Ever since they first made a deadly impact in early 20th century naval warfare, submarines have been silent and unseen guardians of the deep. Essential for navies for surveillance, tracking and pursuit, and destruction of hostile platforms, they have acquired added relevance in the nuclear age.

PROUD ADDITION: The launch ceremony of the Kalvari-class submarine INS Vagsheer in Mumbai, Apr. 20, 2022. (Photo: ANI)

Now, the Indian Navy is gearing up for its biggest-ever submarine acquisition programme, Project 75 (India) or P75(I). Initiated in 1997, the Rs 43,000 crore progra­mme aims to build six advanced diesel-electric conventi­onal submarines, equipped with better sensors, weapons and air-independent propulsion (AIP) systems through a joint venture.

AIP systems allow non-nuclear submarines to stay submerged for as long as 12 days at a stretch, enhancing stealth capabilities. As per the Navy’s request for proposal (RFP), the first submarine should have indigenous content of 45 per cent, which should go up to 60 per cent for the sixth submarine. Also, it stipulates that the first submarine be rolled out 84 months or seven years from the signing of the contract.

After years of deliberations with several manufacturers, Spanish state-owned firm Navantia and German company ThyssenKrupp Marine Systems (TKMS) are left in the race for the P75(I) contract. The mega-submarine deal crossed a milestone with the completion of Field Evaluation Trials (FET) to check the compliance of the submarines offered with the navy’s RFP.

While an Indian Navy team visited the TKMS shipyard in March for the FET, Navantia’s offer was evaluated in late June. TKMS has tied up with the Mumbai-based Mazagon Dock Shipbuilders Ltd (MDL), and Indian firm Larsen & Toubro (L&T) with Navantia to build the submarines. The Germans are said to have gained the upper hand in the FETs with their Type 212 submari­nes, as Navantia failed the navy’s stringent AIP requirements. The navy has submitted its report to the defence ministry.

P75(I) assumes importance because India’s submarine fleet is down to just 16 in contrast to the fast increasing fleets of its adversaries, China and Pakistan. Only half the Indian subs are battle-ready at any given time; the rest are undergoing upgrades.

True, with the commissioning of INS Arighat on August 29, India has two indigenously made nuclear-powered ballistic missile submarines (SSBNs), has a plan to acquire a fleet of nuclear-powered conventional attack submarines (SSNs) and already operates five diesel-electric attack subma­rines of the Scorpene-class (that have the same base blueprint and are named after the first vessel of the type). But it needs to beef up its ageing fleet of conventional submarines, a gap the latest vessels would close.

Though India’s submarine force began its journey in 1967 with the induction of the Soviet-origin Kalvari (S-23), and the navy’s submarine strength went up to 21 diesel-powered attack subs by the mid-1980s, submarine programmes have hit rough weather in the last four decades.

They have been plagued by delays due to cost overruns and technolo­gical challenges, and acquisitions have attracted a volley of kickback accusations, be it over the purchase of submarines from the German firm Howaldtswerke-Deutsche Werft (HDW) in 1987, or the Scorpene deal in 2005.

Threat from China, Pakistan

China’s People’s Liberation Army Navy (PLAN) has rapidly expanded and modernised its now 50-strong submarine fleet, with both conventional diesel-electric submarines and nuclear-powered vessels that include the Yuan-class conventional submarines, the Shang-class SSNs and the Jin-class SSBNs, which are capable of launching JL-2 missiles with intercontinental reach.

This growing heft underscores Beijing’s ambitions to project power in the Indo-Pacific region. The country has also been deploying its conventional and nuclear submarines in the Indian Ocean Region (IOR), controlling which is increasingly deemed important for India’s geostrategic aims. And naval experts believe the navy must have a full fleet of submarines to project India’s power in its backyard.

But China is not India’s only challenge. In 2015, Pakistan signed a contract with China to build eight Hangor-class submarines, an export variant of the Yuan-class submarines. In April 2024, China completed the first one. Pakistan aims to acquire all eight submarines by 2028, which could challenge India in terms of underwater warfare capability.

Experts believe the stealth submarines for Pakistan are Beijing’s way of “buil­ding a pressure point” on India. With AIP technology and advanced sensors, the Hangor-class subs have a clear advantage over India’s Scorpene-class vessels—the most advanced conventional subs the Navy possesses. This is reason enough for the government to expedite the P75(I) project. Vice Admiral A.K. Singh (retd), who commanded India’s first nuclear-powered submarine INS Chakra, says unequivocally, “Our underwater capabilit­ies are pathetic; it’s high time we speed up.”

Journey of Indian submarines

Throughout the 1970s, India exp­anded its submarine fleet with Fox­trot-class submarines like the Kalvari. From 1986, the Navy took a significant step forward with the acquisition of the Shishumar-class submarines from West Germany. These Type 209 submarines were more advanced, featuring greater endurance, better sensors, and improved weaponry.

In the ’80s and ’90s, the navy acqu­ired the Sindhughosh-class (Kilo-class) submarines from the erstwhile Soviet Union and Russia. These subma­rines, equipped with advanced sonar systems and the capa­bility to launch cruise missiles, significantly enhanced India’s offen­sive capabilities. Once the backbone of India’s conventional submarine fleet, they are still in service, albeit with upgrades.

The early 2000s marked a new era in India’s submarine development, with the pursuit of nuclear-powered submari­nes capable of launching ballistic missi­les. This amb­ition was realised with the com­mi­ssioning of the SSBN INS Arihant in 2016. Developed under the secretive Advanced Technology Vessel (ATV) project, Arihant made India only the sixth nation to possess a nuclear-powered ballistic missile submarine, a key element of the country’s nuclear triad—the capability to launch nuclear missiles from land, air and sea. INS Arighat is India’s second SSBN, and a third, INS Aridaman, is in the pipeline.

The Modi government in 2015 approved Project Delta, under which India would lease six nuclear-powered SSNs (which lack the capability to launch long-range ballistic missiles) from Russia. However, the desired Akula-class SSNs were delayed due to Russia’s preoccupation with the Ukraine conflict, the navy has now moved a proposal to indigenously build two SSNs.

India’s efforts to modernise its conventional submarine fleet also led to the 2005 contract for six French Scorpene-class diesel-electric attack submarines. They were developed in collaboration with the French company Naval Group and built by MDL. The first of these submarines, the INS Kalvari (named after India’s first submarine, and which lends its name to the class), was commissioned in 2017. Four more Kalvari-class submarines were inducted in the following years, with the sixth one expected later this year. Sensing the growing need for advanced conventional submarines, the Navy in 2021 approved the acquisition of three additional Kalvari-class submarines. MDL is in advanced talks for a potential Rs 35,000 crore deal for the three vessels that will be larger and more advanced than the first six.

With advanced stealth features and the capability to launch Exocet anti-ship missiles, the Kalvari-class submarines are a significant upgrade over the Sindhughosh and Shishumar classes, but they lack the AIP technology and sensors of the most advanced conventional subs. The Project 75(I) submarines would address this shortcoming.

“The contract for Scorpenes was signed in 2005, but it ran behind schedule and cost almost twice as much. This led to the obsolescence of equipment,” says a serving navy submariner. According to him, the lack of AIP is a major limitation in deploying subs in anti-submarine warfare. “Even Pakistan,” he says, “has had AIP capability on its submarines since 2005, ironically delivered by the French.”

Full transfer of technology

Despite its strategic importance, P75(I), too, has faced delays, with momentum picking up in 2021. Vice Admiral Singh believes that India desperately needs P75(I), but he is apprehensive about its projected timeline (seven years for the first sub). He points out that both Indian submarine manufacturing shipyards—the MDL in Mumbai and the L&T shipyard near Ennore in Tamil Nadu—have their hands full. “MDL is gearing up for three additional submarines, while L&T is on a nuclear sub. Unless we find a third shipyard, we do not see Project 75(I) translated into reality,” he says.

As for its current status, after the FET by the Indian Navy, the Spanish firm Navantia is at a pronounced disadvantage as they are yet to have a proven AIP. However, being state-owned, they offer crucial governmental support and guarantees. Navantia has offered a submarine based on its new S80 class. In contrast, the German TKMS has built over 170 submarines for 15 navies, and 52 of them have time-tested fuel cell AIP systems that are being offered to India.

Khalil Rahman, chief executive off­icer, TKMS India, says the propo­sed deal has the full backing of the German government. He says TKMS promises a full transfer of technology as India has demanded, stressing that Germany will guarantee it. “The design is a derivative of the HDW Class 214. It is adapted to fulfil the P-75(I) requirem­ents. ThyssenKrupp Marine Systems is a forerunner in stealth technology and the only provider of a sea-proven fuel cell AIP system which dramatically increases the range at which a submarine can remain undetected,” Khalil tells india today.

Whether it chooses Navantia or TKMS, India must expedite Project 75(I), addressing the constraints that have contributed to the country’s declining fleet size.