Wednesday, October 24, 2012

Ships and Steam Engines

In the 19th century, reciprocating steam engines were used to replace sails. Today most of the ships and boats use marine diesel engines as their driving power. The introduction of the marine internal combustion engine in 20th century quickly replaced steam engines that consumed a lot of spaces but only produced less power. In addition to more efficient use of rooms, diesel engines give higher power with less fuel consumption compared to steam engines. As a result, ships whose steam engines had been replaced by diesel engines could carry more cargoes and passengers with higher speed. Reciprocating steam engines were popular during 19 century only. In 20th century, they were progressively replaced by steam turbines. The application of steam engines on marine vehicles may become attractive again if the price of conventional fossil fuel rises uncontrollably.
 As a matter of fact, steam engines were more flexible in terms of their fuel needs. Because the combustion is done externally i.e. separated from the working fluid, it could be operated with coal, wood or liquid fuel such as diesel fuel. I remember reading a book entitled The Malay Archipelago by Alfred Russel Wallace. On a chapter about Dorey bay in New Guinea island, he said that a Dutch patrol boat ran out of coal when she arrived in the bay. The coal that the crews were waiting from Ambon had not arrived. So, they went to shore and started cutting trees. Then they loaded her holds with wood. The ship would use it go sail back to Ambon. Unfortunately, the efficiency of steam engines are lower than diesel engines or steam turbines. However, some steam boats still operate as tourist vessels.
Another reason for the abandonment of steam engines application in maritime sector was the air pollution created from the burning of coal. During World War I and II, ships could easily be spotted by their enemies from the smoke that they released into the air. Modern fast patrol boats that are driven by diesel engines have got exhaust pipes below the water line. The hot gas released by main engine could not be detected by heat seeking missiles.
Nowadays a lot of traditional wooden boats still use sails as their driving power whereas steam engines have disappeared from marine application for nearly a century. Hobbyists are still studying the engines and constructing them for their boat. They do it for its application in marine tourism. Many people who still use steam engines that burn wood do so just because they do not want to depend on fossil fuel. by Charles Roring

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