Inboard motor

[1] The first marine craft to utilize inboard motors were steam engines going back to 1805 and the Clermont and the Charlotte Dundas.

For pleasure craft, such as sailboats and speedboats, diesel, gasoline and electric[3] engines are used.

The advent of the stern drive propulsion leg improved design so that auto engines could easily power boats.

For larger craft, including ships, where outboard propulsion would in any case not be suitable, the propulsion system may include many types, such as diesel, gas turbine, or even fossil-fuel or nuclear-generated steam.

Other engines, notably small single and twin cylinder diesels specifically designed for marine use, use raw seawater for cooling and zinc sacrificial anodes are employed to protect the internal metal castings.