New Delhi: India Scorpene submarine programme is becoming an important part of the country’s journey towards defence self-reliance. Built through cooperation between India and France, the programme has delivered six advanced Kalvari-class submarines to the Indian Navy under Project 75.
However, the partnership goes beyond submarine construction. It is helping India develop indigenous technologies, strengthen domestic manufacturing and improve its underwater warfare capabilities. With DRDO’s Air Independent Propulsion (AIP) system progressing towards integration, India is now looking at the next phase of submarine technology and industrial cooperation.
Details of India-France Scorpene Partnership
The India-France Scorpene partnership began in October 2005, when both countries signed agreements for the construction of six Scorpene-class submarines under Project 75.
Under this arrangement, the submarines were built by Mazagon Dock Shipbuilders Limited (MDL) in Mumbai with technical assistance and technology transfer from France’s Naval Group, formerly known as DCNS.
The main objective was not simply to purchase six submarines. India also wanted to develop its domestic submarine-building capabilities and gain experience in advanced naval engineering.
Submarine construction requires specialised technology, highly skilled workers and advanced manufacturing facilities. These vessels must operate under extreme underwater pressure while maintaining high standards of safety, stealth and performance.
The first submarine, INS Kalvari, was launched on 27 October 2015. After completing its trials, it was commissioned into the Indian Navy on 14 December 2017.
Over the following years, five more submarines joined the fleet, completing the original six-submarine Project 75 programme.
The sixth submarine, INS Vaghsheer, was delivered to the Indian Navy on 9 January 2025 and commissioned on 15 January 2025. The six submarines delivered under Project 75 are:
| Submarine | Commissioning Date |
| INS Kalvari | December 2017 |
| INS Khanderi | September 2019 |
| INS Karanj | March 2021 |
| INS Vela | November 2021 |
| INS Vagir | January 2023 |
| INS Vaghsheer | January 2025 |
Completing this programme was a major achievement for India’s shipbuilding industry. It demonstrated that an Indian shipyard could construct sophisticated conventional submarines with international technical cooperation.
India-France Naval Partnership: The Industrial Achievement Behind Project 75
One of the most important contributions of the Scorpene programme is the development of India’s submarine manufacturing ecosystem.
MDL had to adopt advanced manufacturing techniques, specialised equipment, precision engineering and complex system-integration processes to construct these submarines.
An important milestone came during the construction of INS Kalvari in July 2014. Five separate sections of the submarine were joined using a modular construction method.
This approach allows different sections of a submarine to be manufactured and equipped separately before being assembled into the final vessel. However, submarine construction requires extremely high levels of precision. Even small manufacturing errors can affect the vessel’s safety, structural strength and operational performance.
The technology transfer arrangement also helped Indian engineers develop expertise in submarine design documentation, hull fabrication, equipment installation and system integration.
These capabilities are important because submarine manufacturing does not end when a vessel is delivered.
A submarine requires specialised maintenance, spare parts, technical upgrades and engineering support throughout its operational life. Therefore, the experience gained through Project 75 provides a foundation for future submarine construction and maintenance programmes in India.
What Makes The Scorpene-Class Submarine Capable
The Kalvari-class submarines are diesel-electric attack submarines based on France’s Scorpene design. They are designed to perform multiple underwater missions, including anti-submarine warfare, anti-surface warfare, intelligence gathering and surveillance.
One of their important features is their low acoustic signature. In simple terms, they are designed to produce less noise underwater, making them more difficult for hostile forces to detect.
The submarines also use specialised acoustic technologies and an advanced combat management system to help their crews identify, track and respond to underwater and surface threats. Their combat capabilities include heavyweight torpedoes and the SM39 Exocet anti-ship missile.
They are also equipped with sonar systems that help detect and classify underwater and surface contacts. Another important feature is the integration of different sensors and weapons through the submarine’s combat management system.
Instead of operating independently, these systems work together to provide information that helps the crew make important operational decisions.
Such capabilities are particularly important in submarine warfare, where visibility is limited and decisions often have to be made using incomplete information.
The Next Step in India-France Naval Partnership
If 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 capabilities.
One major example is the indigenous Air Independent Propulsion (AIP) system being developed by the Defence Research and Development Organisation (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 draw in air, creating opportunities for detection. An AIP system helps address this limitation.
It allows a conventional submarine to generate power underwater without continuously depending on atmospheric oxygen. This can significantly increase submerged endurance and reduce the need for frequent snorkelling.
India’s fuel-cell-based AIP system is an important step towards improving the underwater capabilities of its conventional submarine fleet.
The programme also involves cooperation with the Naval Group. In January 2023, DRDO and Naval Group signed an agreement to advance the detailed design phase for integrating the indigenous AIP system into Kalvari-class submarines.
Naval Group provides design certification support for the integration process. The programme achieved another important milestone on 24 October 2026.
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 Mazagon Dock Shipbuilders Limited for integration into a Kalvari-class submarine in early 2027.
This is an important development because it brings together Indian research, domestic industrial manufacturing and international engineering cooperation.
India-France Naval Partnership: DRDO’s Heavyweight Torpedo Integration
Another important development is the integration of the DRDO-developed Electronic Heavy Weight Torpedo (EHWT) into Kalvari-class submarines.
In December 2024, the Ministry of Defence signed a contract worth approximately ₹877 crore with Naval Group for this project. The programme involves cooperation between the Indian Navy, DRDO and Naval Group.
The integration of indigenous weapons and propulsion technologies can gradually reduce India’s dependence on foreign suppliers.
It also demonstrates that defence indigenisation involves much more than manufacturing a submarine’s external structure. It requires the development and integration of critical technologies that influence underwater endurance, combat capabilities and long-term operational performance.
Could India Build More Scorpene-Class Submarines
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 to construct three additional Scorpene-class submarines under a follow-on programme.
The proposal received Acceptance of Necessity (AoN) from the Defence Acquisition Council in July 2023. However, receiving AoN does not mean that a final purchase contract has been signed.
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). Therefore, the proposed three submarines should not yet be treated as a confirmed acquisition.
Nevertheless, a follow-on programme could provide an opportunity to build upon the industrial experience developed during the original Project 75. The proposed approach could involve greater participation from Indian manufacturers and the integration of more indigenous technologies.
These could include 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.
For India, the larger objective is to move beyond assembling foreign-designed platforms domestically and gradually develop the ability to design, manufacture, integrate and maintain critical submarine technologies.
India-France Naval Partnership: A Partnership Looking Beyond The Present
The Scorpene programme is part of the much broader India-France defence relationship. For Naval Group, its involvement in India extends beyond the original submarine 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, sourcing, quality control, maintenance, repair, spare parts management and lifecycle support. This is particularly important for submarine operations.
Unlike many conventional defence platforms, submarines require specialised technical support throughout their operational lives.
The availability of trained engineers, spare parts and maintenance facilities can directly affect the operational readiness of a submarine fleet. Therefore, long-term cooperation between the original equipment manufacturer and India’s domestic industrial ecosystem remains important even after submarine construction is completed.
The wider India-France 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 relations to a Special Global Strategic Partnership.
The leaders also recognised progress in the Made-in-India Scorpene programme and welcomed continued cooperation in submarine construction.
They emphasised joint research, co-design, co-development and co-production of advanced defence platforms.
This broader approach is important for India’s defence industry because future international partnerships are expected to involve more than purchasing foreign equipment.
They can also help Indian companies participate in research, engineering, manufacturing and technological development.
From Building Submarines To Building Indigenous Capabilities
The Scorpene programme offers an important lesson about India’s defence indigenisation journey.
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 domestic industrial ecosystem. However, considerable work remains.
India needs to strengthen its conventional submarine fleet, expand indigenous research, improve manufacturing capacity and develop more domestic suppliers for sophisticated underwater systems.
The experience gained through the Scorpene programme provides an important foundation for these future efforts. The next phase of the partnership should not be judged only by the number of submarines delivered.
Its greater importance will lie in how much technology, engineering expertise and manufacturing capability India develops for future generations of submarines.
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 underwater warfare.
Read also: German Technology, Make In India: Project 75I Submarine Deal Enters Final Stage
FAQs
The Defence Research and Development Organisation (DRDO), through its Naval Materials Research Laboratory (NMRL), is developing the indigenous fuel-cell-based Air Independent Propulsion system for Kalvari-class submarines.
India has built six Kalvari-class Scorpene submarines under Project 75. The sixth submarine, INS Vaghsheer, was commissioned into the Indian Navy on 15 January 2025.
India is considering a proposal for three additional Scorpene-class submarines. The proposal received Acceptance of Necessity in July 2023, but it should not be treated as a signed acquisition. Its final approval and contractual status remain important steps.
