FALLIBLE SAFETY FEATURE: The Titanic was built with 16 major watertight compartments in its lower section designed to be sealed off in the event of a punctured hull. This sketch depicts the Titanic's bow section bulkheads. Image: Courtesy of Encyclopedia Titanica
The claim that the RMS Titanic was "practically unsinkable" may have been more a marketing tactic than a commentary on its engineering, but its prelaunch reputation of being impervious to the perils of the high seas has lingered for the past 100 years.
It is dangerous to cast engineering projects in such absolute terms—of course there had to be some combination of conditions under which the ocean liner would have failed. As elegant and grand as it was, however, the Titanic—like any other ship—was far from unsinkable.
At nearly 275 meters long with a gross weight of about 42,000 metric tons, the Titanic was the largest ship ever built at the time. It featured 16 major watertight compartments in its lower section that could be sealed off in the event of a punctured hull. Yet the luxury liner sank less than three hours after colliding with a massive iceberg in the North Atlantic, despite some estimates that it should have been able to stay afloat for as long as three days after an accident at sea.
The watertight compartments proved to be a fatal design flaw—one that James Cameron illustrated well early in his 1997 film recounting the fateful April night in 1912 when the Titanic sunk, taking about two thirds of her 2,200 passengers into the icy waters with her. The 90-meter gash in the Titanic's hull caused the ship to take on water near its bow, flooding six of the compartments. When enough water had penetrated the hull breach, the ship pitched forward at an angle that caused water from the individual compartments to spill over their bulkheads, inundating the front of the ship and sending the Titanic like a torpedo to the ocean bottom almost four kilometers below. Had the bulkheads been higher, or watertight at the top as well as the bottom, the water rushing into the hull might have been distributed more evenly, giving passengers more time to escape.
Ironically, builders of the Titanic were given a preview of how their ship might react to a hull breach several months before it even left port. On September 20, 1911, Titanic's sister ship, Olympic, was broadsided by the British warship HMS Hawke, which ripped away metal plates and riveted joints, leaving an 11-meter opening in the starboard side of the Olympic's hull. The collision caused the flooding of two of the Olympic's lower compartments, but the ship was able to make it back to port, perhaps contributing to the unsinkability myth.
Engineering and design are an important part of any construction project, but they are part of a larger system that includes the people that will manage and use the project's end product, whether it is an ocean liner, suspension bridge or spacecraft. Scientific American spoke with Henry Petroski, a professor of both civil engineering and history at Duke University and author of To Forgive Design: Understanding Failure, about the folly of believing a design is infallible, the Titanic's fatal flaws, and how even the best-engineered technology fails when a larger system breaks down.
[An edited transcript of the interview follows.]
It has been a century since the Titanic disaster. Will engineers ever be able to build an "unsinkable" ship?
The short answer is no. And anyway, it seems the claim that it was unsinkable didn't come from engineers but rather from advertisements for the Titanic. The ship had a lot of design features—such as the watertight compartments and their bulkheads—that may have led people to believe that it wouldn't sink.
Any design, whether it's for a ship or an airplane, must be done in anticipation of potential failures. In the case of the Titanic, the engineers would have been asking themselves: "What if we have a hole in the hull?" Well, water's going to come in. "How much water?" That depends on how big the hole is, so you have to make those calculations. You can always imagine a bigger hole or some worse condition.
What were the Titanic's greatest design flaws?
Probably the fact that the bulkheads didn't go higher, so that they weren't truly watertight and didn't actually compartmentalize water between the bulkheads. Other design elements meant to ensure passenger safety weren't adhered to. Although the ship was designed to carry enough lifeboats, it wasn't at the time of the accident, for example. That would be unheard of today. They had radio, which they called wireless back then, for calling other ships, but it was seen more as a novelty at the time, and ships turned them off after hours.
The Titanic also failed to incorporate a crucial safety feature available long before its maiden voyage. In the 1850s there was a British ship called the SS Great Eastern designed by Isambard Kingdom Brunel and built by John Scott Russell that featured a double hull. A double hull is a similar concept to bulkheads. Water comes in but you keep it from overtaking the interior of the hull. Generally speaking, the distance between the hulls is not that great, so the amount of water that gets in won't be that great. The debate over double hulls goes on to this day. After the Exxon Valdez oil spill there was a question as to whether all oil tankers should have double hulls.