Editing Steamboat (section)

===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"/>