Steam-powered vessels include steamboats and steamships. Smaller steamboats were developed first. They were replaced by larger steamships which were often ocean-going. Steamships required a change in propulsion technology from sail to paddlewheel to screw to steam turbines. The latter innovation changed the design of vessels to one that could move faster through the water. Engine propulsion changed to Steam turbine in the early 20th century. In the latter part of the 20th century, these, in turn, were replaced by gas turbines.