A new expert analysis of the Titanic disaster has concluded that the tragic sinking can be blamed on low-grade rivets that the ship's builders used on some parts of the liner.
Co-author Timothy Foecke said the company, Harland and Wolff of Belfast, needed to build the ship quickly and at reasonable cost, which may have compromised quality.
'Under the pressure to get these ships up, they ramped up the riveters, found materials from additional suppliers, and some was not of quality,' said Mr Foecke, who is a metallurgist at the US National Institute of Standards and Technology.
That the shipyard was building two other vessels at the same time added to the difficulty of getting the millions of rivets needed, he added.
More than 1,500 people died when the Titanic, advertised as an 'unsinkable' luxury liner, struck an iceberg on its maiden voyage in 1912 and went down in the North Atlantic less than three hours later.
'The company knowingly purchased weaker rivets, but I think they did it not knowing they would be purchasing something substandard enough that when they hit an iceberg their ship would sink,' said co-author Jennifer Hooper McCarty, who started researching the Titanic's rivets in 1999.
The company disputes the idea that inferior rivets were at fault. The theory has been around for years, but McCarty and Foecke's new book, 'What Really Sank the Titanic', outlines their extensive research into the H&W archives and surviving rivets from the Titanic.
Ms McCarty spent two years in Britain studying the company's archives and works on the training and working conditions of shipyard workers. She and Mr Foecke also studied engineering textbooks from the 1890s and early 1900s to learn more about shipbuilding practices and materials.
Mr Foecke said the main question was not whether the Titanic would sink after hitting the iceberg, but how fast the ship went down.
His analysis showed the builders used stronger steel rivets where they expected the greatest stress and weaker iron rivets for the stern and the bow, where they thought there would be less pressure, he said. But it was the ship's bow that struck the iceberg.
Harland and Wolff spokesman Joris Minne disputed the findings. 'We always say there was nothing wrong with the Titanic when it left here,' he said.
When the iceberg hit the Titanic, it scraped alongside the ship. Mr Foecke said this affected a number of seams in the bow and the weak rivets let go, putting more pressure on the strong rivets.
'Six compartments flooded. If the rivets were on average better quality, five compartments may have flooded and the ship would have stayed afloat longer and more people would have been saved,' Foecke said. 'If four compartments flooded, the ship may have limped to Halifax.'
Retired Harland and Wolff naval engineer David Livingstone, who has also researched the ship's sinking, has said their conclusions that the rivets were to blame for the sinking are 'misleading and incorrect' because they do not consider the ship's overall design and the historical context.
'You can't just look at the material and say it was substandard,' Livingstone said. 'Of course material from 100 years ago would be inferior to material today.'
He said he has found no document to support the argument that Harland and Wolff knowingly used substandard material.
He pointed out that the Olympic, a ship the company built at the same time using the same materials, had a long life with no troubles. The third vessel turned out in the early 1900s was attacked and sunk in World War I.
Contrary to Mr Foecke's theory, Mr Livingstone said, the Titanic did not go down fast compared to other ships that have sunk.
He said the Titanic did not capsize, as do most sinking ships, but maintained an even keel until the last moment, going down after about 2 1/2 hours when the weight of the water it took on became too much.
