The reason for this historical material is my desire to give my Sound School students some knowledge about ships and the problems of building them. We learn from what has gone on before our time. This is material for the students’ frames of reference and background information. A math teacher can afford to show students that he is interested in other topics, and the material ties in with the theme of the school.
A. The
Great Eastern
The technological “giant steps” of any historical period determine the topics of scientific research for that period. The Great Eastern was one such giant step. It was a ship “before its time.”
Construction of the
Great Eastern
started in 1854, her launching began in November, 1857, and she finally floated at the end of January, 1858. She was 680 feet long; the next longest ship of her day was 380 feet. Her length was not exceeded until the
Oceanic
in 1899, and her tonnage was not exceeded until the
Lusitania
in 1906. The reason it took three months to launch her was that metal rails were used for the ways and the cradles were iron shod. So much heat was generated by the friction of iron against iron that the cradle shoes and the rails welded themselves together in November at the first attempt. The ship was jacked down the ways an inch at a time after jacks were designed and built.
She was the only vessel ever built that had sails, paddle wheels, and propellers, with the paddle wheels and propellers having their own independent engines. She burned a ton of coal per mile. She had a capacity of 12,000 tons of coal. She was under powered; she had about 2600 horsepower with a top speed of 14.5 knots on a displacement of 27,000 tons. Remember, no one had ever done this before; there were bound to be mistakes and unforeseen problems. All of her problems pointed out the need for even more scientific investigations. Her builders had been successful in their previous ventures building other ships, railroads, and bridges.
One engineer associated with the
Great Eastern
was William Froude. From his experiences grew his life’s work, the study of the powering of ships. Another person to research are J. Scott Russel who designed her and built her in his ship yard. The name that most people associate with the
Great Eastern
is Isambard Kingdom Brunel, the owners’ technical advisor and probably the top engineer of the time. It is a question of historical research as to how much Brunel contributed to the design; it is called “Brunel’s great ship” and its misfortunes are said to have killed him.
One success of the
Great Eastern
was the laying of the transatlantic telegraph cable after the Civil War. To learn more, see the article by Chiles in the Fall 1987 issue of
Invention & Technology
.
Another reference to see is
The Great Iron Ship
by James Dugan. Here you will learn that the
Great Eastern
was launched broadside. She was double hulled to six feet above the water line. In fact, her double hull saved her. On her first voyage to the United States she hit an unchartered rock pinnacle which tore a hole eighty-three feet long and nine feet wide in the outer hull. The rock is still known as the Great Eastern Rock after the ship that found it, the only ship big enough to find it. The hull was repaired by using a cofferdam so the work could be done while the ship was afloat, another feat of engineering.
B.
Turbinia
and Cavitation
In search of more speed, more efficient engines were built and placed in ships. The first turbine powered ship was Sir Charles Parsons’
Turbinia
built in 1894. Parsons had built the first successful turbine to power a dynamo, an electric generator. He had done model tests and had great expectations for the ship, since the turbine was so powerful.
The results were disappointing. The highest speed recorded was less than 20 knots. The problem was cavitation, a phenomenon recognized and named by William Froude. The propellers were spinning at 18,000 rpm, so fast that the water pressure decreased, forming bubbles, a cavity. The power was going into making bubbles instead of pushing the boat.
The remedy was to operate at lower rpm with more turbines and propellers. The original design was one turbine with one shaft of three propellers. The successful design used three turbines which each had a shaft turning three propellers, and it achieved the speed of 34.5 knots in 1897.
More information can be found in the literature listed in the bibliography, especially the LIFE book Ships.
