Raising the Concordia - the biggest marine salvage operation ever - Telegraph For Captain Michael Walker, a tug boat commander from the Orkney Islands, the operation in the calm, sun-kissed waters of the Tyrrhenian Sea is a welcome change from the stormy North Sea, where he and his colleagues service off-shore windfarms. Yet with such an unprecedented exercise - the Concordia is the largest ever passenger shipwreck by tonnage in history - even he is not confident of success. "If it goes well, we'll be telling everyone about it," said Capt Walker, 27. But it's never been done before and nobody really knows whether it will work or not. I hope it does. Leaning out over the deck railings of his tug boat, Capt Walker told how he struggled to even comprehend the scale of the task ahead of him when he first saw the huge, gleaming white vessel lying on its side. "It was a surreal sight," he said. After arriving on the island it took me a few days to take it in. The Concordia, which was at the start of a week-long cruise of the Mediterranean, ran aground after its captain, Francesco Schettino, allegedly attempted a "sail-past" of Giglio's port, taking him too close to the shore. It rapidly took on water after being holed, and then keeled over on the island's shallow shores. A panic-stricken evacuation in darkness ensued, with terrified passengers and crew inching down the steeply-slanting hull while others leapt into the sea. The captain has been accused of abandoning ship before the chaotic evacuation was over, although he claims to have accidentally "tripped" into a lifeboat which then took him to shore. He appeared earlier this month at a pre-trial hearing in Tuscan city of Grosseto, where he faces accusations of manslaughter, abandoning ship and causing a shipwreck. The size of a large block of flats, the 114,500-ton Concordia is twice as heavy as the Titanic. Everything about the operation to rescue it is on an epic scale, and the task of lifting the stricken ship off the seabed, hauling it upright and towing it away for demolition is expected to cost at least £250 million. Specialists from a dozen countries are involved, but the UK is playing a prominent role. There are drilling crews from Cornwall, Welsh engineers and a contingent from Orkney and the Shetlands. Also with them are 30 crewmen from the Pioneer, a large construction support vessel from Middlesbrough. The Sunday Telegraph gained a rare glimpse of the operation when it was invited on board Capt Walker's tug, the Voe Earl, for a close-up inspection of the salvage effort. The Voe Earl has been helping to position a series of giant anchors, some of which can weigh 10 tons and measure 17ft, for the pontoon platforms which are working around the Concordia. The ship has been stabilised with 16 high-strength cables wrapped around its underbelly, which are weighted down by giant 12 anchor blocks weighting 35 ton each. Now the salvage teams will beging working on the even more challenging task of trying to tilt the ship back upright. Over dinner in a seaside restaurant one night, Capt Peter Bouchard, a British master mariner, demonstrated this process by laying a wine bottle horizontal on the table in front of him and rolling it a one-sixth turn. But while the principle is simple, the reality is rather harder. To start with, the salvage teams are drilling 26 holes in the granite seabed in which to place 6ft-wide pillars, which will support six specially-designed support platforms covering an area the size of a rugby pitch. This will create an area on to which the ship can be rolled without it fracturing its own own weight. For additional support, gaps between the platforms will be filled with sacks holding nearly 18,000 ton of cement. Access to the gaps is so awkward that the sacks will have to be filled by hand by a team of 100 divers. Assisted by seven underwater robots, they will manhandle hoses that will disgorge slurry cement into the bags. The ship will then be refloated with the aid of 15 enormous steel tanks which will be bolted onto its seaward-facing side, effectively acting as giant "arm bands." "The biggest are 32 metres long, which is the height of an 11-storey building," said Capt Nick Sloane, the South African senior salvage master in overall charge of the recovery effort. They weigh 500 tons and to get them lined up exactly so that we can weld them on is no small feat. The sheer toughness of the granite seabed, he added, was making the drilling task even harder. Once the tanks are bolted to the ship, they will then be attached to by cable to the support platform. The cables will then be slowly taughtened, while the tanks will be gradually filled with sea water, helping to drag the liner into an upright position. When it is upright, another 15 tanks will then be welded to the landward side of the ship. The seawater will then be pumped back out of the tanks, turning them from ballast to buoyancy aids and floating the ship free of the underwater platform. The divers will work in shifts around the clock, eating and sleeping on board the Pioneer, which serves British food, including kippers, Cornish pasties, and black pudding. If divers get into trouble underwater, there will be 10 decompression chambers on hand. "This operation is pushing the boundaries of marine technolog," said Capt Bouchard, who was recruited from Georgetown, Guyana, where he normally lives. There is no other job this size in the world. The Concordia will be taken to an as yet unspecified Italian port, where it will probably be demolished for scrap metal. The big fear is that the ship could break up before it can be floated away - a nightmare scenario that salvage experts insist will not happen. The removal operation is being conducted jointly by Titan, an American salvage firm, and Micoperi, an Italian offshore rig company, which were commissioned to do the job by Costa Cruises, the Italian owners of the Concordia. The removal of oil and diesel from the ship's fuel tanks earlier this year assuaged fears of an environmental disaster in the sea around Giglio, which lies in a marine conservation area populated by whales and dolphins. Still, experts are going to unusual lengths to protect marine life around the ship. The huge shadow cast by the Concordia has killed a large swathe of sea grass beneath it, putting about 200 giant clams at risk, so marine biologists relocated them to further down the coast. When drilling starts, two underwater tubes pump also compressed air into the water, creating a "a wall of bubbles" that prevents the noise disturbing the whales and dolphins. As the recovery operation is stepped up, many of those involved cannot help wondering how the accident could have happened in the first place. "With a ship of that size, you'd start to get nervous if you were within a couple of nautical miles of the island," said Ewan Anderson, another Shetlands salvager. For him to get so close... I just can't comprehend what he was thinking.