The Indian Navy is quietly advancing one of the most significant domestic standardisation efforts in underwater warfare.
This strategic shift revolves around designing the upcoming Project-77 nuclear-powered attack submarines (SSNs) and Project-76 next-generation conventional submarines (SSKs) using a shared foundation of core technologies, sensors, and combat systems.
Based on information from defence sources, naval planners have pinpointed several essential technologies that will be common to both submarine fleets.
The primary goal is to boost domestic manufacturing, significantly lower reliance on foreign suppliers over the submarines' operational lifespans, make crew training more straightforward, and establish a unified "National Submarine" framework for future underwater forces.
A Common "Brain" for Future Fleets
A key pillar of this strategy is the creation of a universal, domestically produced Combat Management System (CMS), which will act as the operational nerve centre for both classes of submarines.This flexible CMS architecture is designed to manage various critical tasks, including combining sensor data, tracking targets, controlling weapons, assisting in tactical choices, and managing navigation.
Reports suggest the Navy intends to use identical multi-function displays and operator consoles across both the Project-76 and Project-77 platforms.
This commonality will streamline software updates, ease maintenance, and allow crews to transition between different submarine types more easily.
This approach marks a dramatic shift from India’s past submarine procurement strategies, which often relied on importing distinct combat and support systems from various foreign countries for each new submarine class.
Advanced Masts and Shared Sensors
The Navy is also standardising modern situational awareness tools across both programs.Instead of traditional optical periscopes that penetrate the pressure hull, both submarine classes are expected to utilise advanced, non-penetrating optronic masts created by the Instruments Research and Development Establishment (IRDE).
These modern masts employ high-definition cameras, thermal imaging, and infrared sensors to send vital battlefield information straight to the combat management system via fibre-optic networks.
Furthermore, both the SSNs and SSKs will share communication masts, electronic warfare equipment, and Electronic Support Measures (ESM), ensuring both fleets possess identical capabilities for signal intelligence and situational awareness.
Unified Offensive Capabilities
The offensive weaponry will also see significant standardisation.Both the Project-76 and Project-77 submarines are projected to be armed with the domestically built Varunastra heavyweight torpedo, as well as the upcoming Takshak torpedo.
While the much larger Project-77 nuclear submarines are slated to house a 24-cell Vertical Launch System (VLS) for firing land-attack and hypersonic weapons, the control interfaces for missiles like the Nirbhay cruise missile and the BrahMos-II hypersonic missile will likely remain identical across both submarine types.
This shared design means the conventional Project-76 submarines could potentially fire many of the same advanced weapons from their torpedo tubes or future modular VLS units, adding immense operational flexibility while keeping logistics simple.
Sonar, Stealth, and Propulsion
For underwater detection, both fleets will depend heavily on the Integrated Sonar System (ISS) developed by the Naval Physical and Oceanographic Laboratory (NPOL).This comprehensive system features bow-mounted sonars, flank arrays, towed arrays, and passive intercept systems. To remain undetected, both projects will use locally developed anechoic tiles coating their hulls, which are designed to absorb enemy active sonar waves.
A notable area of technological crossover is in propulsion quietening.
While the Project-77 will be driven by a powerful nuclear reactor and the Project-76 will run on advanced diesel-electric engines with Air Independent Propulsion (AIP), the Navy is exploring the use of a shared pump-jet propulsion system for both.
Pump-jets are significantly quieter than traditional propellers and are considered vital for modern stealth submarines.
Different Roles, Shared Foundations
Naturally, the two programs serve different strategic purposes and vary greatly in scale.Open-source intelligence indicates that the Project-77 SSNs—the first two of which were cleared by the Cabinet Committee on Security in October 2024 for an estimated ₹40,000 crore—will displace nearly 10,000 tonnes and utilise a 190 MW pressurised light-water reactor (CLWR-B2).
In contrast, the Project-76 SSKs, currently in the detailed design phase led by the Defence Research and Development Organisation (DRDO) and the Warship Design Bureau, are expected to remain in the 3,000-tonne class.
Despite these differences, the Navy is determined to share as many subsystems as possible.
From combat architecture and sonar to batteries, acoustic management technologies, and hull materials—such as the high-tensile steel supplied by MIDHANI—the focus remains firmly on commonality.
Defence sources highlight that this unified approach is specifically designed to keep India out of what planners call the “Chakra trap”—a situation where long-term reliance on imported foreign systems leads to critical vulnerabilities in maintenance, spare parts, and future upgrades.
