2. HOW DO SUBMARINERS SEE, HEAR AND SPEAK UNDER WATER?
On or near the surface, submariners 'see' through a periscope mast raised through the fin above the hull from within the submarine's Control Room. In the very latest submarines, the extendable periscopes will be largely superseded by an electronic mast that uses a camera and displays the picture on a monitor. The optronics masts have a closed circuit television (CCTV) camera to use by day or thermal imaging (heat seeking) camera for use at night or in bad visibility.
Submarines cannot see underwater and so use sound energy to detect obstacles and objects. When under the water the submarine can emit SONAR (SOund Navigation And Ranging) sound waves through the water (known as 'pinging'). The sound wave or sonar ping echo is bounced back to the submarine if it detects another vessel or obstacle.
The strength of the returned signal or sound provides an indication of the range (distance) between the submarine and the other vessel (ship or submarine) or obstacle.
Modern submarines have excellent radio and satellite reception and communications systems and underwater telephones. When sending out sound waves by sonar, a submarine could be detected by another ship or submarine. When wishing to remain undetected, a submarine will listen for and hear sounds underwater through hydrophones (underwater microphones).
