I love movies. While recently watching James Cameron’s Titanic, opinions and reviews aside, I wondered, “Did an iceberg really sink the Titanic?” As it turns out — surprisingly — that was a reasonable question.

We’ve all seen the movie. Big, “unsinkable” ship plows into an iceberg, resulting in a tragic loss of life. (Along with some inaccuracies from Cameron, but this isn’t the place for such things.) How big? The largest ship ever built at the time of her construction, the Titanic was nearly 900 ft. long, stood 25 stories high, and weighed 46,000 tons. How unsinkable? The Titanic’s design included 16 major watertight compartments that could be sealed-off in the event of a punctured hull. According to the ship’s builders, even worst-case — two ships colliding at sea — the Titanic could stay afloat for two to three days. On the night of April 14, 1912, however, the Titanic sank in a horrifying two hours and forty minutes — about the time it takes to see a movie in a theatre, if you count waiting in lines for tickets and expensive snacks.

Breaking News Update: An article just published Tuesday, December 6, 2005 says, ‘New evidence presented yesterday at the Woods Hole Oceanographic Institution suggests the luxury ocean liner may have broken into three pieces — not two — when it sank in 1912, meaning it would have gone down much, much faster after colliding with an iceberg in the North Atlantic. ”It was likely much more complex and much more terrifying and faster than we previously thought,” said Lynn Gardner, a spokeswoman for The History Channel, whose divers discovered extra pieces of the famous ship’s hull in August. ”There wasn’t any time.”‘ A new History Channel documentary is set to air on February 26, 2006.

How was the ship constructed? The ships (The Titanic had two sister ships. The RMS Titanic and the RMS Olympic were built at the same time; the third ship, the RMS Britannic, was built later.) were built at the modified (to handle ships of this size) Harland and Wolff shipyard in Belfast, Ireland. Design speed for these ships was 21-22 knots. Each outboard propeller was driven by a separate, four-cylinder reciprocating steam engine. The center prop was driven by a low-pressure steam turbine that used the exhaust steam from the two reciprocating engines. As a whole, the power package was rated at 51,000 indicated horsepower. As an interesting aside, what with contemporary discussions of fuel efficiency, the Titanic burned up to 650 tons of coal per day while underway — coal was moved from bunkers into furnaces by hand.

According to one of the sources listed below, “The Olympic was launched on October 20, 1910, and the Titanic on May 31, 1911. In the early 20th century, ships were constructed using wrought-iron rivets to attach steel plates to each other or to a steel frame. The frame itself was held together by similar rivets. Holes were punched at appropriate sites in the steel-frame members and plates for the insertion of the rivets. Each rivet was heated well into the austenite temperature region, inserted in the mated holes of the respective plates or frame members, and hydraulically squeezed to fill the holes and form a head. Three million rivets were used in the construction of the ship.”

According to another article referenced below, “On the moonless night of April 14, the ocean was very calm and still. At 11:40 p.m., Greenland time, the lookouts in the crow’s nest sighted an iceberg immediately ahead of the ship; the bridge was alerted. The duty officer ordered the ship hard to port and the engines reversed. In about 40 seconds, as the Titanic was beginning to respond to the change in course, it collided with an iceberg estimated to have a gross weight of 150,000-300,000 tons. The iceberg struck the Titanic near the bow on the starboard (right) side about 4 m above the keel. During the next 10 seconds, the iceberg raked the starboard side of the ship’s hull for about 100 m, damaging the hull plates and popping rivets, thus opening the first six of the 16 watertight compartments formed by the transverse bulkheads. Inspection shortly after the collision by Captain Edward Smith and Thomas Andrews, a managing director and chief designer for Harland and Wolff and chief designer of the Titanic revealed that the ship had been fatally damaged and could not survive long. At 2:20 a.m., April 15, 1912, the Titanic sank with the loss of more than 1,500 lives.”

Did the Titanic really plow into an iceberg? Of course. In some survivors’ accounts, however, they recalled hearing a loud, cracking noise when the ship hit the iceberg. Phil Leighly, a professor emeritus of metallurgical engineering at the University of Missouri-Rolla, said in 1985, “When steel breaks, you expect a groaning, not a cracking sound…unless the steel is brittle.”

Also, while all of the officers testified that the ship sank intact, some survivors and crew testified that there was a hull failure at the surface. Apparently, few questions regarding the ship’s structure were part of the American and British inquiries into the disaster. In contrast to that which was depicted in the movie, there was disagreement among survivors as to whether the ship broke into two parts or was intact as it sank. “On September 1, 1985, Robert Ballard found the Titanic in 3,700 m of water on the ocean floor. The ship had broken into two major sections, which are about 600 m apart. Between these two sections is a debris field containing broken pieces of steel hull and bulkhead plates, rivets that had been pulled out, dining room cutlery and chinaware, cabin and deck furniture, and other debris.”

Hmm. What about that “cracking” sound?

During an expedition to the wreckage in 1996, researchers brought back steel from the hull of the Titanic for metallurgical analysis. Later analyses revealed (Considerably more detail is available in below-referenced article, ‘The Royal Mail Ship Titanic: Did a Metallurgical Failure Cause a Night to Remember?’) the presence of relatively high amounts of phosphorous, oxygen, and sulfur—a combination which has the tendency to embrittle the steel at low temperatures.

Another article referenced below says, “To determine the steel’s mechanical properties, it was subjected to tensile testing, as well as the Charpy V-Notch Test, used to simulate rapid loading phenomena; the test used samples oriented both parallel and perpendicular to the original direction of the hull plate. The ductile-brittle transition temperature (using 20 lbs.-ft. for the test) was found to be 20°C in one direction and 30°C in the other, compared with — 15°C for a reference sample of modern A 36 steel — and a water temperature of — 2°C on the night the ship collided with the iceberg.” The Titanic steel was also shown to have approximately one-third the impact strength of modern steel. “When the Titanic samples were also examined with a scanning electron microscope, the grain structure of the steel was found to be very large; this coarse structure made it easier for cracks to propagate. Rivet holes were cold-punched, a method no longer allowed (they must now be drilled), nor were they reamed to remove microcracks.”

Some slam the engineering community for the Titanic disaster, alleging that steel’s low-temperature brittle fracture problem was ignored or unrecognized. That article continues, “Thirty years after the Titanic sank only because the water was about 15 degrees too cold, the U.S. Government built over 5,000 Warships with the same fundamental flaw. Of these 5,000 Warships, 1,000 suffered significant failures between 1942-1946 because of low temperatures, while 200 suffered serious fractures between 1942-1952.” No one may ever know exactly how many ships “just disappeared” in the North Atlantic and were falsely chalked up as lost to German U-Boat torpedo attacks due to low temperature brittle fractures. Some torpedoed ships may have even survived an attack, albeit damaged, without the hull shattering due to the low temperature brittle crack phenomenon.’ While the headline of that article (Cold Water Sinks Titanic) seems oddly accurate, the author rants about a government cover-up which, even to me, seems more than extreme.

While various sources seem to agree that the steel used to make the hull plates of the Titanic are inferior by today’s standards (and “would not be acceptable for any construction purposes and particularly not for ship construction”), agreement also exists among most sources that the hull plates of the Titanic were of the best steel available at the time.

“If the Titanic had not collided with the iceberg, it could have had a career of more than 20 years as the Olympic had. It was built of similar steel, in the same shipyard, and from the same design. The only difference was a big iceberg.”

So, what sank the Titanic? Bad engineering or construction? Brittle steel? An iceberg? Cold water? All of the above, or none of the above?

Sources and Other References

Secrets of Titanic’s Steel
http://www.prism-magazine.org/november/html/november_on_campus.htm

Causes and Effects of the Rapid Sinking
of the Titanic
http://www.writing.eng.vt.edu/uer/bassett.html#authorinfo

Cold Water Sinks Titanic
http://www.disastercity.com/Titanic/index.shtml

How Did the Titanic Sink?
http://www.memagazine.org/backissues/aug98/features/Titanic/Titanic.html

The Royal Mail Ship Titanic: Did a Metallurgical Failure Cause a Night to Remember?
http://www.tms.org/pubs/journals/JOM/9801/Felkins-9801.html

Testing the Titanic’s Steel
http://www.memagazine.org/backissues/aug98/features/Titanic/testing.html

The Science of Titanic, and How to Wreck the Shipwreck
http://starryskies.com/articles/dln/11-00/Titanic.pt1.html

Titanic’s Engineers
http://www.Titanic-Titanic.com/Titanic’s%20engineers.shtml