Titanic was an incredible feat of engineering, and the most well-known ship accident of the 20th Century – but just exactly how was it powered?
The Titanic was powered primarily by steam created by water heated in boilers, using coal-fired furnaces. Over 80% of the power generated was used for propulsion and the rest for generating electricity.
The amount of electricity generated was greater than that of the average urban power station of the day. The owners of the Titanic, the White Star line, had successfully tested the propulsion system on another ship in their fleet, the SS Laurentic.
What follows is a more detailed explanation of the power system.
The Boiler System
There was a total of 29 boilers on the Titanic. Six boiler rooms, interspersed with five coal bins, were situated midships, below the water line.
Twenty-four of the 16-foot boilers were double-headed, in that they were heated at both ends. These provided the steam power for propulsion. The remaining five boilers were heated from one side only.
The 159 furnaces operated day and night, even when the ship was in harbor. They had to be fired up 6 hours ahead of departure, in order for the ship to operate at the required speed.
More than 600 tons of coal was used each day, generating a hundred tons of ash that had to be dumped at sea. More than 4000 tons, which took 24 hours to load, was required for a Transatlantic crossing.
The steam generated was piped to engines to the rear of the ship, in two long pipes.
Two Reciprocating, Triple Expansion (Four Cylinder) Engines
Each pipe delivered steam, at a pressure of 215 psi (pounds per square inch), to the first cylinder or expansion chamber of a reciprocating steam engine. The engine’s pistons were powered on the way up and the way down.
The steam was then released into a second cylinder at 78 psi. As the pressure decreases, the volume of steam increases. Two cylinders were required in the third phase of the engine when the pressure dropped to 24 psi.
Each of the four-cylinder steam engines had an output of 15000 horse power and, via a long shaft, drove one of the outside propellors. The propellors were 23.5 feet in diameter and weighed 38 tons each.
The Turbine Engine
The steam leaving the two reciprocating engines entered a manifold at 9 psi. This powered a 16000 horse power turbine engine attached to the smaller central propellor.
This propellor was 17 feet in diameter and weighed 22 tons. Unlike the two outer propellors, it was only used in open seas and was not capable of going into reverse.
The steam entered the condenser at 1 psi, where it was cooled to its liquid form, using sea water, and recycled back into the boiler system.
Four steam driven generators, each delivered 400 kilowatts of electrical power to the rest of the ship. Two additional 30-kilowatt generators were available for use in emergencies.
These generators were situated aft of the turbine engine enabling the lights on the ship to remain on while it was sinking.
Two additional engines were needed to move the rudder which was almost 80 feet high, weighed over 100 tons and was impossible to operate manually.
These engines were powered directly by the boilers. Only one was used at a time, with the other being kept in reserve as a backup.
Three of the Titanic’s four funnels, or smoke stacks, were used as exhausts for removing soot and smoke from the furnaces.
A fourth funnel was used as a vent for the lower decks, and the engine and turbine rooms. It also served as a chimney for the fireplaces in the living quarters and an extractor for the stoves in the galleys.
In addition, the fourth funnel added prestige and an aesthetic element to the overall design. It gave the impression that the ship was more powerful than it was.
It also provided a lookout, or crow’s nest, for the crew who did not have access to the upper decks.
Titanic’s First and Last Voyage
At the time that it was built, the Titanic was the world’s largest and most expensive commercial liner. First class facilities were designed to make its wealthy passengers forget that they were at sea.
Sadly, much of the ship’s worth was not tested, as it sank on its maiden voyage, within five days of setting sail from Southampton, England.
In the dark, early hours of 15 April 1912, more than 1500 passengers and crew, more than two-thirds of those aboard, lost their lives in the icy waters of the North Atlantic Sea.