Is It the Ballast Tank Imbalance or Swift Turn That Flipped the Vessel?

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Maritime experts say investigators look for problems that upset the giant cargo ship’s balance enough to make it fall onto its side, reports The Washington Post.

USCG investigation

As authorities try to answer why a cargo ship carrying 4,200 vehicles overturned on the Georgia coast, maritime experts say investigators will be looking for shifting cargo or other problems that upset the giant vessel’s balance enough to make it fall onto its side.

The U.S. Coast Guard is leading the investigation into what caused the South Korean ship Golden Ray to capsize early Sunday soon after it departed the Port of Brunswick, about 70 miles (112 kilometers) south of Savannah. 

The ship’s pilot and 23 crew members were all safely rescued, including four men trapped for 36 hours before they could be extracted through a hole drilled into the hull.

70-story building size ship

Measuring 656 feet (199 meters) long and 83 feet (25 meters) wide, the Golden Ray is roughly the size of a 70-story office building. 

Such vehicle carries tend to be ungainly and bulky, making them “like a floating shoebox,” said Joseph Murphy, a retired ship captain and professor of marine transportation at Massachusetts Maritime Institute.

Distribution of weight 

Keeping those ships upright requires a balancing act that involves 

  • distributing the weight of its cargo and fuel 
  • water in the ship’s ballast tanks, which fill to add weight and help lower a vessel’s center of gravity.

Consultants comment

Jim Staples, who worked 17 years as a captain aboard vehicle carriers similar to the Golden Ray and is now a maritime consultant. He said, “there’s a lot of different things that could have happened here.”

He added that it is clear that there’s a stability problem with the ship somewhere.

Staples said investigators will be asking 

  • whether vehicles in the cargo decks may have shifted and upset the ship’s balance?
  • whether they were lashed down properly?
  • were the ballast tanks holding enough weight to keep the vessel steady? 

Staples said crews sometimes wait to fill ballast tanks until they reach open seas to keep muddy water and marine animals from getting sucked into the tanks.

NSTB assigned to assist USCG

Coast Guard officials have declined to say what might have caused the Golden Ray to list and flip onto its side. 

The National Transportation Safety board has assigned investigators to assist them.

Weather not a factor

The weather doesn’t appear to be a factor. Hurricane Dorian brushed the Georgia coast with tropical-storm force winds four days before the Golden Ray overturned.

After the storm passed, the Army Corps of Engineers ruled out any obstructions that might impede ship traffic after inspecting the shipping channel between the Brunswick port and the Atlantic Ocean. 

National Weather Service records show clear skies and calm conditions during the time the ship left Brunswick.

Golden Ray made a turn before it capsized?

Coast Guard Capt. John Reed has said the Golden Ray was making a turn before it capsized. 

Satellite data recorded by the ship-tracking website Marine Traffic shows an inbound ship passing the Golden Ray around the same time it overturned in St. Simons Sound.

If the ship was turning at a high enough speed, the Golden Ray may have listed just enough to set off a chain reaction of events that ultimately pulled the ship down, said Brandon Taravella, a professor at the University of New Orleans’ school for naval architecture and marine engineering.

Notorious car carriers

Taravella said:

  • These car carriers are kind of notorious for cargo shifting inside.
  • If a hard turn is taken and then list at 10 degrees, the cars can shift and ship listing at 20 degrees. 
  • If there are openings in the deck and lean enough to take on water, it will be impossible to get it back upright.

Complex salvage operations

The Coast Guard is also working with salvage experts to decide how to remove the Golden Ray from the shipping channel.

“This is a complex salvage case,” Cmdr. Norm Witt told reporters Tuesday. “It is not going to be quick. I would say we’re going to measure this in weeks, if not months.”

Tough with added weight of vehicles inside

Some capsized ships have been salvaged by placing external ballast tanks beneath the side in the water, then filling them with air to push the ship upright and keep it buoyant, said Timothy McCoy, a professor at the University of Michigan’s naval architecture and marine engineering program. 

That might be tough to do with the Golden Ray, McCoy said, considering the added weight of more than 4,000 vehicles inside.

“They may have to cut it up in place. That’s the worst case scenario,” McCoy said. “It’s going to be a real challenge getting that one out of there.”

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Source: TheWashingtonPost

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