SubmarinesA submarine is a ship that can travel under water. Military submarines are used in wars toattack enemyvessels. They are very large, up to 60 meters long.Scientistsuse submarines toexplore the oceans and get information about plant and sea life deep under thesurface.Parts of a submarineSubmarines are oftenshapedlike acigar, so that they can travel quickly under the oceansurface. A submarines outer part is thehull. It is made out of strongsteel; otherwise it would becrushedby thepressureof the water. Tanks are in the hull. When a submarinedivesthese tanks are filled with water and the sub becomes heavier. If a sub wants to come up to thesurfacethe water is pumped out of the tanks andreplacedby air, which makes the submarine lighter.The sail is the tall thin tower at the top of a submarine. It is the commandbridgeof a sub with all the instruments,antennaeandperiscopeswhich allow the captain or other crew members to see what happens on the surface.

How a submarine worksModern submarines spend most of theirsailingtime under water. They candiveto adepthof about 400 meters. Todays submarines have anuclear reactoron board. It produces the heat that is needed to makesteam. Steam turns theturbinesand propellers that make the ship move forward.Earlier submarines werepropelledby diesel engines. They ran when the submarine was on the surface .Under water they used batteries tooperate. Such subs were not able to stay under water for a very long time and had to come up forair suppliesevery few hours. Nuclear submarines do not need air. Special machines turn salt water into drinking water andextractoxygento make air. They can stay under water for months withoutsurfacing.

Life on a submarineSubmarines usually travel for about two or three months before they come back to their homeport.Sailorson board modern submarines canenjoy manyluxuriesin their free time. There are cinemas, librariesgame rooms, satellite TV and other facilitiesto help them spend their time when they areoff duty.When a submarine reaches its homeportit is checked andrepairsare made if necessary. The crewleaves the sub and a new crewreplacesit.HistoryThe first submarine was built in 1620 by a Dutchscientist. He covered arow boatwithhidesand could travel in water that was 4 meters deep.In the 1800s many types of submarines were built. They werepoweredby gas,steamand batteries. By 1900 most submarines had diesel engines and electric motors that worked with battery power.In World War I Germany started using submarineseffectivelyas warships. In May 1915 a German sub sank the British passenger ship Lusitania, killing over 1,200 passengers.InWorld War IIGerman U-boats sank thousands ofAlliedships. They travelled in groups called wolf packs. American submarinesoperatedmainly in the Pacific Ocean where they attacked anddestroyed apanesevessels.

Diesel engines in a submarineIn 1954 the firstnuclear-poweredsubmarine, the Nautilus, was built by the Americans. It was the fastest sub in the world and could stay under water for a long time. In 1958 the Nautilus was the first submarine tosailunder the ice of the North Pole.In thedecadesthat followed nuclear submarines carriedmissilesand nuclearweaponsthat could hittargetsthousands of kilometres away. This made submarines a very dangerousweaponof war.Today the USA, Russia and China have the biggest submarinefleets.OnlineArticles in Easy, Understandable English for Learners Home Search A-Z Topic Index Print Topic