Naval History and Heritage Command, Photographic Section, UM-23.
At present, 43 nations have over 600 submarines
TNN | Aug 19, 2013, 06.03 AM IST
The INS Sindhurakshak tragedy has brought the focus on the mysterious world of submarines. Here are some interesting submarine facts.
When was submarine first used in war?
By early 18th century, many inventors made several designs of naval vessels that could travel on the surface as well as beneath water. The American Revolution was the first war that witnessed military deployment of such boats. Submarines were also used during the American civil war. Submarines equipped with torpedo became a major factor during the First and the Second World War. According to US navy at present there are 43 countries operating over 600 submarines.
How does a submarine submerge?
One of the most important features of a submarine’s design is the ballast tanks. These tanks could be alternatively filled with water or air depending on the requirement, whether the vessel wants to float on water’s surface or travel underwater. The tanks are filled with air when the submarine is at the surface. To submerge the air is released and the tanks are filled with sea water which makes the vessel heavier.
Submarines maintain a stock compressed air while travelling underwater. This air is used for life support and for filling the ballast tank.
How does a submarine propel?
Most of the today’s diesel submarines work like a hybrid vehicle. A typical diesel submarine has two diesel engines. One engine is used to propel the vehicle when it is on surface while the other is used to charge its batteries. These vehicles can only go underwater after fully charging their batteries. After going underwater they are propelled by battery-powered electric motors. Because of the battery powered propulsion the diesel submarine can stay underwater for a limited period.
A nuclear powered submarine is not based on combustion engine. Unlike diesel subs, a nuclear sub doesn’t need air to burn it fuel and hence it can remain underwater for a much longer period.
How is the underwater navigation done?
Typically, submarines don’t have windows and hence the crew could see outside underwater. When a submarine is near surface then it uses periscope to have the outside vision. Most of the submarine travel much deeper than the periscope depth and the navigation is done with the help of computers. Like any other conventional ship, a submarine navigator is also dependent on regular ocean navigation chart.
The submarine uses Sonar (Sound Navigation and Ranging) to detect target ships.
How is the submarine’s environment controlled to support life?
Modern submarines- nuclear as well as diesel are designed to stay underwater for a significantly longer period. To have a healthy environment for humans a submarine is required to maintain earth like air quality, supply fresh water and maintain suitable temperature. Most of the submarines are equipped with oxygen generator and water purifiers.
These equipments use sea water to generate oxygen as well as produce fresh water. Apart from this the carbon dioxide and moisture is periodically removed to keep the environment healthy.
Department of Defense PIN 25126.