Bushnell's Turtle 1776 - David Bushnell builds the one-man human powered Turtle submarine. The Colonial Army attempted to sink the British warship HMS Eagle with the Turtle, although unsuccessfully. The Turtle is the first submarine to dive, surface and be used in Naval combat. David Bushnell’s Turtle, the first American submarine. Built in 1775, its intended purpose was to break the British naval blockade of New York harbor during the American Revolution. With slight positive buoyancy, Turtle normally floated with approximately six inches of exposed surface. Turtle was powered by a hand-driven propeller. The operator would submerge under the target, and using a screw projecting from the top of Turtle, he would attach a clock-detonated explosive charge. This 1875 drawing by Lt. Francis Barber is the most familiar rendering of Turtle. However, it contains several errors, including internal ballast tanks and helical screw propellers. (Hi-Rez)