The Under-Water Craft (Submarine)
A submarine (or simply sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term most commonly refers to a large, crewed vessel. The noun submarine evolved as a shortened form of submarine boat; by naval tradition submarines are usually referred to as "boats" rather than as "ships", regardless of their size (boat is usually reserved for seagoing vessels of relatively small size).
When were they used first?
Although experimental submarines had been built before, submarine design took off during the 19th century, and they were adopted by several navies. Submarines were first widely used during world war I (1914–1918), and now figure in many navies large and small. Military uses include attacking enemy surface ships (merchant and military), attacking other submarines, protection, blockade running, ballistic missile submarines as part of a nuclear strike force, reconnaissance, conventional land attack (for example using a cruise missile), and covert insertion of special forces. Civilian uses for submarines include marine science, salvage, exploration and facility inspection and maintenance. Submarines can also be modified to perform more specialized functions such as search-and-rescue missions or undersea cable repair. Submarines are also used in tourism, and for undersea archaeology.
Inception & Invention
1620: Englishman Cornelis Drebble (1572–1633) builds the first submarine by waterproofing a wooden, egg-shaped boat with leather and coating the whole thing in wax. Scientists are uncertain whether Drebble's boat ever set sail.
1776: During the US revolution, David Bushnell (1742–1824) builds a hand-powered one-person submarine called the Turtle to help attack British warships.
1800: American steam engineer Robert Fulton (1765–1815) designs a convertible ship with folding-down sails that can turn itself into a submarine for traveling underwater.
1897: American inventor Simon Lake (1866–1945) launches the Argonaut, the first submarine to operate in the open sea.
1900: The US Navy launches its first ever submarine, the USS Holland, named for its Irish-American inventor John Holland (1840–1914). Although Holland had offered submarines to the Navy for years beforehand, it had originally shown no interest.
1914–18: During World War I, the German navy operates a fleet of highly effective military submarines called U-boats (short for Unterseeboot, which means underwater ship). In the 1930s, the Germans start using snorkel tubes (invented by a Dutch engineer) to supply air to their U-boat's diesel-electric engines, giving them greater range and effectiveness.
1955: The US Navy launches the USS Nautilus, the first nuclear-powered submarine.
1968: The Soviet Union (Russia and its former allies) launches K-162, the first submarine with a titanium hull and the world's fastest.
1969: The Soviets launch the first of their sleek, fast, titanium-hulled Alfa-class nuclear submarines.
1990s: Nuclear submarines made redundant by the end of the Cold War are used for oceanographic and climate research in the Arctic in a project named Science Ice Exchange (SCICEX).
How a Submarine Works?
A submarine or a ship can float because the weight of water that it displaces is equal to the weight of the ship. This displacement of water creates an upward force called the buoyant force and acts opposite to gravity, which would pull the ship down. Unlike a ship, a submarine can control its buoyancy, thus allowing it to sink and surface at will.
To control its buoyancy, the submarine has ballast tanks and auxiliary, or trim tanks, that can be alternately filled with water or air (see animation below). When the submarine is on the surface, the ballast tanks are filled with air and the submarine's overall density is less than that of the surrounding water. As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine until its overall density is greater than the surrounding water and the submarine begins to sink (negative buoyancy). A supply of compressed air is maintained aboard the submarine in air flasks for life support and for use with the ballast tanks. In addition, the submarine has movable sets of short "wings" called hydroplanes on the stern (back) that help to control the angle of the dive. The hydroplanes are angled so that water moves over the stern, which forces the stern upward; therefore, the submarine is angled downward.
A Submariner’s State of Mind
Submarine service is a stealthy and secretive business by nature and necessity. The course of executing missions routinely involves venturing unseen into the unknown. Conducting classified work that can’t be discussed outside the world in which one operates. And taking on responsibilities that most can’t fathom.
If you want to make it here, you need to have the smarts to do highly technical work. You need to be versatile enough to do your job and at the same time be prepared to do things like fight fires and control flooding. And you need to have an unwavering team mentality.