Editing Steamboat (section)

==Background==
===Limitations of the Newcomen steam engine===
The first steamboat designs used [[Newcomen atmospheric engine|Newcomen steam engines]]. These engines were large, heavy, and produced little power, which resulted in an unfavorable power-to-weight ratio. The heavy weight of the Newcomen engine required a structurally strong boat, and the reciprocating motion of the engine beam required a complicated mechanism to produce propulsion.<ref name="Hunter_1985">{{cite book |title=A History of Industrial Power in the United States, 1730–1930, Vol. 2: Steam Power |last1=Hunter |first1= Louis C.|year=1985 | publisher =University Press of Virginia|location= Charlottesville}}</ref>

===Rotary motion engines===
[[James Watt]]'s design improvements increased the efficiency of the steam engine, improving the power-to-weight ratio, and created an engine capable of rotary motion by using a double-acting cylinder which injected steam at each end of the piston stroke to move the piston back and forth. The rotary steam engine simplified the mechanism required to turn a paddle wheel to propel a boat. Despite the improved efficiency and rotary motion, the power-to-weight ratio of [[Boulton and Watt]] steam engine was still low.<ref name="Hunter_1985"/>

===High-pressure steam engines===
The high-pressure steam engine was the development that made the steamboat practical. It had a high power-to-weight ratio and was fuel efficient. High pressure engines were made possible by improvements in the design of boilers and engine components so that they could withstand internal pressure, although boiler explosions were common due to lack of instrumentation like pressure gauges.<ref name="Hunter_1985"/> Attempts at making high-pressure engines had to wait until the expiration of the [[Boulton and Watt]] patent in 1800. Shortly thereafter high-pressure engines by [[Richard Trevithick]] and [[Oliver Evans]] were introduced.<ref name="Hunter_1985"/>

===Compound or multiple expansion steam engines===
The [[compound steam engine]] became widespread in the late 19th century. Compounding uses exhaust steam from a high pressure cylinder to a lower pressure cylinder and greatly improves efficiency. With compound engines it was possible for trans ocean steamers to carry less coal than freight.<ref name="Hunter_1985"/> Compound steam engine powered ships enabled a great increase in international trade.<ref>{{cite book 
|title=Recent Economic Changes and Their Effect on Production and Distribution of Wealth and Well-Being of Society |last=Wells |first=David A|year=1890 |publisher= D. Appleton and Co.|location= New York|isbn= 0-543-72474-3 |url= https://archive.org/details/recenteconomicc01wellgoog }}</ref>

===Steam turbines===
The most efficient steam engine used for [[marine propulsion]] is the [[steam turbine]]. It was developed near the end of the 19th century and was used throughout the 20th century.<ref name="Hunter_1985"/>