The concept of an underwater boat comes from the distant past. The ancient ‘underwater boat’, then called ‘Submersibles’, and now the ‘Submarines’ of the present time, are a sort of invisible power of the naval defense forces across the globe. “Submarine” means “under the sea”. Submarine evolved as a shortened form of submarine boat. These water crafts are capable of independent operation underwater. It has the ability to dive in deep depths and then sneak attack on the enemy without their knowledge. They are the most lethal arsenal of the navy. The might of countries navy is also determined by the number of submarines it has in its fleet. Developed and designed in the early 19th century during the First World War, these underwater war machines were adopted by the navies of several countries.
Now the submarines have a very vital role to play in many large navies. The military usage includes attacking enemy ships, submarines, aircraft as part of a nuclear strike force, conventional land attack, and secret insertion of Special Forces. Civilian uses for submarines include exploration and facility assessment/maintenance, marine science, rescue, etc. Submarines can also be tailored to perform more specific functions such as search-and-rescue missions or undersea cable repair. Submarines are also used for undersea archaeology and in tourism.
Submarines are of a cylindrical body with hemispherical or conical ends and have a vertical structure, which accommodates communications and sensing devices and periscopes as well. There is a propeller at the rear and various hydrodynamic control fins. They have an inner and outer steel shell, called a hull and the area in between the two hulls which is called the ballast tank can be filled with either air or water. When the submarine is on the surface, these ballast tanks are filled with air and the submarine’s overall density becomes less than that of the adjoining water. These ballast tanks are open at the bottom. To dive, the submarine operator opens up valves at the top and lets air out. Seawater rushes in to fill the space that was taken up by air. This changes the ship’s density. Thus, submarines change the amount of water and air in their ballast tanks to decrease buoyancy for submerging or increase it for surfacing.
Today, various studies are resulting in the development of the submarines to make them a powerful part of the navy and the country’s defence system. Technology plays a huge part in it. According to a market report, the Global Submarine market is expected to rise at a CAGR of 3.27 percent over the period 2013-2018. One of the main factors contributing to this market growth is the increased focus and spending on Research & Development. Also the leading vendors in the global Submarine market have stepped in to the developing countries as the developing nations too wish to be self-sufficient in terms of their defence needs. Nevertheless, the cut back in defense budgets across the world can pose a challenge to the growth of this market.