The Secret of How the Titanic Sank

The Titanic left Queenstown harbor and sank while en route to the United States.

Low quality. More than 70 years passed before scientists were able to study the first physical evidence of the wreck. As luck would have it, the first piece of steel pulled up from the bottom seemed to put an end to the mystery. When the steel was placed in ice water and hit with a hammer, it shattered. For much of the 1990s, scientists thought this "brittle" steel was responsible for the massive flooding. Only recently has testing on other, bigger pieces of the ship disproved this theory. The original piece, scientists discovered, had been unusually weak, while the rest of Titanic's steel passed the tests. "We know now there was nothing wrong with the steel," says William Garzke, chairman of a forensics panel formed by the Society of Naval Architects and Marine Engineers to investigate the wreck.

Experts looking for explanations landed on another potentially weak link: The more than 3 million rivets holding the ship together. McCarty and Foecke began examining 48 rivets brought up from the wreck and found they contained high concentrations of "slag," a residue of smelting that can make metal fracture prone. Researching in the Harland & Wolff archives, they discovered that the shipbuilder's ambitious plans to build three large ships at the same time had put a huge strain on its shipyard. "Not because of cost, but because of time pressures, they started using lower-quality material to fill the gaps," says Foecke. This substandard iron was pounded by hand into the ship's bow and stern, where the large machines required to pound in steel rivets didn't fit. Steel rivets, meanwhile, which are much stronger than iron, were put in the more-accessible middle of the ship.

When the Titanic hit the iceberg, McCarty and Foecke say, the weaker iron rivets in the bow popped, opening seams in the hull—and hurrying the ship's demise. It's no accident, Foecke says, that the flooding stopped at the point in the hull where the steel rivets began.

Harland & Wolff, now an engineering and design firm, flatly rejects the notion that its rivets were weak. Tom McCluskie, the company's retired archivist, points out that Olympic, Titanic's sister ship, was riveted with the same iron and served without incident for 25 years, surviving several major collisions, including being rammed by a British cruiser. "Olympic deliberately rammed a German submarine during the First World War and cut it in half," says McCluskie. "She was plenty strong." The Britannic sank after hitting a mine during World War I. Both ships were strengthened after the Titanic disaster with double hulls and taller bulkheads, but their rivets were never changed.

Stronger rivets might have slowed the sinking process, but once water began flooding six of the Titanic's compartments, it was only a matter of time before the ship went down. Questions remain, though, about exactly how and why the ship ultimately broke apart and sank. In 2005, an expedition organized by Kohler and Chatterton found a new clue. Wandering away from the main wreckage site, they stumbled upon two large pieces of the ship's bottom on the ocean floor. Closer examination revealed the two hull sections had split exactly where the ship broke in two, making them a possible key to the mystery of the ship's final moments. Simon Mills, an Olympic-class-ship historian who advised the divers, calls the find "very likely the most interesting piece of Titanic research to be carried out in the last 20 years."

When Roger Long, a naval architect hired to accompany the expedition, began analyzing the edges of the hull pieces, he came to a surprising conclusion. It was impossible, he believed, for the ship to have broken up the way experts for two decades believed it did, with the stern rising up to a 45-degree angle before the ship's hull split. "There are a lot of very contradictory things you can see in the pieces," he says. "But the only scenario I could come up with to explain all of the contradictions was that the ship broke at a very shallow angle." Close examination of the pieces showed that they had been interrupted in the middle of tearing apart—a sign, Long says, that the ship was still at a low-enough angle (he estimates only 11 degrees) that its stern could regain buoyancy as it began to crack. If the back of the ship had been raised out of the water at a 45-degree angle, as depicted in Cameron's movie, once the stern tore off, nothing would have stopped it, and the hull pieces would have torn in two.