An inboard motor is a marine propulsion system for boats. As opposed to an outboard motor where an engine is mounted outside the hull of the craft, an inboard motor is an engine enclosed within the hull of the boat, usually connected to a propulsion screw by a driveshaft. In international shipping the marine diesel engines are the largest most powerful engines ever produced. History The first marine craft to utilize inboard motors were steam engines going back to 1805 and the Clermont and the Charlotte Dundas. Harbour tugs, and small steam launches had inboard steam engines. In the 1880s the naphtha engine made its appearance and a few boat engines appeared. Such engines had low power and high fuel consumption. The gasoline (petrol) engine pioneer Gottlieb Daimler and Maybach built a four-cycle boat engine and tested it in 1887 on the Neckar River. Sintz in America built several commercially available engines from 1893. Sizes Inboard motors may be of several types, suitable for the size of craft they are fitted to. Boats can use one cylinder to v12 engines...