|Fifth Scorpene class (Kalvari class) submarine INS Vagir during launching (Picture source: Indian Navy)|Indian Mazagon Dock Shipbuilders is set to deliver India’s fifth Scorpene class (Kalvari class) submarine by the end of the year and a sixth early next year. The Kalvari class is a class of diesel-electric attack submarines based on the Scorpène-class submarine being built for the Indian Navy. The class and submarines take their names from the first submarines inducted in the Indian Navy. The submarines are designed by French naval defence and energy company DCNS and are being manufactured by Mazagon Dock Limited in Mumbai.
The Kalvari class is capable of offensive operations across the entire spectrum of naval warfare including anti-surface warfare, anti-submarine warfare, intelligence gathering, mine laying, and area surveillance.
It has a length of 67.5 m (221 ft 5 in), a height of 12.3 m (40 ft 4 in), an overall beam of 6.2 m (20 ft 4 in), and a draught of 5.8 m (19 ft 0 in). It can reach a top speed of 20 knots (37 km/h; 23 mph) when submerged and a maximum speed of 11 knots (20 km/h; 13 mph) when surfaced.
The submarine has a range of 6,500 nautical miles (12,000 km; 7,500 mi) at 8 knots (15 km/h; 9.2 mph) when surfaced. Each ship is powered by four MTU 12V 396 SE84 diesel engines, has 360 battery cells (750 kg, 1,650 lb each), for power, and has a silent Permanently Magnetised Propulsion Motor.
The hull, fin, and hydroplanes are designed for minimum underwater resistance, and all equipment inside the pressure hull is mounted on shock absorbing cradles for enhanced stealth.
Special steel was used in its construction which has high tensile strength, capable of withstanding high yield stress and hydro-static force. Each submarine has 60 km (37 mi) of cabling and 11 km (6.8 mi) of piping. The class displaces 1,615 tonnes (1,589 long tons) when surfaced and 1,775 t (1,747 long tons) when submerged.
This class is equipped with six 533 mm (21 in) torpedo tubes for a combination of 18 heavyweight wire-guided German-made Surface and Underwater Target (SUT) torpedoes and SM39 Exocet anti-ship missiles or 30 mines in place of both.
The class is also fitted with mobile C303/S anti-torpedo decoys for self-defence. The weapon systems and sensors are integrated with Submarine Tactical Integrated Combat System (SUBTICS).
It has a sonar system is capable of Low-Frequency Analysis and Ranging (LOFAR) enabling long-range detection and classification. Each submarine has a complement of 8 officers and 35 sailors.