From the Daily News link above some explanation of how the ship is built and info on what happened:
http://www.dailymail.co.uk/news/art...ns-trapped-wreckage-capsized-cruise-ship.html
By Polly Dunbar - excerpts
However, as an industry, cruising has a safety record generally regarded as excellent. Over the past two decades, an estimated 90 million passengers have enjoyed a cruise without major incident. The overwhelming majority of deaths on cruise ships are from natual causes or suicides.
Although cruise ships appear to be top heavy, most of their weight is at the bottom, while the structure towards the top is designed to be comparatively lightweight.
According to Malcolm Latarche, editor of the global shipping magazine IHS Fairplay Solutions, the 950-ft Costa Concordia, which was built in 2005, was designed to standards comparable with ocean liners.
The Concordia was capable of travelling across the Atlantic, or anywhere in the world. It was considerably smaller than the Queen Mary II, but it was built to the same standards, he said.
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Mr Latarche believes the Concordia disaster may have been triggered by an electrical fault, which caused a loss of power in the ship and led it to crash into rocks.
Although the damage caused to the ship was severe, there are many safeguards in the design of a state of the art cruise ship to prevent it turning over. There is a second hull within the outer hull. Inside the inner hull there is a steel structure like an ice tray to contain the water and prevent it spreading through the ship.
In this case, the master rightly attempted to return it to the shore,
but it seems to have keeled over because it hit shallow water on the coast. An ocean cruise ship is not designed to float in 20ft of water. It needs much more than that to remain upright.
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