Naval Group Shares Technical Know-How on Kalvari-Class Submarine Hull Systems With Indian Navy

French defence major Naval Group has shared its technical expertise on hull systems used in India's Kalvari-class submarines during a specialised seminar organised by the Indian Navy, highlighting ongoing cooperation in submarine maintenance, sustainment and modernisation. Naval Group India participated in the Submarine Hull Maintenance, Sustainment and AIP Jumboisation seminar organised by the Indian Navy's HITU (MBI) at the Western Naval Command on October 29, 2026. The company delivered a presentation focusing on hull systems incorporated into the Kalvari-class submarines and the technical requirements associated with their maintenance.

The interaction comes as the Indian Navy works to strengthen the operational readiness of its conventional submarine fleet while preparing for future technological upgrades, particularly the integration of an indigenous Air Independent Propulsion (AIP) system. Submarine hull maintenance is a critical part of underwater operations, as the structure must withstand immense water pressure while ensuring the safety of the crew and the reliability of onboard equipment. Regular inspections, specialised repairs and effective lifecycle management are essential to maintaining submarine availability.

The Kalvari-class submarines are based on the French Scorpène design and were constructed in India by Mazagon Dock Shipbuilders Limited (MDL) with technical assistance from Naval Group. The programme has played an important role in developing India's domestic submarine construction and maintenance capabilities.

A major focus of the seminar was AIP jumboisation, which involves modifying a submarine's hull to accommodate additional equipment required for an Air Independent Propulsion system. The technology enables conventional diesel-electric submarines to remain submerged for longer periods without needing to surface or use a snorkel to obtain atmospheric oxygen. India is developing its own AIP technology through the Defence Research and Development Organisation (DRDO). The indigenous system is expected to enhance the underwater endurance and operational flexibility of the Kalvari-class fleet.

Naval Group has maintained a long-standing presence in India's submarine programme through its Indian subsidiary, Naval Group India. Its activities include technical assistance, maintenance support, repair services, spare parts management and lifecycle support for submarine systems. The Indian Navy operates six Kalvari-class submarines: INS Kalvari, INS Khanderi, INS Karanj, INS Vela, INS Vagir and INS Vagsheer. The sixth submarine, INS Vagsheer, was commissioned in January 2025, completing the original six-submarine programme.

The latest knowledge-sharing initiative reflects the broader India-France defence partnership, which increasingly focuses on technology cooperation, indigenous capabilities and long-term support for military platforms. With plans for AIP integration and other modernisation initiatives underway, technical collaboration between Naval Group, the Indian Navy and domestic defence manufacturers is expected to remain important for sustaining India's conventional submarine fleet and strengthening its underwater warfare capabilities.

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