INS Karanj | 06 Feb 2020

The third Scorpene submarine, Karanj, will be delivered to the Indian Navy by December 2020.

INS Karanj is a part of Project-75 and was launched in January 2018. It is currently in advanced stages of sea trials.

It is a programme by the Indian Navy that entails building six Scorpene-Class attack submarines.
The programme has been undertaken with transfer of technology from French company Naval Group (formerly known as DCNS) at the Mazagon Dock Limited (MDL).
The submarines in the P75 Scorpene-Class are powered by the conventional diesel-electric propulsion system.
The first Scorpene submarine, Kalvari, was commissioned in 2017 and it would go for a normal refit after six years in 2023, during which time the Air-Independent Propulsion (AIP) would be installed.
- AIP technology is being developed by the Defence Research and Development Organisation (DRDO) to provide submarines long-range and extended endurance capabilities undersea.
Second Scorpene Khanderi was inducted in September 2019.
The remaining submarines (Vela, Vagir, and Vagsheer) in the series are in advanced stages of manufacturing and trials.

Air-Independent Propulsion

Conventional submarines use a diesel-electric engine, and must surface for oxygen required for fuel combustion. If fitted with an Air Independent Propulsion (AIP) system, the submarine needs to take in oxygen less frequently.
While many naval powers, including India, have acquired nuclear-powered submarines for deep-sea operations, conventional diesel-electric variants are considered useful for coastal defence. The latter are optimised for stealth, and their weapons and sensors provide for effective operations close to the shore.
Diesel-electric submarines require them to come to the surface frequently to charge their batteries, their underwater endurance time is less. ‘Air-independent’ propulsion technology helps to make the diesel generator less dependent on surface air.