Explained: Submarine tech that India wants

What is the News?

France’s Naval Group, one of five shortlisted Original Equipment Manufacturers(OEM) for the Navy’s P-75 India(P-75I) project to build six conventional submarines within the country, has announced that it would not bid for the project. 


In 1999, the Cabinet Committee on Security approved a 30-year plan for the Navy to indigenously build and induct 24 submarines by 2030. 

In the first phase, two lines of production were to be established — the first, P-75; the second, P-75I. Each line was to produce six submarines.

What is P-75?

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What is P-75I?

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What is the status of the P-75I Project?

P-75I Project is running slightly behind the schedule due to the following reasons:

Firstly, the project requires the Original Equipment Manufacturers(OEM) to demonstrate a sea-proven fuel cell Air-independent propulsion(AIP). While some manufacturers may have the technology, it may not have been proven at sea yet.

Secondly, the other problem for the OEMs is the transfer of technology which is built into the process under the Strategic Partnership(SP) model. OEMs are unwilling to share all their expertise, especially the niche technologies that they have built.

What are Air-independent propulsion(AIP) Systems?

AIP technology allows a conventional submarine to remain submerged for much longer than ordinary diesel-electric submarines. 

All conventional submarines have to surface to run their generators that recharge the batteries that allow the boat to function underwater.

However, the more frequently a submarine surfaces, the higher the chances of it being detected. AIP allows a submarine to remain submerged for more than a fortnight compared to two to three days for diesel-electric boats.

Types of AIPs: There are different types of AIP mechanisms available; what India is looking for under the P-75I project is AIP based on fuel cells. These cells convert chemical energy into electrical energy, recharging the batteries of the submarine.

The backdrop of AIP: Installing AIP increases the length and weight of the boats as it requires pressurized Liquid OXygen(LOX) storage onboard and supplies for all three technologies.

What submarines does India have currently?

India has 16 conventional diesel-electric submarines which are classified as SSKs. After the last two Kalvari Class subs are commissioned under P-75, this number will go up to 18.

Of the 16 SSKs, four are of Shishumar Class which were bought and then built in India in collaboration with the Germans starting 1980s; eight are Kilo Class or Sindhughosh Class submarines bought from Russia (including erstwhile USSR) between 1984 and 2000 and four are Kalvari Class built in India at Mazagon Dock Shipbuilders Limited(MDL).

Note: India also has two nuclear ballistic submarines classified SSBN.

Source: The post is based on the article “Explained: Submarine tech that India wantspublished in Indian Express on 4th May 2022. 

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