GIGLIO ISLAND, Italy - Engineers have declared the crippled Costa Concordia cruise ship completely upright after a 19-hour operation to pull it from its side where it capsized last year off Tuscany.

Shortly after 4 a.m. Tuesday, a foghorn rang out on Giglio Island and the head of Italy's Civil Protection agency, Franco Gabrielli, announced that the ship had reached vertical and that the operation to rotate it was complete.

Applause rang out among firefigters in the tent where Gabrielli and other project engineers made the announcement.

Officials said there was no apparent pollution in the waters around the ship as a result of the operation.

Using a vast system of steel cables and pulleys, maritime engineers on Monday gingerly winched the massive hull of the Costa Concordia off the reef where the cruise ship capsized near an Italian island in January 2012 and were poised to set it upright in the middle of the night.

After 15 hours of slower-than-expected progress in pulling the heavily listing luxury liner to an upright position, engineers said they finally hit the tipping point they eagerly were awaiting.

Shortly before midnight, the Concordia was raised by 25 degrees - after that, engineers said, the effect of gravity started giving the rotation a boost.

Then engineers quit operating the pulleys, and by using remote controls, carefully began opening valves to let seawater start filling huge ballast tanks that had been welded onto the already exposed side. The weight of the water in the tanks helped pull the cruise liner up much faster.

"We're in the final phase of rotation," said Franco Gabrielli, the Italian government official who is overseeing the operation. "We have passed the 24 degree mark and now are filling the tanks with water," he told journalists early Tuesday.

Originally, engineers had been confident complete rotation might take as little as 10 hours, and be reached by early evening Monday.

But the timetable quickly went off plan.

First, an unpredicted early morning thunderstorm pushed back the start time. Then the wreck resisted for three hours before it allowed itself to be wrested off the jagged rocks that were embedded into one side of the hull after the Concordia had hit another reef close to Giglio Island's coastline, took on water through a 76-yard-long gash, and eventually capsized a few hundred yards away onto another reef.

There it lay on its side until Monday's daring engineering operation pulled it free.

"Things are going like they should, but on a timetable that is dragging out," Gabrielli chief of Italy's Civil Protection Agency, said earlier on Monday.

Never before has such an enormous cruise ship been righted. Salvage workers struggled to overcome obstacle after obstacle as they slowly inched toward their goal of raising the crippled ship 65 degrees to the upright position.

At one point, some of the cables dragging the ship's hull upright went slack, forcing engineers to climb the hull to fix them.

The Concordia itself didn't budge for the first three hours after the operation began, engineer Sergio Girotto told reporters.

The initial operation to lift the ship moved it just 3 degrees toward vertical. After 10 hours, the crippled ship had edged upward by just under 13 degrees, a fraction of what had been expected.

After some 6,000 tons of force were applied - using a complex system of pulleys and counterweights - Girotto said "we saw the detachment" of the ship's hull from the reef thanks to undersea cameras.

At the waterline, a few feet of slime-covered ship that had been underwater slowly became visible, the first clear sign to spectators on land that the rotation strategy was working.

Thirty-two people died on Jan. 13, 2012, when the Concordia slammed into a reef and toppled half-submerged on its side after coming too close to Giglio Island. T

The listing of the liner 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. The bodies of many of the dead were retrieved inside the ship.

Officials said the underwater cameras did not immediately reveal any sign of the two bodies that were never recovered.

Engineers had dismissed as "remote" the possibility that the Concordia might break apart during the salvage operation but set out absorbent barriers to catch any leaks of toxic materials from the ship.

Images transmitted Monday by robotic diving vehicles indicated the submerged side of the cruise ship's 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.

Officials said so far no appreciable pollution from inside the ship had spewed out. Giglio Island is part of a Tuscan marine sanctuary where dolphins and fish are plentiful.

The salvage operation, known in nautical parlance as parbuckling, was used on the USS Oklahoma in 1943 after the Japanese attack on Pearl Harbor. But the 300-meter (1,000-foot) 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.

Engineers used remote controls to guide a synchronized system of pulleys, counterweights and huge chains that were looped under the Concordia's carcass to delicately nudge the ship free.

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 constructed some 30 meters (100 feet) underwater.

When it comes time to tow the ship away next spring, the tanks will gradually be emptied of the water. That will make the ship buoyant enough to float off the seabed, with the tanks acting like a giant pair of water wings.

Costa Crociere SpA, the Italian unit of Miami-based Carnival Corp., is picking up the tab for the operation, which it estimates so far at 600 million euros ($800 million). Much of that will be passed on to its insurers.

A few dozen island residents gathered Monday on a breakwater to witness the operation. One woman walking her dog sported a T-shirt with "Keep Calm and Watch the Parbuckling Project" written across it in English.

Others watched from afar. Kevin Rebello, whose brother Russel 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 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.

The Concordia's captain is on trial 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.