Twenty months ago, the luxury liner Costa Concordia slammed into a reef on Isola del Giglio near Italy, capsized and sank, killing 32 people and shocking the world with tales of cowardice by its captain and heroism from other crew members and locals who tried to save the lives of its passengers. Ever since, the ship has been stuck on its starboard side on the environmentally-delicate reef, a constant worry to the island’s residents and to maritime navigation. Yesterday, in a nearly day-long effort, engineers pulled off an amazing feat by righting the ship on a man-made platform through a process called “parbuckling,” the first stage of a long process that will eventually see the Costa Concordia towed to a salvage yard as scrap:

The capsized cruise liner Costa Concordia was sitting upright early Tuesday after the first step of an unprecedented effort to salvage the ill-fated ship.

In a lengthy process involving massive pulleys, cables and steel tanks, a salvage crew managed to roll the 114,000-ton vessel off the rocks where it ran aground 20 months ago.

“It was a perfect operation, I would say,” said Franco Porcellacchia, the head of the technical team for the cruise line Costa Crochiere, owned by American firm Carnival Cruises.

The effort began at 9 a.m. Monday (3 a.m. ET). By midnight, despite delays for thunderstorms and for slack in a crucial cable, the ship had been hauled off the rocks and upward about 25 degrees — far enough to start drawing water into the massive steel boxes attached to the exposed side of the hull, using the weight of that water to finish rolling the hulk onto a steel platform built off the sea floor.

It’s not over yet, though:

A great deal of work remains, Gabrielli cautioned. A tiny robotic submarine with surveillance cameras will survey the damaged side of the ship and create models needed in planning for the next phase of operations — the attachment of more sponsons to the starboard side.

Once those are installed, water will be pumped out of the sponsons to refloat the vessel. Organizers expect the ship won’t be towed away for dismantling until the summer of 2014.

CBS has time-lapse video of the operation:This makes it look easier than it was. The 952-foot-long cruise ship has significant structural damage, as can be seen in the photos showing the length of the righted ship. Even without that damage, attempting to spin a ship of that size can put incredible torque on the object that could easily rip it apart, especially with the added water weight in the flooded sections, unless calculated exactly performed precisely. In this case, that would have created an environmental disaster, with the ship full of toxic material from the decomposition of materials inside of it and the tons of spoiled food of a fully-stocked cruise ship that had just started its voyage the day it sank. It was those concerns that led to the parbuckling strategy, rather than the more usual demolition-on-site strategy normally employed in these cases.