February 27, 2024

India’s Deisel-Electric Submarine Fleet Upgrade

Article by Mr. Ankit Kumar

As per the latest GDP estimates, India has the fifth-largest economy in the world. It is expected to surpass Germany and grab the fourth spot by the end of the decade, possibly surpassing Japan by the start of the next decade. This prosperity for the citizens of India depends on the sea.

India has one of the largest and most capable naval fleets in the world. And this does a huge job of ensuring the protection of India’s sea lines of communication for trade and commerce, protecting the natural resources in India’s Exclusive Economic Zone and conducting disaster response whenever required.

Naval warfare is a multi-faceted domain of warfare and one among them is underwater warfare led by Submarines. A domain in which India is trying to quickly fill up the crucial gaps in capability. A potent and modern submarine fleet is enough to choke the sea-based trade of any nation if utilised effectively. Since the days of German Wolfpacks in the northern Pacific during World War 2 to today renewed interest by multiple nations to acquire the capability to ward off a bigger and more powerful adversary.

To counter the threat of submarines, Anti-Submarine Warfare concepts were developed but these specialised techniques take up a lot of capital resources as well as time and have their own lacune to count for thus, ensuring the relevance of submarines even today. Diesel Electric Submarines with some form of Air Independent Propulsion and the capability to fire missiles while being submerged is the most sought-after capability by the navies around the world today.

Naval warfare is a multi-faceted domain of warfare

Where Does India Stand?

With a fleet of legacy-era Kilo 877 EKM submarines, Type 209 Mod 1500 submarines and the more modern Kalvari Class submarine, India has blue water reach but misses several critical capabilities. Some of which are enjoyed by our adversaries like Pakistan and China.

India has blue water reach but misses several critical capabilities

The Indian Navy currently has: –

  • 07 Sindhughosh Class (Kilo 877 EKM) submarines
  • 04 Shishumar Class (Type 209 Mod 1500) submarines
  • 05 Kalvari (Scorpene) Class submarines

More than half of the fleet is now near the 30-year service mark and the newer Kalvari class submarines still do not have an Air Independent Propulsion System along with the absence of a contemporary heavy weight wire guided torpedo. These gaps put several doubts on the capability of the Navy to conduct all its tasks successfully.

Critical Challenges Ahead

India has put considerable effort to modernize its naval fleet, especially after a third-pronged threat from China in the Indian Ocean Region (IOR), keeping the regional vision in perspective such as the SAGAR initiative to ensure sustainable shared and mutually benefiting relationships in the IOR. However, among a myriad of interwoven issues, we can clearly take out 4 problems which are causing delays in the necessary modernisation of the Indian Navy submarine fleet. These issues consist: –

  1. DELAYS: There have been numerous delays in the design and building of Indian submarines. The Project 75 Kalvari program has been delayed with the 6th and final submarine still not commissioned into the navy. Further, there are delays on the part of the decision-making level at the Ministry of Defence, Indian Navy and Prime Minister’s Office as is shown by the failure of India to conclude the deal for 6 Project 75I submarines in more than 10 years now.
  2. COST OVERRUNS: A significant issue has been the price of Indian submarines. For instance, Indian Navy will pay 340 million USD for the refit and life extension of a Type 209 submarine. Newer diesel-electric submarines under Project 75I are touted to cost over 1 billion USD per piece. Small order numbers, stringent customisations and lack of alternatives often drive up the costs to sky limits.
  3. TECHNOLOGY: India has encountered a variety of technological difficulties while developing its submarines. India has a dedicated research and development capability but lack of funding, and necessary testing infrastructure among other things still hamper the development of various technologies and sub-systems for the submarines. Proven domestic technology will solve a lot of issues including cost overruns and delays.
  4. FOREIGN DEPENDENCE: India has been heavily dependent on foreign suppliers for the components of its submarines. This has made India vulnerable to supply disruptions and has increased the cost of the submarines. Foreign vendors further often back up from their promises resulting in lower serviceability of Indian Submarines.

Putting Plans Into Actions

Considering the problems in the segment India has had well laid out plans and blueprints since long but it’s only now that we are able to see some of them put into action on the ground.

  1. UPGRADE OF LEGACY PLATFORMS: Type 209s and Kilos of the Indian Navy are being upgraded in a phased manner to keep up their contemporary combat capabilities. Harpoon Cruise Missiles for Type 209s and Klub Cruise Missiles for the Kilos are critical capabilities which make the platforms of the Indian Navy one of the most potent offensive platforms in the world. The capability to launch long-range cruise missiles from submarines is present only in a handful of nations worldwide. Sonars, self-defence suites, optronics, etc are the other equipment upgraded to keep the platforms combat capable.
  2. ACQUIRING MORE SUBMARINES: The Indian Navy is working to acquire more diesel-electric submarines in the coming years. These include: –
  • 03x Kalvari-class follow on submarines. India has signed an MoU with France for building 03 more Kalvari Class submarines in India by MDSL.
  • 06x P75 India submarines. MDSL-TKMS(Germany) and L&T-Navantia(Spain) are the two bidders currently vying for the multi-billion dollar deal by Indian Navy. RFP for the same is expected soon.
  • 06x P76 Indigenous Diesel Electric Submarine.

These can further replace the Type 209s and Kilo Class submarines of the Indian Navy in the next 15 years to make Indian Navy one of the largest diesel-electric submarine operators.

3. DEVELOPING INDIGENOUS SUBMARINE TECHNOLOGY: India is also working to develop its own submarine technology. This includes the development of a new nuclear reactor for submarines and the development of new weapons systems for submarines. India is also developing the necessary subsystems for these platforms so that the dependence on foreign OEMs (Original Equipment Manufacturers) can be reduced further. This will allow India the necessary flexibility even on platforms based on foreign designs like Kalvari Class. However, all this will require close support from friendly countries, which only a few countries can offer.

All this will require close support from friendly countries, which only a few countries can offer


Pakistan, an adversary is already invested in a program to procure 08 diesel-electric submarines from China to boost its numbers from the current 5 platforms to 11. Bangladesh, Myanmar, and Indonesia are other important players around India’s periphery who are seriously investing in submarine capability. China with its new infrastructure push around India has multiple dual-use capable ports ready which can serve its submarines prowling the Indian Ocean Region. If India wants to hold the capability of a net security provider for the IOR, submarines are an absolute necessity. The comparison with Aircraft Carriers shouldn’t be allowed to hold back any progress in the submarine modernisation programs as each one of them have its own specific roles which the other cannot fulfil.


  • Ankit Kumar

    An independent analyst with engineering background. Besides covering military affairs, he is also interested in space, airlines, infrastructure, nuclear, energy and related issues.

Leave a Reply

Your email address will not be published. Required fields are marked *