Centre for Development of Advanced Computing's (C-DAC) Combat Management System

The Kalvari-class submarines represent a cornerstone of India’s naval modernisation, embodying the nation’s push towards self-reliance in underwater warfare. Derived from the French Scorpène design, these diesel-electric attack submarines are being constructed under Project 75 by Mazagon Dock Shipbuilders Limited in Mumbai, with technology transfer from Naval Group.

Six boats—INS Kalvari, INS Khanderi, INS Karanj, INS Vela, INS Vagir, and INS Vagsheer—are at various stages of commissioning, marking a pivotal shift in India’s maritime strategy.

These submarines integrate cutting-edge technologies tailored for stealth, survivability, and operational superiority. At their core lies an advanced combat management system (CMS), which fuses data from multiple sensors into a real-time tactical picture.

This C-DAC-developed CMS, known as the Submarine Combat Management System (SCMS), enables commanders to process threats swiftly, coordinate weapons deployment, and maintain situational awareness even in contested waters.

High-performance sonar suites form another pillar of their capability. Equipped with bow-mounted sonar, flank arrays, and towed arrays, the Kalvari class detects threats at extended ranges while minimising self-noise.

The hull-mounted sonar operates across low, medium, and high frequencies, allowing precise classification of surface ships, submarines, and torpedoes. Intercept sonars further enhance electronic warfare by capturing enemy acoustic signatures, providing India’s Navy with a decided edge in the noise-cluttered Indian Ocean.

Stealth remains paramount, with low acoustic signature features that make these submarines among the quietest diesel-electric platforms afloat. Advanced X-form stern planes reduce hydrodynamic noise, while raft-mounted propulsion systems isolate machinery vibrations.

The extensive use of elastomeric anechoic tiles coats the pressure hull, absorbing active sonar pings and scattering returns. These measures ensure the Kalvari class can evade detection by even the most sophisticated anti-submarine warfare assets.

Superior endurance and operational flexibility set them apart from predecessors like the Sindhughosh class. Air-independent propulsion (AIP) systems, based on MESMA technology, extend submerged patrol durations to three weeks without snorkelling, a leap from conventional diesel limits. This allows stealthy loitering in hostile areas, such as the Arabian Sea chokepoints or near the Andaman and Nicobar Islands, amplifying strategic reach.

Weaponry underscores their lethality. Six 533mm torpedo tubes launch heavyweight Black Shark torpedoes, capable of homing on submarine noise at speeds exceeding 50 knots. The submarines also deploy SM-39 Exocet anti-ship missiles in 360-degree salvoes, with ranges up to 180 kilometres, turning them into potent standoff strikers against carrier groups or merchant convoys. Future integration of indigenous Astra missiles could extend land-attack options.

Indigenous content has surged to over 80 per cent in later boats, reflecting India’s Atmanirbhar Bharat initiative. Key systems like the lithium-ion battery packs—slated for Vagsheer—promise doubled endurance over lead-acid predecessors, while DRDO’s Varunastra torpedo adds home-grown punch. Collaborations with Bharat Electronics Limited and Tata Advanced Systems have indigenised periscopes, optronics, and radar systems.

Operationally, the Kalvari class strengthens India’s underwater superiority amid rising Indo-Pacific tensions. Commissioned in 2017, INS Kalvari has already demonstrated prowess in exercises like MILAN and TROPEX, shadowing adversaries undetected. Deployments near the Malacca Strait underscore their role in securing sea lines of communication vital for India’s 90 per cent oil imports.

Kalvari submarines counterbalance China’s expanding undersea fleet, including Type 039A Yuan-class boats operating from Gwadar. They enhance India’s two-ocean strategy, partnering with Quad allies for joint patrols and intelligence sharing. Interoperability with US Virginia-class or Australian Collins-class submarines during Malabar exercises hones collective anti-submarine warfare.

The class’s low observability extends to electronic emissions, with passive optronic masts replacing traditional periscopes for non-penetrating surveillance. Thermal imaging and laser rangefinders provide day-night targeting without betraying position via radar masts. This suite, coupled with automated fire control, enables rapid torpedo or missile salvos under periscope depth.

Crew efficiency benefits from ergonomic design and automation, reducing complement to 32 personnel per boat. simulators at Mazagon Dock ensure rigorous training, while women officers now serve aboard, breaking naval traditions. Such human capital investment sustains long-term operational tempo.

Environmentally adaptive hull forms withstand Indo-Pacific currents, from the warm Bay of Bengal to the colder Arabian Sea depths. Diving to 300 metres, they operate reliably in littoral waters, ideal for choking straits like the Lombok or Sunda. This versatility supports amphibious operations and special forces insertion via swimmer delivery vehicles.

Economically, the program injects vitality into India’s defence industrial base. Over ₹60,000 crore invested has spawned 20,000 jobs and spun off technologies for civilian sectors like offshore energy. Export potential beckons, with interest from the Philippines and Indonesia eyeing Scorpène derivatives.

Looking ahead, Kalvari’s legacy lies in redefining India’s maritime posture. By 2030, a fully operational flotilla will deter aggression, secure exclusive economic zones, and project power from the Gulf of Aden to the South China Sea. These silent hunters not only enhance undersea warfare but symbolise India’s ascent as a net security provider.

These technologies significantly enhance the Indian Navy’s undersea warfare capabilities, ensuring underwater superiority in an era of great power rivalry.

Agencies