GIGLIO, Italy—The 114,000-tonne Costa Concordia cruise liner, which had been lying on its side off the coast of Giglio since January 2012, has been uprighted in an unprecedented salvage maneuver that engineers hope they will never have to repeat. Rotating the 290-meter-long ship up to vertical, performed by salvage firm JVC Titan-Micoperi, took 19 hours—almost twice as long at the experts who designed the plan predicted. The ship had to be painstakingly raised 65 degrees to reach center, and it took eight hours to complete the first 10 degrees, nudging the ship off the rocks on which it was impaled. As seen on time-lapse video, the second half of the “parbuckling” operation took far less time than the first half.

After the successful operation, Titan director Capt. Richard Habib told Scientific American that parbuckling was the last choice for a salvage this size. When asked if he thought the operation would set the standard in maritime operation—just moments after the giant vessel successfully came to rest on its platform bed—Habib said, “I hope not. It’s much easier to blow them up.”

No doubt, Habib meant that the risk of failure is far too high to make parbuckling a standard in salvage. According to Nick Sloane, the salvage master for the project, the many engineers had planned for every possible worst-case scenario—from the ship breaking apart under its own weight to the platforms built on the seafloor to hold it crushing or slipping away. But there was one situation for which no plan could be made: the weather. Sloane said weather “is what I was most worried about.”

In fact, the evening before the parbuckling, a torrential rainstorm with high winds caused rough seas, which delayed the positioning of the control tower, setting back the start time of the operation on Monday morning by three hours. And because strong seas were forecast for the day after the operation was to be finished, Sloane said they rushed the final pulling maneuvers to make the ship upright, working through the dark Monday night. It was better to risk going too fast than be caught in a storm when the ship was balancing at a precarious angle. “Keeping the ship in such a vulnerable position for so long was worrying,” he said after the parbuckling was complete. “We knew the weather was changing, so we had to make it work before sunrise.”

The seas on Tuesday were extremely rough, causing some concern that toxic substances inside the ship could be knocked out into the water and carried quickly in the wind. Constant tests of both the water and air quality proved that no contamination from the vessel, which holds an estimated 20,000 tons of filthy water laced with cleaning chemicals, paint thinners and rotting food, had escaped.

Now that the Concordia is upright, the next phase of the operation can begin. In the coming weeks engineers will make a detailed scan of the badly damaged side of the ship that had been caught on the rocks. The sponsons, or flotation boxes, that will eventually be attached to the so-called broken side of the ship will have to be fairly flexible and move with the sea, Sloane said, in stark contrast to the boxes on the undamaged side, which are rigid and fixed. Each one will be tailor-made to fit one part of the undulating broken side, shipped to the site and fitted, which will not be complete until next spring. Only then can the engineers refloat the ship, which is now sunken in 30 meters of water. The giant vessel will rise up 22 meters from its current position, in a procedure that should be at least as spectacular as the parbuckling was. Securing the ship’s underbelly will then take three more weeks, meaning it will finally be towed away sometime next summer.