The biggest submarines are nuclear-powered naval submarines. The biggest of all are Russian Typhoon Submarines. They’re 171metres long (as long as two football pitches) and weigh 26,500 tonnes. They can stay under water for months on end and sail around the world without refueling.
What was a U-boat?
U-boats were German submarines used in World War One and World War two. U-boat is short for underwater boat. U-boats sank thousands of ships. They crept up silently, hidden under the water, and fired missiles called torpedoes. The torpedoes zoomed through the water and exploded when they hit the ships.
Amazing! The first working submarine looked like a wooden barrel. It was built in 1776 and was called Turtle. The operator sat inside and pedalled to make its propellers turn. Turtle was designed to attack ships by diving under them and fixing a bomb to their hulls. But it was never successful.
Is it true? Submarines use sound to see.
Yes. A submarine’s sonar machine makes beeps of sound that spread out through the water. If the sound hits an object in the water, it bounces back to the submarine and is picked up by the sonar machine. The machine works out how big the object is and how far away it is.
What is a periscope?
Submarine crews use their periscopes to see ships on the surface above them when submarines are submerged. The top of the periscope sticks just above the surface. It works using several lenses and prisms (triangular pieces of glass).
Picture Credit : Google