Several factors contributed to the sinking of the Titanic, and many of them contributed to each other. In many aspects, the accident was both unavoidable, and totally avoidable.

Speed - Bruce Ismay reportedly persuaded Captain Smith to light the last two boilers to arrive in New York a day early, as a dramatic end to Smith's career. (The Titanic's maiden voyage was to be Smith's last command.) This would mean the Titanic was rushing through the area faster than it needed to be.

Watertight Bulkheads - As reported by dozens of periodicals at the time, the Titanic was equipped with 16 watertight compartments. Unfortunately, these bulkheads only extended 10 feet above water level. As the iceberg slid across the side of the ship, popping rivets and slicing holes along the way, the first four compartments filled up. Once a compartment filled up, the water spilled into the next, overflowing like a tilted ice-cube tray. The Titanic could concievably stay afloat with 4 compartments flooded, but the fifth compartment was flooded as well.

Inferior Construction - Several tests have been done on some of the Titanic's plates and rivets. The rivets were found to contain a high concentration of slag (the glassy residue remaining after the smelting of ore), therefore causing them to be quite weak, even becoming brittle in the icy water through which the Titanic was sailing. The Titanic's plates were also found to have a high ductile-to-brittle transition temperature, making them brittle in the water as well.

Damage - It was originally assumed that the iceberg tore a 300 foot gash into the side of the Titanic's hull. After several investigations, this was found to be untrue. In actuality, the iceberg snipped small holes into the hull at strategic points, causing five of the sixteen compartments to flood. The total damage to the ship is estimated to be approximately 12 square feet.

Other Factors - These factors also played a definite part in the sinking, working in concert with one another:

Since the binoculars for the crow's nest had been misplaced, the lookouts had to do without them. This, with a combination of there being no moon caused visibility to be extremely low. At 19:15 that night, the foreward lights were extinguished to aid the lookouts, making obstacles easier to spot. This didn't help much, however, due to:

  • No moon. Without a bright moon, there would be no light to reveal obstacles.
  • Calm seas. If the seas are calm, the water's surface is still and thus, no water breaks at the base of icebergs subsequently making them harder to spot.

When Fred Fleet finally spotted the iceberg, it was too late; the ship's rudder was far too small to corner that quickly. The Titanic was 882.5 feet long, and the rudder wasn't designed to accomodate that length while turning.

Fleet rang the nest's bell three times (the signal for an iceberg), and picked up the phone to the bridge. The ship was ordered hard to starboard with all engines at full astern, but since they were too close, there was the resulting collision. Plus, reversing the engines probably caused the ship to turn even slower than it would have, had the engines been set to full ahead. (Note: In 1912, ship's wheels were designed with a tiller effect. This means that turning the wheel to starboard (right) caused the ship's head to turn to port (left).) When the ship finally hit the iceberg, it had only turned 22 ½ degrees to port from when the command was engaged.

Whoop! Accipiter beat me to the punch...but here's some add'l info on the 'poor construction' factor.

Actually, one of the reasons the Titanic may have been so badly damaged by the iceberg - an event, by the way, that it was ostensibly designed to handle - was discovered in recent years. Careful analysis of metal samples brought back from the hull of the wreck showed that the steel used in its construction has several characteristics that rendered it unable to handle the situation.

For one thing, the steel has very high sulfur and oxygen content, along with low silicon. This means that it was only partially deoxygenated (or, in the parlance, semikilled). Steel is deoxygenated in order to improve its crystalline structure and strength as well as its ductility. An article in the Journal of Metallurgy (JOM) notes that steel processes in Britain around the time of the Titanic's construction used acid-lined open-hearth furnaces as well as basic-lined ones. The basic-lined furnaces would have reacted the basic liner with the impurities (sulfur, etc) and removed them; the acid lining failed to do so.

Another finding is that the steel from the Titanic hull was 'banded' fairly severely in the longitudinal axis. It is hypothesized that this happened due to the steel being hot rolled into plate; the deformation at high temperature caused the crystalline banding to occur perpendicular to the direction of the rolling process. The steel, therefore, has a much better performance under stress in the longitudinal direction; think of that packing tape with plastic threads in it. Although it is easy to separate it into long strips, it is extremely difficult to tear across. In the Titanic's case, the 'threads' ran along the hull from front to back. As we see in the iceberg damage, indeed, the damage to the plate is in a rough line from front to back which is fairly narrow. The hull buckled across the transverse lines.

The steel, chemically, appears to not have been dramatically sub-par for the era. However, the primary problem that the high sulfur, phosphorus and oxygen content causes is a shift in the ductile-brittle transform point. This is the level of heat energy in the steel at which the metal shifts from being ductile (bending and then tearing under stress)) to brittle (cracking under stress). This is expressed as the temperature at which this shift occurs. It is always possible to fracture the steel, but above the transform point it requires a substantially higher and faster energy input.

Modern steel shifts from ductile to brittle at approximately negative 25 to 30 degrees Celsius. This does not include special application steels, such as the HY100 rated steel used in submarine hulls, but the more general purpose steel used in ships, structures, etc. The Titanic sample, however, shows that it has a transform point of around 32 degrees for the longitudinal-cut sections and 56 degrees Celsius (more than 100 degrees Fahrenheit!) for the transverse sections (showing the effects of banding). Ergo, at temperatures below these points, impacts were much more likely to cause fracturing than ductile bending and tearing.

The water temperature the night the Titanic sank was estimated at negative 2 degrees Celsius. Draw your own conclusions.

Information for this writeup was drawn from the Journal of Metallurgy (50,1,1998), as well as various websites on the Titanic sinking. The assemblage of the information is my own.

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