Salvage master Capt. Nick Sloane still recalls the frantic radio call on the day in late July 2014 when the cruise ship Costa Concordia - improbably righted and afloat after 30 months on the rocks - began its slow journey from the island of Giglio back to the Italian mainland.

An Italian Coast Guard officer coming alongside the salvage convoy yelled at them that "they had no permission" to move the shape, after the extraordinary $850 million removal and refloating overseen by Sloane as slavage master for Houston-based Titan Salvage.

"l said, 'Do you want us to come back?' " Sloane recalled with a smile. It was just one more case of official indecision that plagued the biggest salvage and dive operation in history, as recounted by Sloane Wednesday at the WorkBoat Maintenance & Repair Conference and Expo in New Orleans.

The 950'x116'x27' Costa Concordia slammed into a pair of nearshore reefs off the Tuscan coast April 13, 2012, after Capt. Francesco Schettino set a heading for a close "show the flag" run at high speed. During a confused evacuation, 32 passengers and crew died. Schettino was found guilty of manslaughter in February and sentenced to 16 years in prison.

The disaster left the ship canted at a 70-degree angle just yards offshore, grounded and sunk on the reefs - the one thing holding the ship from slipping off into 120 feet of water. Sloane, a well-respected figure in the world of heavy salvage based in Cape Town, South Africa, was recovering a container ship wrecked in New Zealand when he got a message.

"I was just about to go home. Titan texted me and said, 'Are you busy? Are you interested in a wreck removal in the Mediterranean?'"

Sloane typed back: "Does it begin with a C?"

"Yes."

That began what would be dubbed The Parbuckling Project, rolling a half-submerged ship, twice the displacement of a World War II American Missouri-class battleship, back on its keel, with minimal environmental damage for removal and safe scrapping on the mainland.

In fact, with its flooded compartments Concordia was closer to 400,000 tons, Sloane said. The first step was anchoring the wreck so it would not be carried off the underwater cliff with winter storms. The more than 300-foot gully between the reefs was lined with grout cement bags, each about the size of a backyard aboveground pool and holdng some 24,000 metric tons in all, to provide support so the ship's back would not break.

The plan: use modified offshore steel platforms to build a shelf under the seaward port side of the ship, start attaching massive sponsons to that side and slowly roll it upright. Then, patching the severely holed starboard side, attach more sponsons, and refloat.

"The idea was to keep all the pollution inside the ship," Sloane said. It wasn't just fuel and oil, but the contents of a floating city of 4,200 people. The Tuscan isles are a marine park and critical to Italy's tourism infrastructure, an industry many locals said was already crippled by the hulking wreck.

Still, skepticism reigned.

"The divers were working. People looking from the beach saw nothing happening. The insurers got nervous. The government got nervous," Sloane said. "We had a meeting in Genoa where they screamed at me for two hours. I said, 'I didn't put the ship there, we're trying to help you.'"

A Norwegian engineer started a blog detailing his skepticism about the plan. Salvage planners felt the pressure, but it also made them re-analyze their plans over and over, he said.

Engineers cored the granite reefs to assess the strength of bedrock and how deep anchor pilings had to go. A chain with massive 5-1/3-inch/700-lb. links was wrapped around the ship.

Sponsons were fabricated in some of the five shipyards and seven fabricating sites engaged for the effort. Standing seven to 11 stories tall, the steel tanks were manufactured to handle two atmospheres of pressure during the refloating attempt.

As the starboard side emerged, workers sutured the hull with steel plates, completing work already started by divers who had used rebar to stop the cracks from spreading. On the now-secured ship, workers built false decks, plumb and level amid their tilted workspace, to hold workshops, tools and equipment.

The last set of sponsons was dubbed "the blister sisters" and built to wrap around Concordia's bow.  Sloane likened it to a neck brace; the engineers' analyses showed a real danger the bow might twist and split off without support during the parbuckling.

Amid continued doubts from many quarters, the ship went upright July 14 and left for Genoa 10 days later. Sloane said it might have been better going to a drydock at Palermo, for now it remains afloat at Genoa on its sponsons.

That worries Sloane. Concordia is still in chains, trussed like a salami, and those links are at 70 percent maximum tension. 

If they start to fail, others might follow, Sloane said. He'd even recommend submerging the hull -there's about 60 feet of water under the keel - and "take 50 percent off the tension."

Sloane's next job could take him to South Korea, where the government has bowed to popular demands to raise the ferry Sewol that sank one year ago with the loss of 300 lives, many of them students. He's been asked to join other experts being assembled by the government to come up with a strategy.

"She's penetrated 15 to 20 feet into the sea floor by way of the engine room. So they're not sure of what the breakout force will be" that's needed to start refloating Sewol, he said.

The Costa Concordia disaster showed how salvage is challeneged by the scale of today's shippjng.

"A meg-container ship carries 23,000 metric tons of oil. That's more than a small coastal tanker," Sloane said. "It's $1.5 billion in cargo. But the damage can be much worse." 

David Krapf has been editor of WorkBoat, the nation’s leading trade magazine for the inland and coastal waterways industry, since 1999. He is responsible for overseeing the editorial direction of the publication. Krapf has been in the publishing industry since 1987, beginning as a reporter and editor with daily and weekly newspapers in the Houston area. He also was the editor of a transportation industry daily in New Orleans before joining WorkBoat as a contributing editor in 1992. He has been covering the transportation industry since 1989, and has a degree in business administration from the State University of New York at Oswego, and also studied journalism at the University of Houston.