Nicholas Roosevelt (inventor) 74-gun ships. In 1797, with Robert R. Livingston and John Stevens, he agreed to build a boat on joint account, for which the engines were to be constructed by Roosevelt, and the propelling agency was to be that planned by Livingston. The experiment failed, the speed attained being only equivalent to about in still water. On September 6, 1798, Roosevelt described and earnestly recommended to Livingston a vertical wheel, which is the first practical suggestion of the combination that made steam navigation a commercial success, although four years later Robert Fulton believed that chains and floats were alone to be
Naval tactics in the Age of Steam had important tactical implications. The electric motors were far less powerful than the diesel engines and had a short battery life. When submerged, most submarines were capable of about 10 knots, little more than the slowest merchantman. So a submerged submarine was not only much slower than when on the surface, but also unable to proceed at its maximum submerged speed for any length of time. Submarines of the Second World War were more submersibles than true submarines. Under Admiral Karl Dönitz the U-boats further developed the tactics of surface night attacks that had first been used in the First