The first known treatise on submarines was written in 1578. Published by William Bourne in his Inventions or Devices, the document describes a ship with two hulls, the outer made of wood. While no record exists concerning its manufacture, the ship, according to Bourne, could be submerged or raised by taking in or expelling water from between the double hulls. The first known submarine was built by Dutch inventor Cornelius Drebbel, and consisted of greased leather over a wooden framework. It was propelled either on or beneath the surface by eight oars sealed through the sides with leather flaps. During a demonstration for James I in 1620, this vessel was successfully piloted just under the surface of the Thames River. It was unable, however, to make deep descents.
During the American Revolution, David Bushnell built a one-man submarine called the Turtle. It resembled an egg squashed thin with a height of 6 ft (2 m), and had two hand-cranked screw propellers, a hand-operated control lever connected to the rudder, foot-operated pumps to let water in or send it out (to submerge or surface), and a crudely-lit control panel. As if it was not dangerous enough simply to get in the water sealed inside this device, the Turtle also had a large explosive attached to it in the hopes the operator could maneuver under an enemy ship, screw the explosive into the ship's hull, and depart before the explosive's timing device discharged it. Unfortunately, the Turtle failed to sink any ship. On its only test mission, the Turtle was assigned the task of bombing the British HMS Eagle in New York, but its pilot was unable to screw the explosive into the Eagle's copper hull.
Others, such as English carpenters Symons and Day, included ballast systems on their submarines to permit descents. Day's submarine resembled a sloop, and had two large bags of stones hanging from its bottom to serve as ballast. Day would sink, then jettison the rocks to return to the surface. After two successful tests, Day confidently decided he would test his vessel off Plymouth Sound, a site with a depth of 900 ft (274 m). Apparently his ship was crushed by high water pressure, for when he and his crew descended, a crowd of onlookers waited in vain for his return. Day and his crew had become the first victims of a submarine mishap.
Perhaps the most successful early submarine was designed by Robert Fulton. In an age of naval battles, Fulton, who detested war, felt that a device capable of neutralizing the effectiveness of warships would end war altogether. While living in France in 1767, he outlined plans to build a sub called the Nautilus and unsuccessfully attempted to interest the French government in his idea. By 1801, however, he had managed to complete a submarine on his own. A 21 ft (6 m) vessel with a twobladed propeller, the Nautilus performed well in tests, even sinking a ship with an explosive charge. But he was once again rejected by the French government, so he moved to England, hoping for a better reception there.
It soon became clear that the English did not want his submarine either. In fact, Fulton had failed not because his vessel did not work, but because major naval powers feared his vessel and did not want to participate in developing a weapon that could negate their military strength. Fulton went on to produce his famous steamboats in the United States.
After the American Civil War, designers, spurred on by the invention of the self-propelled torpedo in 1866, increasingly sought alternatives to human-powered propulsion for submarines. Several systems proved unsuitable—steam engines made the craft unbearably hot and an electric battery could not be recharged at sea. In the late 1890s, however, Irish-born American John Holland solved the problem with the use of a new power source, the gasoline engine. Because it needed oxygen, the gasoline engine could not be used while a submarine was underwater, but on the surface it could not only provide propulsion but also charge the batteries used while submerged. Holland's vessels incorporated many of the features we associate with modern subs: a powerful engine, advanced control and balancing systems, and a circular-shaped hull to withstand pressure. The United States Navy accepted his submarine, the Holland, in 1900.
Around this time, two other improvements were introduced. Simon Lake (1866-1945), who also built an early gasoline-powered submarine, created the first periscope specifically for submarines: it provided a magnified view and a wide angle of vision. In the 1890s Rudolf Diesel invented an engine that was fired by compression rather than an electric spark. The diesel engine was more economical than the gasoline engine and its fumes were much less toxic and volatile. This new engine became the mainstay of all submarines until nuclear power was introduced as a means of propulsion in the 1950s.
Germany made good use of diesel propulsion. Unlike Britain's small, coastal subs, Germany's vessels, displacing up to 3,200 tons, were capable of crossing the Atlantic. Their U-boat (short for unterseeboot) sent more than 11 million tons of Allied shipping to the bottom and, in the process, created a new, terrifying type of warfare.
In World War II submarines played an even larger role in Germany's repeated attacks on Allied shipping, eventually destroying 14 million tons of shipping. Meanwhile, American submarines crippled the Japanese by sinking nearly 1,400 merchant and naval ships. The greatest improvement came through the development of the snorkel, a set of two fixed air pipes that projected from the sub's topside. One tube brought fresh air into the vessel, and the other vented engine exhaust fumes. Now a sub could stay hidden below the surface when running on its diesel engine and recharging its batteries.
The greatest advance in submarine technology was the advent of nuclear power. With the encouragement of United States Navy Captain Hyman Rickover, American inventors Ross Gunn and Phillip Abelson designed the U.S.S. Nautilus, the first nuclear-powered submarine. Launched in 1955, the Nautilus carried a reactor in which controlled nuclear fission provided the heat that converted water into steam for turbines. With this new power source, the submarine could remain under water indefinitely and cruise at top speed for any length of time required.
For a submarine able to remain under water for longer distances at higher speeds, a needle-like shape proved inefficient. The Davis Taylor Model Basin in the United States developed a new teardrop design, first tested on its Albacore submarine. Vessels with this improved shape easily drove through the water at speeds of 35-40 knots per hour. The United States Navy later adopted the Albacore's shape for its submarines.
Submarines have also benefited from advances in navigation equipment. Inertial navigation systems, relying on gyroscopes, now fix their position with extreme accuracy. The U.S.S. Skate used this system to navigate under the polar ice cap at the North Pole in 1959.
See also Internal combustion engine.