Beyond Six Submarines: How the India-France Scorpene Partnership Is Strengthening India’s Indigenous Naval Capabilities

From technology transfer and submarine construction at Mazagon Dock to the integration of DRDO-developed technologies, the Scorpene programme represents an important chapter in India’s journey towards greater self-reliance in underwater warfare.

An advanced submarine is not built in a day. Nor does a country become a submarine-building nation simply by acquiring the technology to construct one. The real achievement lies in developing the engineers, industrial infrastructure, manufacturing processes and technical expertise needed to build, maintain and eventually improve such a complex platform.

India’s Scorpene submarine programme offers an interesting example of this journey.

What began as a technology partnership between India and France has evolved into a much broader industrial relationship, bringing together the Indian Navy, Mazagon Dock Shipbuilders Limited (MDL), India’s defence industry and France’s Naval Group.

Today, all six submarines under Project 75 have joined the Indian Navy. Yet, the programme’s significance extends well beyond the delivery of these vessels. Its legacy can also be seen in the experience gained by Indian shipyards, the growing role of domestic suppliers and the ongoing effort to integrate Indian-developed technologies into the fleet.

As India looks towards the next phase of its underwater warfare capabilities, the Scorpene partnership provides a useful starting point for understanding how international collaboration can support indigenous defence manufacturing.

From a French Design to an Indian-Built Submarine Fleet

The story began in October 2005, when India and France signed contracts for the construction of six Scorpene-class submarines under Project 75.

The arrangement was based on a transfer-of-technology model. The submarines would be constructed at Mazagon Dock in Mumbai using French design expertise and technical assistance from France’s then DCNS, now Naval Group.

The objective was not limited to acquiring six submarines. India’s longer-term submarine-building plans also aimed to develop domestic competence in constructing conventional submarines. The original Ministry of Defence announcement specifically highlighted the importance of building national expertise in this field.

This distinction matters. Submarine construction involves a level of engineering complexity that goes far beyond conventional shipbuilding. A submarine must withstand immense underwater pressure while maintaining exceptionally demanding standards of safety, acoustic performance, precision and system integration.

The first submarine, INS Kalvari, was launched at MDL on 27 October 2015. Following an extensive series of trials, it was commissioned into the Indian Navy on 14 December 2017.

Over the following years, five more submarines joined the fleet, completing the six-boat Project 75 programme.

The sixth submarine, INS Vagsheer, was delivered to the Indian Navy on 9 January 2025 after completing mandatory sea trials. It was subsequently commissioned on 15 January 2025, marking the completion of the programme.

The six submarines are:

For India, completing this programme meant more than adding six conventional submarines to its naval inventory. It demonstrated the ability of an Indian shipyard to undertake the construction of a sophisticated underwater platform with support from an international technology partner.

Also Read, Hangor-Class vs Kalvari-Class

The Industrial Achievement Behind Project 75

One of the most significant aspects of the Scorpene programme is the development of indigenous submarine manufacturing capabilities.

The construction process required MDL to work with advanced manufacturing techniques, specialised equipment, precision engineering and complex integration procedures.

An interesting milestone came during the construction of INS Kalvari. In July 2014, five separate sections of the submarine were joined together using a modular construction approach. According to the Ministry of Defence, Kalvari was the first Indian naval vessel to be built using this method.

This was an important development because modular construction allows different sections of a vessel to be manufactured and equipped before being assembled into the final platform. For submarines, however, the process demands exceptionally high levels of precision because even small errors can affect the structural integrity and performance of the vessel.

The technology transfer agreement also included a Technical Data Package to help develop indigenous competence in areas such as hull fabrication, outfitting and system integration.

The journey was not without challenges. A 2012 Ministry of Defence statement acknowledged initial difficulties in absorbing new technology, expanding industrial infrastructure at MDL and procuring specialised equipment. These challenges reflect the learning curve involved when a shipyard takes on a highly complex platform.

But that is precisely where the long-term value of such partnerships lies. The experience gained during one project can provide a foundation for future construction, upgrades and maintenance activities.

The importance of this industrial ecosystem becomes even clearer when one considers that submarines require decades of technical support. Their operational life depends not just on the original construction but also on the availability of specialised spares, maintenance infrastructure, system upgrades and engineering support.

For Indian industry, developing these capabilities at home is an important step towards reducing dependence on external support.

What Makes the Scorpene a Capable Conventional Submarine?

The Kalvari-class submarines are diesel-electric attack submarines based on Naval Group’s Scorpene design.

Their primary strength lies in their ability to conduct underwater operations while maintaining a low acoustic signature. In submarine warfare, remaining difficult to detect can be just as important as the ability to engage a target. The Scorpene design incorporates acoustic absorption techniques, low radiated noise levels and a hydrodynamically optimised hull shape. These features help reduce the submarine’s chances of being detected by hostile underwater sensors.

The Indian Navy’s INS Kalvari also features an advanced sonar suite, integrated combat management systems and a combination of torpedoes and anti-ship missiles. The submarine’s sonar suite includes Low Frequency Analysis and Ranging (LOFAR) capabilities, which assist in detecting and classifying underwater and surface contacts.

For offensive operations, the Kalvari-class configuration includes the SM39 Exocet anti-ship missile and heavyweight torpedoes. It is also equipped with mobile anti-torpedo decoys for self-defence.

Another important feature is the integration of different sensors and weapons through the submarine’s tactical combat system. Instead of functioning independently, these systems work together to provide the crew with information required for tactical decision-making.

Such integration is particularly important in submarine operations, where situational awareness is limited and decisions often have to be taken with incomplete information. The Kalvari-class therefore combines stealth-oriented design, underwater detection capabilities and a sophisticated weapon suite in a conventional submarine platform.

The Next Step: Bringing More Indigenous Technology Underwater

If the original Project 75 demonstrated India’s ability to construct advanced submarines with foreign technical assistance, the next challenge is to increase the role of Indian-developed technologies in their operation and capabilities.

A major example is the indigenous Air Independent Propulsion (AIP) system being developed by the DRDO through its Naval Materials Research Laboratory (NMRL).

Conventional diesel-electric submarines depend on atmospheric oxygen to operate their diesel engines and recharge their batteries. This means they periodically need to surface or use a snorkel to replenish their air supply, creating opportunities for detection.

An AIP system changes this equation.

It allows a conventional submarine to generate power underwater without continuously depending on atmospheric oxygen. This can significantly extend submerged endurance and reduce the need for frequent snorkelling.

DRDO’s fuel-cell-based AIP system is an important Indian effort in this area.

The programme has also involved cooperation with Naval Group. In January 2023, DRDO and Naval Group signed an agreement to take forward the detailed design phase for safely integrating the indigenous AIP system into Kalvari-class submarines, with Naval Group providing design certification support.

The programme has achieved another important milestone in October 2026.

On 24 October, the Ministry of Defence announced the inauguration of Setting to Work Phase-2 activity for the indigenous AIP Energy Module at Larsen & Toubro’s AM Naik Heavy Engineering Complex in Hazira, Gujarat.

The next stage will involve energising the module for power production and conducting extensive testing under Indian Navy protocols. Following successful validation, the module is scheduled to be handed over to MDL for integration into a Kalvari-class submarine in early 2027. This is an important development because it demonstrates how Indian research, domestic industrial capability and international engineering cooperation can come together to upgrade an existing submarine fleet.

Another significant development concerns the Electronic Heavy Weight Torpedo (EHWT).

In December 2024, the Ministry of Defence signed a contract worth approximately Rs 877 crore with Naval Group for the integration of the DRDO-developed EHWT onto Kalvari-class submarines. The project is a collaborative effort involving the Indian Navy, DRDO and Naval Group.

Together, these developments demonstrate that indigenisation is not restricted to manufacturing the submarine’s external structure. It also involves progressively developing and integrating critical technologies that influence the platform’s endurance, combat capabilities and long-term operational value.

Could India’s Next Scorpene Submarines Be More Indigenous?

With all six Project 75 submarines delivered, attention is now turning towards the possibility of expanding the Kalvari-class fleet.

India has been considering a proposal for three additional Scorpene-class submarines, often referred to as the additional Scorpene programme.

The proposal received an Acceptance of Necessity from the Defence Acquisition Council in July 2023. However, its contractual status needs to be understood carefully.

On 1 October 2026, Defence Secretary Rajesh Kumar Singh stated that the additional Scorpene submarines were still under consideration and that the proposal was not as advanced as Project 75(I).

This means the proposed submarines should not yet be treated as a signed acquisition. Nevertheless, a follow-on programme could offer an opportunity to build upon the industrial experience developed during the original Project 75.

The proposed vision includes greater participation of Indian technologies and components, potentially covering DRDO-developed systems, indigenous weapons, batteries, combat systems and other locally sourced equipment.

The final configuration would depend on government approval, technical requirements and contractual negotiations. However, the direction is significant: India is looking to move beyond simply constructing foreign-designed platforms domestically towards integrating a growing range of indigenous systems into them.

For Naval Group, this also represents an opportunity to deepen its role as a technology and industrial partner.

Instead of a conventional buyer-supplier relationship, the next phase could involve closer cooperation between Indian research organisations, domestic manufacturers, the Indian Navy and French engineering specialists. The success of such an approach would ultimately be measured by the capabilities developed within India and the extent to which domestic industry can independently manufacture, integrate, maintain and improve critical submarine systems.

Naval Group and India: A Partnership Looking Beyond the Present

The Scorpene programme is part of a much broader India-France defence relationship.

For Naval Group, its engagement in India extends beyond the original construction contract. Naval Group India, established in 2008, has developed a local presence to support submarine programmes and India’s maritime self-reliance ambitions.

Its activities include engineering, procurement and sourcing, quality control, maintenance, repair, spare parts management and lifecycle support for the Kalvari-class fleet.

This is an important aspect of submarine cooperation. A submarine is not a conventional defence product that can simply be delivered and forgotten. It requires specialised support throughout its operational life. The availability of technical expertise, spare parts and maintenance capabilities can have a direct bearing on fleet readiness.

For this reason, a long-term partnership between the original equipment manufacturer and the Indian industrial ecosystem remains important even after the construction of the submarines is completed.

Naval Group has also expressed its intention to continue working alongside the Indian Navy and Indian industry over the next 25 years. Such a commitment, if sustained through practical industrial cooperation, could help create further opportunities in maintenance, technology development, indigenous sourcing and future naval programmes.

The wider relationship has also gained political momentum. India and France marked the 25th anniversary of their Strategic Partnership in 2023 and adopted the Horizon 2047 Roadmap, outlining a long-term vision for bilateral cooperation.

During French President Emmanuel Macron’s visit to India in February 2026, Prime Minister Narendra Modi and President Macron elevated bilateral ties to a Special Global Strategic Partnership. Importantly, their joint statement specifically recognised the success of the Made-in-India Scorpene programme and welcomed the continuation of submarine cooperation.

The leaders also committed to strengthening joint research, co-design, co-development and co-production of advanced defence platforms. This broader approach is particularly relevant to India’s defence industry. Future partnerships are increasingly expected to go beyond procurement and include meaningful domestic participation in design, development, manufacturing and technological advancement.

From Building Submarines to Building Capabilities

The Scorpene programme offers an important lesson about defence indigenisation.

A country cannot become technologically self-reliant simply by replacing imported equipment with locally manufactured products. It must also develop the expertise to understand complex systems, integrate them, maintain them and eventually improve their design and performance. Project 75 has contributed to this journey by bringing together an Indian shipyard, a foreign technology partner, the Indian Navy and a wider industrial ecosystem.

There is still considerable work ahead. India needs to strengthen its conventional submarine fleet, expand indigenous research, improve production capacity and develop more domestic suppliers for sophisticated underwater systems.

But the experience gained through the Scorpene programme provides an important foundation. The next chapter of this partnership should not be judged only by the number of submarines delivered. Its greater significance will lie in how much technology, engineering expertise and manufacturing capability India continues to develop.

The Scorpene journey began with a French design and an Indian ambition. Its lasting contribution could be the industrial and technological capabilities that India carries forward into the next generation of submarines.