Today, the most feared fighting ships are not surface ships but nuclear submarines.  These craft can remain undetected in any of the Earth's oceans, and can carry enough nuclear missiles to devastate more than a hundred cities.

  Submarines submerge (sink beneath the water) by flooding ballast tanks with water, and surface by emptying them using compressed air.  Like ordinary ships, they use a propeller for propulsion.  The propeller is driven in conventional submarines by a diesel engine on the surface, and by an electric motor underwater.  Nuclear submarines are driven by steam turbines using nuclear energy.

A submarine is steered through the water by means of a vertical rudder and horizontal fins, called diving planes or hydroplanes.  There is one set of planes in the cross-shaped "tail" at the stern, and one on each side near the bow or on the projecting tower, or sail.  The sail acts as a navigation bridge on the surface.  It also houses one or more periscopes and a snorkel tube.  The periscopes enable the crew to see above the surface of the water while remaining submerged.  

  Nuclear-powered submarines are big.  Submarines owned by the Soviet Union's Typhoon class are 170 m (560 ft.) long.  The submarine craft used by civilians, called submersibles, are much smaller.  They are often used for ocean research and for supporting offshore oil production.  


Answer the questions below


1. Nuclear submarines are driven by

an electric motor.

a propeller.

steam turbines.


2. A submarine is steered though the water by diving planes also called .


3. A enables people in submarines to see above the surface of the water while still submerged.


4. To sink beneath the surface of the water is to .


5. The projecting tower or sail of a submarine acts as a


navigation bridge.



6. Submarines used by civilians are called .

7. A submarine surfaces by emptying the ballast using compressed .
8. A conventional submarine is driven by a diesel engine on the surface and an electric underwater.
9. The large Typhoon class of submarines is owned by the
United States.

Soviet Union.


10. Civilian submarines are used for
pleasure trips.

ocean research and offshore oil production.

nuclear war.

11. Nuclear submarines carry enough nuclear to devastate more than a hundred cities.



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