Scorpene-class submarines

The Prime Minister, Shri Narendra Modi, on Thursday dedicated the naval submarine INS Kalvari to the nation, at a function in Mumbai. Congratulating the people of India on this occasion, the Prime Minister described INS Kalvari as a prime example of "Make in India." Kalvari is the first of the indigenous Scorpene-class submarines.

The Scorpène-class submarines are a class of diesel-electric attack submarines jointly developed by the French Direction des Constructions Navales (DCN) and the Spanish company Navantia, and now by DCNS. It features diesel propulsion and an additional air-independent propulsion (AIP).

The submarines, designed by the French naval defence and energy company, are being built in Mumbai as part of Project-75 of the Indian Navy. All six diesel-electric attack submarines will be equipped with an anti-ship missile, which has a proven record in combat, besides other weapon systems. In May this year, the navy successfully test-fired an anti-ship missile from INS Kalvari.

A second Scorpene submarine, INS Khanderi, is also undergoing trials and is likely to be inducted shortly. The Scorpene submarine is designed to operate in all theatres of war, including the tropics. It is capable of handling various missions such as anti-surface warfare (attacking surface ships), anti-submarine warfare (destroying submarines), intelligence gathering, mine-laying and area surveillance.

The Kalvari was built with a special kind of high-tensile steel that is capable of withstanding high yield stress. This feature allows it to withstand pressure exerted by water and hydrostatic force, while diving deeper to enhance stealth. It is also capable of carrying weapons that can be easily reloaded at sea, a report on Hindustan Times said.

The French Module d'Energie Sous-Marine Autonome (MESMA) system is being offered by the French shipyard DCN for the Scorpène-class submarines. It is essentially a modified version of their nuclear propulsion system with heat being generated by ethanol and oxygen. Each MESMA system costs around US$50–60 million.

As installed on the Scorpènes, it requires adding a new 8.3 metres (27 ft), 305 tonne hull section to the submarines, and enables a submarine to operate for more than 21 days under water, depending on variables such as speed. Some of the submarines built for the Indian Navy will have phosphoric acid fuel cell-powered AIP modules designed by the Naval Materials Research Laboratory of the Indian Defence Research and Development Organisation (DRDO).