Project 75i- India

Project 75 is a submarine construction project for the Indian Navy.

It was initiated to acquire 6- Scorpene-class submarines featuring next generation Air Independent Propulsion (AIP) systems, with the help of Transfer of Technology (ToT) from France. The project was completed in 2025, and the six submarines, also known as the Kalvari class, have been commissioned.

Project 75 India is an advancement of Project 75, focusing on improved design and technology. AIP technology in Project 75I aims to enable submarines to stay submerged for up to two weeks. Project 75I submarines might be larger compared to those in Project 75.

Now, discussing the stealth features:-

1. They have the same advanced sound absorption techniques, low radiated noise levels, tube-launched anti-ship missiles, long-range guided torpedoes, sonars, and sensor suites as the 75 submarines.

2.  Diesel-electric assault Submarines operating under Project 75 must surface every 48 hours to refuel their diesel generators, which run on air oxygen to charge the batteries.

 However, submarines equipped with AIP technology will be able to stay below for up to two weeks thanks to fuel cells.

 3. Indigenization: At least 45% of the first submarine must be indigenous, and by the sixth, the percentage must reach 60%.

The project was initiated in 1997 and all 6 submarines have been commissioned; the above image is a mind map of the names of those submarines with their induction years.

4.  MSME Development: In addition to supporting the core submarine building business, the project would help the manufacturing sector particularly for MSMEs; by enabling them to produce related spare parts, systems, and equipment.

• A Point to be noticed:

-Conventional submarines need to surface every 48 hours to charge their batteries, because the generator that recharges them is powered by an internal-combustion engine that requires air. This poses a significant risk of their detection.

-Air Independent Propulsion (AIP) system allows submarines to remain submerged for longer durations (up to 15 days) without the need to surface. This significantly enhances their operational endurance and stealth capabilities.

The Challenges with Project 75i

Challenge	Impact
Delays	Push contract and delivery timelines into 2030s, delaying fleet-ready subs
Structural inefficiencies	Capacity constraints + rigid policies slow procurement and building rates
Submarine shortages	Operational fleet halved; urgent strategic gaps persist
Exiting Collaborators	Reliance on a single bidder with still-to-be-proven AIP tech

In conclusion, Project 75(I) is critical to India's naval capability and self-reliance in defense. Addressing the problems associated with cost, knowledge transfer, and timely execution is imperative for the project's success and the upgrading of the Indian Navy's submarine fleet.

-A Blog by Jitisha S Hiremath