The 114,500-tonne Costa Concordia luxury liner has been rotting on an Italian reef since last January, after a collision that killed 32 of the 4,229 passengers and crew on board and has left the ship stranded for nearly 16 months. Yesterday morning, a crew of more than 500 engineers finally righted the Costa Concordia in the single-largest maritime salvage operation of all time. Here's how they got it done.
The Costa Concordia has spent the last year and a half resting in about 65 feet of water, atop a pair of underwater granite peaks a few yards offshore, tilting 70 degrees to starboard. While roughly half of the ship remained above water, the entire wreck was dangerously close to the edge of the reef that sank it, which sits above a 230-foot deep trough that could submerge it entirely.
Yesterday, crews attempted the first of five phases needed to right the vessel so that it can be towed to a scrap yard and dismantled. A series of cement sacks and a steel platform had already been installed on the reef to stabilise the wreck, and a floating boom has been deployed to capture any remaining fuel, oil, or other hazardous liquids that might spill out as the ship is righted. Nearly 350 cubic meters of diesel, fuel, and other lubricants were offloaded to prevent an ecological catastrophe, should something go wrong.
"The size of the ship and its location make this the most challenging operation I've ever been involved in," Nick Sloane, chief salvage operator, told the Daily Mail. In fact, this is the largest recovery op ever attempted on a passenger ship.
The actual raising involves a complex series of ropes, pulleys, and hydraulic jacks. In addition, a series of 11 mammoth steel boxes, dubbed sponsons, some of which are 11-stories tall, have been welded to the port side (as you can see above). These boxes were being flooded with seawater to help entice the ship onto a more even keel. Crews figured this would occur without tearing the ship in two, which was a very real possibility. Engineers estimated that it will result in only slightly buckling the superstructure, however, nobody knew how firmly the ship was wedged into its perch or how much force would be required to free it.
“Once you start lifting her off the reef you have already gone beyond the point of no return,” Sloane, told the Telegraph last Friday. Following the first attempt, the Costa Concordia rolled off its granite peaks—its weakened bow braced by a pair of steel "blister tanks"—and onto an artificial reef constructed of six steel-cement platforms before it will be towed away and scrapped next spring.
In all, the project is expected to use more than 30,000 tonnes of steel in the construction of these platforms. This 14 month recovery project has already passed the €600m mark, with the project being paid for through Costa Crociere's insurance. [Daily Mail - Telegraph - Sky News - Chicago Tribune]