What is Project-75I?

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What is Project-75I? Blog Image


Spanish submarine manufacturer Navantia and India’s Larsen and Toubro (L&T) recently concluded a Teaming Agreement, to jointly bid for theProject-75I.

About Project-75I:


  • Under this, the Indian Navy will procure six advanced conventional submarines processed through the Strategic Partnership (SP) model.
  • These will be diesel-electric submarines, having advanced Air-independent propulsion (AIP) systems.
  • Project 75I requires an Indian bidder to tie up with a foreign collaborator and build six conventional submarines equipped with AIP systems.
  • The first submarine must have a minimum of 45% indigenisation, with the indigenous content going up to 60% in the sixth.


What are the types of Submarines?

  • Conventional or Diesel-electric submarine: They need atmospheric oxygen to run the diesel generator which in turn charges the batteries.
  • Nuclear Submarine: It is a submarine powered by a nuclear reactor, but not necessarily nuclear-armed. They have considerable performance advantages over conventional submarines.


What is an Air-independent propulsion (AIP) System?

  • With the emergence of submarines, there was a problem finding satisfactory forms of propulsion underwater.
  • AIP is mostly implemented as an auxiliary source, with the traditional diesel engine handling surface propulsion.
  • Most of these systems generate electricity, which in turn drives an electric motor for propulsion or recharges the boat’s batteries.
  • A typical conventional power plant provides 3 megawatts maximum, and an AIP source around 10 percent of that. A nuclear submarine’s propulsion plant is much greater than 20 megawatts.
  • Key features of the AIP system:
    • It allows the submarines to stay for longer hours in water. The submarines need to come to the surface of the water to charge their batteries. This is reduced by the AIP System.
    • It decreases the noise levels made by the submarines. This makes it hard to detect the submarines.
  • Types of AIP: Open-cycle systems, Closed-cycle diesel engines, Closed-cycle steam turbines Stirling cycle engines and Fuel cells.


Q1) What is the Strategic Partnership (SP) model?

The strategic partnership model seeks to identify a few Indian private companies as Strategic Partners who would initially tie up with a few shortlisted foreign Original Equipment Manufacturers (OEMs) to manufacture big-ticket military platforms. In the initial phase, the selection of SPs would be confined to four segments: Fighter Aircraft, Helicopters, Submarines, and Armoured Fighting Vehicles (AFV)/Main Battle Tanks (MBT).

Source: L&T, Nevantia join hands to bid for Indian Navy’s mega submarine acquisition programme