The Scorpene-class Diesel-Electric Submarines P75-I / air-independent propulsion (AIP) submarines are based on the Scorpene-class submarines, which were designed by a French naval shipbuilding firm DCNS in partnership with Spanish shipbuilding firm Navantia.
The Indian Navy’s Project 75I (P75I) Scorpene submarine development for six latest-generation attack boats is expected to be completed by 2022.
About Project 75-I project
This Project is part of India’s 30-year submarine construction plan that ends in 2030.
Six Scorpene-class submarines are being built under Project-75 by Mazagon Dock Limited (MDL), Mumbai, under technology transfer from the Naval Group of France. It is apart of a $3.75 billion deal signed in October of 2005.
Six Submarines Under Project 75-I
Date of Launch
Date of Commission
27 Oct 2015
14 Dec 2017
12 Jan 2017
28 Sep 2019
31 Jan 2018
10 Mar 2021
06 May 2019
12 Nov 2020
Comparison with other Naval forces
The naval force of Pakistan is estimated to have ten submarines, of which five French-origin Agosta 90B class (Khalid class) conventional vessels are fully operational.
Pakistan Government has signed a deal for eight conventional submarines with China after it failed to get the vessels from France and Germany due to price and technology transfer issues.
According to some media reports, China’s People’s Liberation Army Navy (PLAN) has four Jin-class SSBNs and nine SSNs.
Some reports also suggest China has a fleet of 40-plus diesel-electric submarines beset by maintenance issues.
This Submarine project will not only be a significant increase in the Indian Navy’s firepower but also ensure the stronghold of India in the Indian Ocean region.
When the submarine operates underwater, the batteries onboard power the propeller and other electrical systems onboard the submarine.
The batteries run out of charge within 4-5 days, and the sub needs to recharge them. This is done by snorkelling, which exposes them to detection by enemy radars and makes them an easy target for hostile anti-submarine assets.
Although modern snorkels are coated with radar-absorbing paint and stealthy, they are still detectable by high-resolution radars.
There are also sensors called diesel sniffers, which can easily detect the exhaust emissions of the submarines diesel generators while snorkelling.
A submarine that needs to surface every day loses its ability of surprise and increases its vulnerability to hostile anti-submarine assets.
AIP systems allow conventional submarines to recharge their batteries without surfacing for air, which enables them to remain underwater for extend periods and not expose themselves to detection.
AIP is a technology based on the combustion of stored oxygen and ethanol to increase the battery-powered propulsion system.
Significance of AIP:
Air-Independent Propulsion significantly improves the stealth of the Submarine because it enables a sub to generate electricity for services, battery charging, and propulsion while completely submerged underwater.
AIP systems also generate electricity, powering a submarine also generate oxygen, lighting, and amenities for the crew.