Depleting Submarine Strength Heightens Concerns for Navy  

By Girish Linganna 

Apr 13: After a span of 30 years, on Friday (March 24, 2024), in a notable achievement for the Indian Navy, the country successfully deployed a total 11 of its 16 conventional submarines for operational purposes. This milestone marks a significant advancement for the navy and highlights its enhanced capabilities. 

An unidentified Indian naval official, speaking anonymously to the media, expressed astonishment at the extensive simultaneous deployment, noting that such a large-scale operation had not been witnessed earlier. The reason behind this deployment was the limited number of submarines available for operations, as a significant portion of the fleet was undergoing maintenance or repairs, the official explained.

According to the Military Balance, 2024, report by the International Institute for Strategic Studies, India currently has 16 operational submarines. These include five Kalvari-class submarines (made in France), four Shishumar-class submarines (made in Germany) and seven Sindhugosh-class submarines (Russian Kilo class). Additionally, another Kalvari-class submarine is expected to join the navy soon, which will increase the total count to 17 submarines. 

However, a crucial factor to consider is the “operational availability” of the submarines, as mentioned by a naval source in an interview with an Indian media outlet. According to this official, the Kalvari-class submarines, being relatively new, have a significantly higher availability ratio. The Shishumar-class submarines, which originated in Germany, are also known for their reliability and performance, making them highly available for operations. These submarines are expected to remain in service for another 15 years.

The Russian Kilo-class submarines are regarded as “highly capable”, but their availability ratio has declined. These submarines were commissioned in the 1980s and have undergone several repairs and upgrades. However, due to their ageing condition, they are nearing decommissioning. The INS Sindhudhvaj, which served for 35 years, was retired from service in 2022 

Another Russian submarine was refurbished and transferred to Myanmar in 2020, while a third submarine, which was actually new, was lost in an accident in 2013. The German submarines in the Indian Navy have undergone the medium refit life certification (MRLC) process, which has extended their service life. It is possible that these submarines will remain in service for a longer period than their Russian counterparts. 

Air-Independent Propulsion System

While India’s significant achievement as mentioned at the beginning of this article is noteworthy, it is important to recognize that the Indian submarine fleet is shrinking. Without timely replenishment, the country’s submarine fleet could end up being similar to Pakistan’s—the only South Asian Navy with a submarine equipped with air-independent propulsion (AIP). 

Conventional submarines rely on diesel engines or batteries for power and need to come up to the surface or use a snorkel (a pipe that sticks out of the water) to get air for operations of their diesel engines which generate power to propel the craft and recharge their batteries. AIP submarines have a special technology that lets them stay underwater for a longer time without the need to come up for air, making them stealthier and more capable. While conventional submarines can stay underwater for a few days to a few weeks depending upon the submarine’s design and technology, those with AIP technology can remain submerged for several weeks to months. 

6 Advanced Submarines in the Pipeline

The Indian Navy’s plan to acquire six advanced submarines is experiencing significant delays, with an estimated delay of 10 years. It is unlikely that the first submarine from this batch will be delivered before 2030.

Germany is actively pursuing an inter-government agreement to provide India with new submarines. Currently, Germany and Spain are in competition for the lucrative deal worth over $5 billion, as of February. Thyssenkrupp Marine Systems (TKMS) from Germany and Navantia, a state-owned company from Spain, are the top contenders in the final stage of the competition. They have both fulfilled the various criteria specified by the Indian Navy for the acquisition of six P-75I submarines.

Spain’s Navantia has formed a partnership with Larsen & Toubro, an Indian company, while Germany’s TKMS has established collaboration with Mazagon Dock Shipbuilders Limited (MDL). According to the agreement between Navantia and L&T, the former will be responsible for the design of the P-75I submarines, while the latter will undertake the construction of the submarines. Navantia’s design of the submarines will be based on Spain’s S-80-class, introduced in 2021, while Germany has put forward a proposal for a government-to-government agreement to sell the six submarines to India. 

According to Indian officials who have provided information to the media, the new submarines to be inducted should be equipped with reliable AIP system, enabling the vessels to remain submerged for two weeks and more. Based on recent reports, evaluations have been conducted on both bids and some initial assessments have been made. It is reported that Navantia has shown its ability and agreed to transfer the necessary technology. Navantia’s AIP module is considered more effective. Also, being a government-owned entity, Navantia offers greater assurance through government guarantees.

Challenges of Overall Size of Indian Navy

In addition to concerns about India’s underwater combat capabilities, there are also challenges regarding the overall size of its navy. India has ambitious goals to expand its fleet by 2050, but various constraints, such as budget limitations and expansion problems, pose significant obstacles to achieving these plans. Considering India’s strategic needs and extensive coastline, India aims to possess a fleet of approximately 155-160 warships—including submarines, aircraft carriers, destroyers, frigates and other types of vessels—by 2030. This aligns with India’s broader plan to enhance its naval capabilities and safeguard maritime security in the Indian Ocean Region (IOR).

However, an unnamed official source stated that the numbers might vary. The current goal is to have at least 175 warships and, possibly, up to 200 by 2035. This objective is aimed at establishing a strong strategic presence, improved mobility and flexibility in the IOR and potentially in other areas, as well. To support the expanded fleet, there will also need to be a proportional rise in the number of fighter jets, aircraft, helicopters and drones. 

India’s Limited Access to Stealth Technology

India’s response to China’s increasing maritime power has led to a greater focus on strengthening its naval capabilities. However, the pace of domestic production and acquisition has not kept up with the Indian Navy’s objectives. Such factors as limited access to stealth technology, financial constraints and a lack of serial production capabilities have all contributed to delays in the Indian acquisition process and have resulted in a decline in the size of the Indian naval fleet.

Stealth technology refers to techniques and technologies used to make objects—such as military vehicles or aircraft—less detectable by radar, sonar, or other detection systems. It involves the use of special materials and design features to reduce the object’s visibility and make it harder to track. The goal is to enhance the object’s ability to operate covertly and avoid detection in various environments.




(The author Girish Linganna of this article is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach him at:




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