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September 16, 2013 1:33 pm
The remote controlled operation to bring the Costa Concordia cruise ship upright, known as “parbuckling”, is directed from a floating command centre and divided into three stages:
● Freeing the hull from the two spurs of rocks where it has been resting for 20 months, with the hull having moulded itself around the reef. More than three hours into the operation the team said the ship was starting to move free.
● Rotation continues with cables operated by strand jacks which gradually decrease their pull until sponsons – buoyancy chambers attached to the exposed port side – reach sea level and start to take in water. This occurs after the first 20 degrees of rotation.
● The final phase using the sponsons, filled with seawater by remote controlled valves. The weight of the water will push the ship down so that, once righted, it rests on the artificial support of six steel underwater platforms at a depth of 30 metres.
More than 30,000 tonnes of steel have been used in all components for the parbuckling and planned refloating – that is more than four times the weight of metal in the Eiffel Tower.
The six platforms to take the weight of the ship measure in total some 150m in length, supported by 21 pillars with a diameter of 1.6m and buried on average 9m in the granite seabed. An artificial seabed was built to steady the ship with 1,180 grout bags weighing more than 16,000 tonnes.
Fifty-six chains are used, each 58m long and weighing about 26 tonnes.
The exposed port side of the ship is fitted with 11 steel buoyancy chambers. Seven vertical sponsons have the height of a seven-storey building. Two horizontal sponsons would measure 11 storeys. Ingress of water into the sponsons when they reach the sea will help the rotation process.
Twenty months after it hit the rocks with the deaths of 32 passengers and crew, the Costa Concordia is once again the focus of media attention as salvage workers start the engineering feat of pulling the partially submerged cruise liner upright.
The operation, known as “parbuckling”, is the largest of its kind ever undertaken, with the ship measuring as long as three football pitches and about seven times the size of the Titanic.
Two blister tanks installed at the bow of the wreck provide buoyancy, measuring 23m long and 20m high. That structure weighs 1,700 tonnes.
Twenty-two vessels and eight barges are involved. The biggest, called Lone, is 160m long.
About 120 divers working on the project have made more than 15,000 dives.
More than 500 people of 26 nationalities have worked on the project, including 70 welders, carpenters and fitters, 50 engineers and 10 biologists.
The wreck is to be rotated 65 degrees to reach a vertical position.
Among the stores trapped inside the hull were tonnes of cheese, ice-cream tubs, pasta, onions, raw meat and more than 10,000 eggs. Perhaps in better condition, workers may find 18,000 bottles of wine and 1,000 bottles of olive oil.
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