The Indian Navy is quietly driving a massive internal standardisation initiative for its future underwater fleet.
This strategic transition focuses on developing the upcoming Project-77 (P-77) nuclear-powered attack submarines (SSNs) and Project-76 (P-76) diesel-electric conventional submarines (SSKs) using a single, shared baseline of essential technologies, combat architectures, and sensor suites.
Naval strategists have identified a core list of vital technologies that will be outfitted across both classes of vessels.
The primary objective is to accelerate local manufacturing, drastically reduce the dependence on foreign suppliers, simplify the training of submarine crews, and build a cohesive "National Submarine" ecosystem for all future naval platforms.
A Unified "Brain" for Next-Generation Submarines
Central to this new design philosophy is the development of a fully indigenous Combat Management System (CMS), which will serve as the universal digital brain for both fleets.This adaptable CMS framework will handle critical operational duties, ranging from fusing sensor inputs and tracking enemy targets to weapon engagement and navigation control.
According to reports, the Navy plans to deploy the exact same multi-function displays and crew consoles in both the P-76 and P-77 submarines.
Sharing the same hardware and software will make future digital upgrades seamless, reduce maintenance overhead, and allow sailors to switch between different submarine classes without needing extensive retraining.
This unified strategy is a sharp departure from historical procurement practices, where India historically imported completely different combat and support systems for each class of submarine from various countries.
Modern Sensors and Shared Optronic Masts
The Indian Navy is also harmonising its modern surveillance and situational awareness hardware across both submarine programs.Rather than relying on older optical periscopes that require penetrating the pressure hull, both fleets are slated to use cutting-edge, non-penetrating optronic masts designed by the Instruments Research and Development Establishment (IRDE).
These advanced masts will feature high-definition video, thermal imaging, and infrared sensors, transmitting real-time battlefield data directly to the CMS through fibre-optic cables.
In addition, the SSNs and SSKs will feature identical communication masts, Electronic Support Measures (ESM), and electronic warfare suites, guaranteeing that both submarine classes have the exact same signal intelligence and threat-detection capabilities.
Standardised Offensive Firepower
Weapon systems are another major area slated for standardisation. Both submarine classes are expected to carry the indigenous Varunastra heavyweight torpedo and the developmental Takshak torpedo for underwater engagements.While the significantly larger P-77 nuclear submarines will feature a 24-cell Vertical Launch System (VLS) specifically for firing long-range land-attack and hypersonic missiles, the actual user interfaces and software required to launch weapons like the Nirbhay and BrahMos-II missiles will be the same across both platforms.
This modular approach means that the conventional P-76 submarines could also theoretically launch similar advanced munitions from their standard torpedo tubes or potential modular VLS sections, greatly expanding their tactical flexibility while streamlining the supply chain for ordnance.
Sonar, Stealth Technologies, and Propulsion
To detect enemy vessels, both future fleets will rely heavily on an Integrated Sonar System (ISS) engineered by the Naval Physical and Oceanographic Laboratory (NPOL).This comprehensive detection suite includes bow-mounted active sonars, flank arrays, towed arrays, and passive interception tools.
To evade detection, both submarines will be covered in domestically manufactured anechoic tiles that absorb incoming active sonar pings.
A highly significant crossover is also expected in propulsion quieting technologies.
Although the P-77 will be powered by a nuclear reactor and the P-76 will utilise advanced diesel-electric generators paired with Air Independent Propulsion (AIP) and indigenous lithium-ion batteries, the Navy is actively researching the use of a common pump-jet propulsion system for both classes.
Pump-jets are substantially quieter than standard propellers and are increasingly critical for masking the acoustic signature of modern stealth submarines.
Distinct Missions but a Shared Foundation
While they will share many internal systems, the two submarine programs are being built for vastly different strategic roles and physical dimensions.The P-77 SSN project, which saw its first two boats formally cleared by the Cabinet Committee on Security (CCS) on October 9, 2024, for an estimated ₹40,000 crore, will have a displacement of nearly 10,000 tonnes.
It will be powered by a 190-megawatt pressurised light-water reactor (CLWR-B2) developed domestically by the Bhabha Atomic Research Centre (BARC).
Furthermore, open-source reports indicates the P-77 will introduce a manned-unmanned teaming concept, acting as a mothership for large Unmanned Underwater Vehicles (UUVs) like the indigenous JALKAPI-XLUUV to conduct surveillance and anti-submarine missions.
Conversely, the P-76 SSKs, currently undergoing detailed design by the DRDO and the Warship Design Bureau, are targeted for a 3,000-tonne displacement.
The P-76 program aims for up to 95% indigenous content and is envisioned to eventually succeed the older Sindhughosh-class vessels.
Despite the massive gap in size and propulsion, the Navy remains firmly committed to integrating common subsystems wherever feasible.
From the overarching combat architecture and sonar to acoustic management, batteries, and the specialised high-tensile hull steel supplied by MIDHANI, the prevailing theme is absolute commonality.
Defence insiders stress that this standardisation roadmap is specifically engineered to prevent the Navy from falling into the "Chakra trap"—a historical vulnerability where prolonged reliance on foreign hardware created severe bottlenecks in acquiring spare parts, performing maintenance, and executing future system upgrades.
