Scientists have discovered that the builder of the Titanic struggled for years to obtain enough rivets and riveters and ultimately settled on faulty materials that doomed the ship, which sank 96 years ago today.
The builder's own archive, the two scientists say, harbors evidence of a deadly mix of low-quality rivets and lofty ambition as the builder labored to construct the world's three biggest ships at once - the Titanic and two sisters, Olympic and Britannic.
For a decade, scientists have argued that the White Star Line ship went down fast after hitting the iceberg because the ship's builder used substandard rivets that popped their heads and let tons of icy sea water rush in. More than 1,500 people died.
When the safety of the rivets was first questioned 10 years ago, the builder ignored the accusation and said it did not have an archivist who could address the issue.
Historians say the new evidence uncovered in the archive of Harland & Wolff, in Belfast, Northern Ireland, settles the argument and finally solves the riddle of one of the most famous sinkings. The company now insists that findings are deeply flawed.
Each of the great ships under construction required 3 million rivets that acted like glue to hold everything together, and the scientists, in a new book, say the shortages peaked during Titanic's construction.
"The board was in crisis mode," Dr. Jennifer Hooper McCarty, one of the scientists who studied the archive, said in an interview. "It was constant stress. Every meeting it was, `There's problems with the rivets and we need to hire more people.'"
The team collected other clues from 48 Titanic rivets recovered from the wreck, modern tests, computer simulations, comparisons with century-old metals as well as careful documentation of what engineers and shipbuilders of that era considered state-of-the-art.
The scientists say the trouble began when the colossal plans forced Harland & Wolff to reach beyond its usual suppliers of rivet iron and include smaller forges, as disclosed in company and British government papers. Small forges tended to have less skill and experience.
Adding to the threat, the company, in buying iron for Titanic's rivets, ordered No. 3 bar, known as "best" - not No. 4, known as "best-best," the scientists found. They also discovered that shipbuilders of the day typically used No. 4 iron for anchors, chains and rivets.
So the liner, whose name was meant to be synonymous with opulence, in at least one instance relied on cheaper materials.
The scientists studied 48 rivets that divers recovered over two decades from the Titanic's resting place - two miles down in the North Atlantic - and found many to be riddled with high concentrations of slag. A glassy residue of smelting, slag can make rivets brittle and prone to fracture.
"Some material the company bought was not rivet-quality," said Dr. Timothy Foecke, of the National Institute of Standards and Technology, a federal agency in Gaithersburg.
The company also faced shortages of skilled riveters, according to archive papers.
In their research, the scientists found that good riveting took great skill. The iron had to be heated to a precise cherry red color and beaten by the right combination of hammer blows. Mediocre work could hide problems.
"Hand riveting was tricky," said McCarty, whose doctoral thesis at the Johns Hopkins University analyzed the Titanic's rivets.
Steel beckoned as a solution. Shipbuilders of the day were moving from iron to steel rivets, which were stronger. And machines could install them, improving workmanship and avoiding labor problems.
The rival Cunard line, the scientists found, had switched to steel rivets years before, using them, for instance, throughout the Lusitania.
The scientists discovered that Harland & Wolff also used steel rivets - but only on Titanic's central hull, where stresses were expected to be greatest. Iron rivets were chosen for the ship's stern and bow.
And the bow, as fate would have it, is where the iceberg struck. Studies of the wreck show that six seams opened up in the ship's bow plates. And the damage, Foecke noted, "ends close to where the rivets transition from iron to steel."
The scientists argue that better rivets would have probably kept the Titanic afloat long enough for rescuers to have arrived, saving hundreds of lives.
The metallurgists make their case, and detail their archive findings, in What Really Sank the Titanic, a new book by Citadel Press.