A leviathan task

On September 17,in the largest maritime salvage operation ever,engineers succeeded in righting the Costa Concordia

Published: September 29, 2013 12:34:26 am

* On September 17,in the largest maritime salvage operation ever,engineers succeeded in righting the Costa Concordia

* The ship had capsized when it struck a reef off the Tuscan island of Giglio in January 2012,leaving 32 people dead

* Cost of the salvage operation: $800 million

* The attempt to pull the cruise liner upright was a make-or-break engineering feat that has never been tried before

* Italy’s National Civil Protection Agency waited until sea and weather conditions were forecast for September 16 before attempting the task

The process

* Massive pulleys,cables and steel tanks were used by the 500-person salvage crew from 26 countries

* The crew rolled the 114,000-tonne vessel off the rocks

Known in nautical parlance as parbuckling,it was the first step in removing the 952-foot ship

* The Concordia was rotated onto giant platforms 30 metres below water level

* No ship this large or heavy has been parbuckled before

* Normally,crews blow up the ship or take it apart on site–a far cheaper route

* Officials say that wasn’t an option with the Concordia,because the ship was filled with noxious substances

* Also,the search for the two missing bodies of Maria Grazia Tricarichi and Russel Rebello continues

How does it work?

* To remove the ship in one piece,temporary steel post supports were driven into the shore and wrapped in chains so it wouldn’t sink further

* Six steel platforms were drilled into the ground floor,for the boat to land safely when flipped

* To tip the ship,parbuckling is used: hydraulic jacks pull on cables which connect the top of the caissons (water-filled retaining structures) on the platforms,raising it upright

* Once flipped,welders fastened another set of caissons to the damaged side for reinforcement,raising the ship afloat

* On September 15,towers were anchored onto the shore and fitted with computer-operated pulley-like wheels

* When the rotation began,the wheels guided thick cables and chains to pull the middle third of the ship

* More cables attached to the sponsons welded onto the port side of the ship pulled the Concordia from the top

Other marine salvage operations

* The largest recorded salvage operation was the raising of the German High Seas Fleet at Scapa Flow in 1919

* The USS California and USS West Virginia sank to the bottom of Pearl Harbour after being attacked by the Japanese in December 1941. They were re-floated and repaired

* In July 2002,HMS Nottingham suffered serious damage when she struck Wolf Rock near Lord Howe Island. She was towed,stern first to Newcastle,New South Wales,in August 2002 for minor repairs and consequently returned to the UK aboard the heavy lifting vessel MV Swan

* In July 2006,the Cougar Ace – a Japanese car carrier,packed with 4,700 Mazda cars and Isuzu trucks bound for North America—was stranded in the Pacific Ocean. The salvage team had to work for 24 days straight to save the vessel and its lucrative cargo

* In May 2007,the Odyssey Marine Exploration undertook the Black Swan Project and recovered an estimated $500 million in silver and gold coins from a wreck in the Atlantic Ocean. However,it was claimed by the Spanish government,leading to an ongoing legal dispute

Types of marine salvage processes

Offshore Salvage

These operations encompass stranded or sunken ships in open waters and are challenging as the ships have been exposed to the rough sea and weather. The procedure can take months

Harbour Salvage

To rescue stranded or sunken ships in sheltered water is easier as operations are not much affected by natural conditions

Cargo Salvage

Cargo can pose an imminent threat to marine environment. The priority is to get rid of hazardous elements and save expensive materials

Equipment Salvage

Another focus is on salvaging large machinery components like engines,turbines,driving systems by dissecting or destructing the hull

Shipwreck Salvage

This is a lower priority task. The objective is to disembarrass the water area of hazardous substances using the most practical and cheap method. One of the most common methods is to cut the hull into small sections

Afloat Salvage

When a ship is damaged but remains floating,the work involves damage control like hull welding,rebalancing ballast tanks,structural bracing and shifting cargo

Clearance salvage

These operations are carried out post a catastrophic event like a hurricane,tsunami or war. Ship wrecks are scavenged or removed

Nawaid Anjum

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