It is well established that the sinking of the Titanic was the result of an iceberg collision which fatally punctured the ship's front five watertight compartments. Less obvious however are the reasons for the collision itself (which occured on a clear night, and after the ship had received numerous ice warnings), the factors underlying the sheer extent of the damage sustained by the ship, and the reasons for the extreme loss of life.
Construction
Originally, historians thought the iceberg had cut a gash into Titanic's hull. Since the part of the ship that the iceberg damaged is now buried, scientists used sonar to examine the area and discovered the iceberg had caused the hull to buckle, allowing water to enter Titanic between her steel plates.
A detailed analysis of small pieces of the steel plating from the Titanic's wreck hull found that it was of a metallurgy that loses its elasticity and becomes brittle in cold or icy water, leaving it vulnerable to dent-induced ruptures. The pieces of steel were found to have very high content of phosphorus and sulphur (4x and 2x respectively, compared with modern steel), with manganese-sulphur ratio of 6.8:1 (compared with over 200:1 ratio for modern steels). High content of phosphorus initiates fractures, sulphur forms grains of iron sulphide that facilitate propagation of cracks, and lack of manganese makes the steel less ductile. The recovered samples were found to be undergoing ductile-brittle transition in temperatures of 90 °F (32 °C) for longitudinal samples and 133 °F (56 °C) for transversal samples, compared with transition temperature of −17 °F (−27 °C) common for modern steels: modern steel would only become so brittle in between −76 °F and −94 °F (−60 °C and −70 °C). The Titanic's steel, although "probably the best plain carbon ship plate available at the time", was thus unsuitable for use at low temperatures.[72] The anisotropy was probably caused by hot rolling influencing the orientation of the sulphide stringer inclusions. The steel was probably produced in the acid-lined, open-hearth furnaces in Glasgow, which would explain the high content of phosphorus and sulphur, even for the time.[72][73]
Another factor was the rivets holding the hull together, which were much more fragile than once thought.[73][74] From 48 rivets recovered from the hull of the Titanic, scientists found many to be riddled with high concentrations of slag. A glassy residue of smelting, slag can make rivets brittle and prone to fracture. Records from the archive of the builder show that the ship's builder ordered No. 3 iron bar, known as "best" — not No. 4, known as "best-best", for its rivets, although shipbuilders at that time typically used No. 4 iron for rivets. The company also had shortages of skilled riveters, particularly important for hand riveting, which took great skill: the iron had to be heated to a precise colour and shaped by the right combination of hammer blows. The company used steel rivets, which were stronger and could be installed by machine, on the central hull, where stresses were expected to be greatest, using iron rivets for the stern and bow.[73] Rivets of "best best" iron had a tensile strength approximately 80% of that of steel, "best" iron some 73%.[75] Despite this, the most extensive and finally fatal damage Titanic sustained at boiler rooms No. 5 & 6 was done in an area where steel rivets were used.
Rudder construction and turning ability
Although Titanic's rudder met the mandated dimensional requirements for a ship her size, the rudder's design was hardly state-of-the-art. According to research by BBC History: "Her stern, with its high graceful counter and long thin rudder, was an exact copy of an 18th-century sailing ship...a perfect example of the lack of technical development. Compared with the rudder design of the Cunarders, Titanic's was a fraction of the size. No account was made for advances in scale and little thought was given to how a ship, 852 feet in length, [sic] might turn in an emergency or avoid collision with an iceberg. This was Titanic's Achilles heel."[76] A more objective assessment of the rudder provision compares it with the legal requirement of the time: the area had to be within a range of 1.5% and 5% of the hull's underwater profile and, at 1.9%, the Titanic was at the low end of the range. However, the tall rudder design was more effective at the vessel's designed cruising speed; short, square rudders were more suitable for low-speed manoeuvring.[77]
Perhaps more fatal to the design of the Titanic was her triple screw engine configuration, which had reciprocating steam engines driving her wing propellers, and a steam turbine driving her centre propeller. The reciprocating engines were reversible, while the turbine was not. According to subsequent evidence from Fourth Officer Joseph Boxhall, who entered the bridge just after the collision, First Officer Murdoch had set the engine room telegraph to reverse the engines to avoid the iceberg,[28] thus handicapping the turning ability of the ship. Because the centre turbine could not reverse during the "full speed astern" manoeuvre, it was simply stopped. Since the centre propeller was positioned forward of the ship's rudder, the effectiveness of that rudder would have been greatly reduced: had Murdoch simply turned the ship while maintaining her forward speed, the Titanic might have missed the iceberg with metres to spare.[78] Another survivor, Frederick Scott, an engine room worker, gave contrary evidence: he recalled that at his station in the engine room all four sets of telegraphs had changed to "Stop", but not until after the collision.[29]
Orientation of impact
It has been speculated that the ship could have been saved if she had rammed the iceberg head on.[79][80] It is hypothesised that if Titanic had not altered her course at all and instead collided head first with the iceberg, the impact would have been taken by the naturally stronger bow and damage would have affected only one or two forward compartments. This would have disabled her, and possibly caused casualties among the passengers near the bow, but probably would not have resulted in sinking since Titanic was designed to float with the first four compartments flooded. Instead, the glancing blow to the starboard side caused buckling in the hull plates along the first five compartments, more than the ship's designers had allowed for.
Adverse weather conditions
The weather conditions for the Atlantic at the time of the collision were unusual because there was a flat calm sea, without wind or swell. In addition, it was a moonless night. Under normal sea conditions in the area of the collision, waves would have broken over the base of an iceberg, assisting in the location of icebergs even on a moonless night.
Excessive speed
The conclusion of the British Inquiry into the sinking was “that the loss of the said ship was due to collision with an iceberg, brought about by the excessive speed at which the ship was being navigated”. At the time of the collision it is thought that the Titanic was at her normal cruising speed of about 22 knots, which was less than her top speed of around 24 knots. At the time it was common (but not universal) practice to maintain normal speed in areas where icebergs were expected. It was thought that any iceberg large enough to damage the ship would be seen in sufficient time to be avoided.
After the sinking the British Board of Trade introduced regulations instructing vessels to moderate their speed if they were expecting to encounter icebergs.[citation needed] It is often alleged that J. Bruce Ismay instructed or encouraged Captain Smith to increase speed in order to make an early landfall, and it is a common feature in popular representations of the disaster, such as the 1997 film, Titanic [81] There is little evidence for this having happened, and it is disputed by many.[82][83]
Insufficient lifeboats
No single aspect regarding the huge loss of life from the Titanic disaster has provoked more outrage than the fact that the ship did not carry enough lifeboats for all her passengers and crew. This is partially due to the fact that the law, dating from 1894, required a minimum of 16 lifeboats for ships of over 10,000 tons. This law had been established when the largest ship afloat was RMS Lucania. Since then the size of ships had increased rapidly, meaning that Titanic was legally required to carry only enough lifeboats for less than half of its capacity. Actually, the White Star Line exceeded the regulations by including four more collapsible lifeboats—making room for slightly more than half the capacity.
In the busy North Atlantic sea lanes it was expected that in the event of a serious accident to a ship, help from other vessels would be quickly obtained, and that the lifeboats would be used to ferry passengers and crew from the stricken vessel to its rescuers. Full provision of lifeboats was not considered necessary for this.
It was anticipated during the design of the ship that the British Board of Trade might require an increase in the number of lifeboats at some future date. Therefore lifeboat davits capable of handling up to four boats per pair of davits were designed and installed, to give a total potential capacity of 64 boats[84]. The additional boats were never fitted. It is often alleged that J. Bruce Ismay, the President of White Star, vetoed the installation of these additional boats to maximise the passenger promenade area on the boat deck. Harold Sanderson, Vice President of International Merchantile Marine refuted this allegation during the British Inquiry.[85]
The lack of lifeboats was not the only cause of the tragic loss of lives. After the collision with the iceberg, one hour was taken to evaluate the damage, recognize what was going to happen, inform first class passengers, and lower the first lifeboat. Afterward, the crew worked quite efficiently, taking a total of 80 minutes to lower all 16 lifeboats. Since the crew was divided into two teams, one on each side of the ship, an average of 10 minutes of work was necessary for a team to fill a lifeboat with passengers and lower it.
Yet another factor in the high death toll that related to the lifeboats was the reluctance of the passengers to board them. They were, after all, on a ship deemed to be "unsinkable". Because of this, some lifeboats were launched with far less than capacity, the most notable being Lifeboat #1, with a capacity of 65, launched with only 12 people aboard.
Alternative theories
A number of alternative theories diverging from the standard explanation for the Titanic's demise have been brought forth since shortly after the sinking. Some of these include a coal fire aboard ship,[86] or the Titanic hitting pack ice rather than an iceberg.[87][88] In the realm of the supernatural, it has been proposed that the Titanic sank due to a mummy's curse.[89]
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