GIGLIO ISLAND, Italy -- Engineers on Monday succeeded in wresting the hull of the shipwrecked Costa Concordia from the Italian reef where it has been stuck since it capsized in January 2012, leaving them cautiously optimistic they can rotate the luxury liner upright and eventually tow it away.

Never before has such an enormous cruise ship been righted, and the crippled Concordia didn't budge for the first three hours after the operation began, engineer Sergio Girotto told reporters. But after some 6,000 tons of force were applied using a complex system of pulleys and counterweights, "we saw the detachment" from the reef thanks to undersea cameras, he said.

Girotto said the cameras did not immediately reveal any sign of the two bodies that were never recovered from among the 32 who died Jan. 13, 2012 when the Concordia slammed into a reef and capsized after the ship's captain steered the luxury liner too close to Giglio Island.

Images transmitted by robotic diving vehicles indicated that the submerged side of the hull had suffered "great deformation" from all its time on the granite seabed, battered by waves and compressed under the weight of the ship's 115,000 tons, Girotto said.

The initial operation to lift the Concordia from the reef moved the ship just 3 degrees toward vertical, leaving the vessel some 62 degrees shy of being pulled upright. While a seemingly small shift, the movement was significant enough to be visible: A few feet of slime-covered hull that had been underwater became visible above the waterline.

Engineers were waiting for the operation's completion before declaring success: The entire rotation was expected to last as long as 12 hours, with crews prepared to work into the night if need be.

So far, "rotation has gone according to predictions," and no appreciable pollution from inside the ship has spewed out, said Franco Gabrielli, chief of Italy's Civil Protection agency, which is overseeing the operation.

Giglio is part of a Tuscan archipelago in a marine sanctuary where dolphins romp and fish are plentiful.

The operation, known in nautical parlance as parbuckling, is a proven method to raise capsized vessels. The USS Oklahoma was parbuckled by the U.S. military in 1943 after the Japanese attack on Pearl Harbor.

But the 300-meter (1,000-foot), 115,000-ton Concordia has been described as the largest cruise ship ever to capsize and subsequently require the complex rotation so it can be towed away in one piece and dismantled for scrap.

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The operation involves engineers using remote controls to guide a synchronized leverage system of pulleys, counterweights and huge chains looped under the Concordia's carcass to delicately nudge the ship free from its rocky seabed and rotate it upright.

During the rotation process, a series of tanks fixed on the exposed side of the hull will be filled with water to help pull it down.

Once the ship is upright, engineers hope to attach an equal number of tanks filled with water on the other side to balance the ship, anchor it and stabilize it during the winter months. The flat-keeled hull itself will be resting on a false seabed some 30 meters (100 feet) underwater, made out of a platform and cement-filled sandbags that fill in the gaps of the sloping, jagged reef.

When it comes time to tow the ship in spring, the tanks will gradually be emptied of the water so the ship becomes buoyant enough to float off the seabed, working like a giant pair of water wings.

For over a year, residents of the fishing island have watched from shore as cranes and barges have moved into place to try to remove the hulk from their port. A few dozen gathered Monday morning on a breakwater to witness the operation getting underway, while others glimpsed it from shore as they went about their daily business.

One woman walking her dog near the harbor sported a T-shirt with "Keep Calm and Watch the Parbuckling Project" written across it in English. A variation on other T-shirts read: "Keep calm and think of Giglio Island." Gigliese, as locals call themselves, had raced to the aid of the survivors who staggered shivering from the sea that wintry night, bringing them blankets, warm clothing and invitations into their homes.

"There is a little tension now. The operation is very complex," said Giovanni Andolfi, a 63-year-old resident who spent his career at sea working on tankers and cruise ships and watched the operation from port.

Others watched from afar. Kevin Rebello, whose brother Russell was a waiter on the ship and was never found, said he was in constant touch with the project managers as he monitored news reports.

"I haven't slept since yesterday," he told The Associated Press in an interview in Rome. "It's taken 20 months. If it takes another 20 hours, for me it's worth the wait."

Rebello plans to travel to Giglio Island on Tuesday, even though he knows there's no certainty his brother's remains will be found. His hope is that someday he can bring his brother's remains home to Mumbai "to give him a decent burial.

"That's what me, my family, his wife and all of us are hoping for," he said.

Engineers have dismissed as "remote" the possibility that the Concordia might break apart and no longer be sound enough to be towed to the mainland to be turned into scrap. Should the Concordia break apart during the rotation, or spew out toxic materials as it is raised, absorbent barriers were set in place to catch any leaks.

The reef sliced a 70-meter-long (230-foot) gash into what is now the exposed side off the hull, letting seawater rush in. The resulting tilt was so drastic that many lifeboats couldn't be launched. Dozens of the 4,200 passengers and crew were plucked to safety by helicopters or jumped into the sea and swam to shore. Bodies of many of the dead were retrieved inside the ship, although two bodies were never found and might lie beneath the hulk.

The Concordia's captain is on trial on the mainland for alleged manslaughter, causing a shipwreck and abandoning the ship during the chaotic and delayed evacuation. Capt. Francesco Schettino claims the reef wasn't on the nautical charts for the liner's weeklong Mediterranean cruise.

Parbuckling was supposed to begin before dawn, but the operation was pushed back by an overnight storm that delayed the positioning of a barge near the wreckage that serves as the command control center. After the storm blew away, seas were calm.

Costa Crociere SpA, the Italian unit of Miami-based Carnival Corp., is picking up the tab for the parbuckling and its intricate preparation. The company puts the costs so far at 600 million euros ($800 million), though much of that will be passed onto its insurers.

Despite the disaster, locals have come to appreciate the crews who have spent more than a year working on the wreckage; they have mingled with locals and contributed to their economy, renting out hotel rooms and vacation apartments that would otherwise have gone vacant during the winter months.

Andolfi, the seaman, called the crews "the best brains in the field." But he was eager to see them finish.

"I would like Giglio to return to what it was before, a beautiful place of uncontaminated nature," he said.

MORE ON WEATHER.COM: Photos from Costa Concordia

The Costa Concordia cruise ship which ran aground off the Giglio island lies on its side, half-submerged into deeper waters, July 13, 2012. REUTERS/Remo Casilli