awarded a contract from the government of the United Kingdom to recover the sunken treasure, which operation is to start in Spring, 2012. The cargo is known to have been transporting seven million ounces of silver from India to Liverpool, England. Odyssey will be allowed to keep 80 percent of the recovery value, with the government of the United Kingdom taking the balance.

The Shipwreck discovery

It was only during the summer of 2011 that the exact shipwreck location was found. Using sonar and deep-sea robotics, the salvage firm Odyssey Marine Exploration pinpointed the sunken vessel and recorded still and video imagery using high intensity illumination of the otherwise dark sea-bed; the wreckage lies in 4700 meters of water in the abyssal zone of the North Atlantic approximately 450 kilometers southwest of the Irish coast. Initial location of the wreckage was effected using side-scan sonar with operations being directed from the surface vessel Odyssey Explorer. In addition to the 7,000,000 ounce silver hoard, some gold is expected to be among the sunken treasure. Both bullion and coinage are thought to be present in the lost hoard.

In a subsequent phase, an unmanned submarine was deployed to delineate and photograph the detailed features of the eerie abyssal zone wreckage. Fantastic shapes of twisted iron hull-work was covered with barnacles and evidenced other types of sea life. Specific elements of the vessel remains were clear enough to provide a positive identification.

In the recovery process of Spring, 2012, other robotic techniques including specialized underwater cranes will be used to extract and lift the valuable cargo. Recovery project manager Andrew Craig has estimated the precious metal extraction process will require approximately three months.

The ship and its sinking

caption Location (red dot) of SS Gairsoppa shipwreck in North Atlantic.

As laid down at Newcastle in the year 1919, the SS Gairsoppa was 121.69 meters (m) in length, with a beam of 15.90 m. She had a depth of 8.66 m and a draught of 7.82 m. She was propelled by a 517 nhp (nominal horse power) triple expansion steam engine driving a single screw propeller. The engine was built by the Palmers company of Newcastle, England. It had cylinders of 69 centimeters (cm), 110 cm and 200 cm diameter by 1.2 m stroke to propel the ship at 19.4 kilometers/hour. when operating, the SS Gairsoppa was registered in the homeport of Glasgow, Scotland under registry to the British-India Steam Navigation Company

During World War II, the SS Gairsoppa was returning from a voyage to India in February, 1941, when the ship left its convoy in order to sail for the Bay of Galway. Unarmed and without escort, she was fired upon by the German U-101 boat under command of Korvettenkapitan Ernst Mengersen, who sank a total of over 67,000 tons of allied ships. The last reported position of the SS Gairsoppa was slightly to the west of the Celtic Sea shelf, southwest of the Irish coast. All 88 seamen perished, except for five European and two Lascar (south Asian) crew members. These survivors drifted ashore in a lifeboat two weeks after the sinking; moreover, their point of landing was on the Cornish coast at Caerthillian Cove under command of R.H.Ayres, the ranking survivor.

Deep-sea life that may be encountered

caption Hydrothermal vents such as this black-smoker are found
elsewhere in the deep Atlantic. Source: NOAA

As valuable as the recovery of seven million ounces of silver might be, the exploration of this unexplored part of the Abyssal zone of the North Atlantic may present even more precious scientific information on the lifeforms and geology of the ocean bottom where the SS Gairsoppa lies. The Abyssal zone is noted for its lack of nutrients, high oxygen content, and almost total lack of sunlight. In spite of these cold dark conditions, there are a remarkable array of fish, invertebrates, bacteria and other biota that inhabit this zone; examples of the fauna here are sea urchins and sea cucumbers who roam the abyssal plain, which itself is often studded with sea lilies and other deep sea flora.

The fauna tend to be translucent, red coloured, or even luminescent carnivores, with much of the food supply falling from the Mesopelagic zone and Bathypelagic zones above. Examples of these curious fauna are luminescent shrimps. Some of the permanent denizens of this deep ocean zone who are able to withstand the extremely high pressures of the Abyssal zone are Black swallower, Tripod fish, Deep-sea anglerfish and Giant squid.  Some larger abyssal fauna have underslung jaws adapted for sifting the benthic sand  and mud in order to scavenge for prey. But in this particular part of the North Atlantic it is likely that totally new species may be encountered, based upon the microtopography and microclimate of this particular geometric benthic environment. Higher in the water column are pelagic fishes such as blue whiting (Micromesistius poutassou) and Atlantic horse mackerel (Trachurus trachurus).

It is even possible that the shipwreck could be proximate to a deep-sea hydrothermal vent, a location where a natural sub-sea hot springs emerges, replete with unusual chemical composition. Such vents have been found elsewhere in the Atlantic bottoms and almost always harbor extremophile organisms, i.e. rare lifeforms adapted to harsh conditions of extremely hot temperatures and high concentrations of specific minerals or gases.

References

Glossary

Citation

Hogan, C. (2012). SS Gairsoppa recovery. Retrieved from http://www.eoearth.org/view/article/51cbf2187896bb431f6a7ceb

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