India's long-standing ambition to field 24 conventional submarines by 2030 is now running years behind schedule, leaving the Indian Navy facing a growing capability gap beneath the waves as older vessels retire faster than replacements can arrive, Economic Times reported.

The challenge highlights the slow pace of submarine procurement and construction, where even approved projects can take a decade or more before operational boats enter service.

The Navy currently operates 16 conventional diesel-electric submarines drawn from the INS Kalvari, INS Sindhughosh and INS Shishumar classes, in addition to three strategic nuclear-powered ballistic missile submarines. However, the force remains well short of the fleet structure envisioned under India's 30-year submarine construction roadmap.

That roadmap was originally approved in 1999 following planning work led by Vice Admiral AK Chatterji and called for the induction of 24 conventional submarines through a combination of foreign collaboration and indigenous construction by 2030. More than two decades later, the objective remains far from being achieved.

The shortfall has widened as four Sindhughosh-class submarines have already left service, including INS Sindhughosh, the lead boat of the class. While six Kalvari-class Scorpene submarines have been commissioned, they have not fully compensated for the retirement of ageing platforms.

The INS Shishumar-class submarines remain operational after undergoing mid-life modernisation, but the vessels average roughly 35 years of age. As additional retirements loom during the coming decade, maintaining force levels will become increasingly difficult.

To prevent a sharp decline in underwater combat strength, India has launched several parallel submarine acquisition and development efforts. These include Project 75I, the indigenous Project 76 program, the nuclear-powered attack submarine initiative under Project 77 and plans to lease another Russian nuclear-powered attack submarine. Collectively, these projects are expected to deliver at least 22 domestically built submarines in the future.

The most immediate conventional submarine initiative is Project 75I, one of the largest naval procurement programs undertaken by India. Valued at approximately ₹70,000 crore, the project is expected to deliver at least six advanced conventional submarines and potentially as many as nine under future expansion plans.

Mazagon Dock Shipbuilders and Germany's Thyssenkrupp Marine Systems have emerged from the technical evaluation phase and discussions have moved towards commercial negotiations. The submarines are expected to be based on the Type-214 design and incorporate air-independent propulsion technology.

Yet even this flagship acquisition will not provide relief quickly. Current planning indicates the first Project 75I submarine is likely to be delivered around seven years after contract signature, with subsequent boats arriving annually thereafter.

India is simultaneously attempting to deepen domestic participation in submarine weapons production. Hyderabad-based VEM Technologies has entered into cooperation arrangements with TKMS for the manufacture of heavyweight torpedoes within India, supporting broader self-reliance objectives in naval warfare systems.

Looking beyond Project 75I, Project 76 is intended to become India's next indigenous conventional submarine family. The proposed design is expected to integrate a modified version of the Defence Research and Development Organisation's air-independent propulsion technology while building upon lessons learned from earlier submarine construction efforts.

Air-independent propulsion has become a critical requirement for modern conventional submarines because it enables underwater endurance of up to several weeks without needing to surface or snorkel. This significantly reduces exposure to hostile aircraft, warships and anti-submarine surveillance networks.

India's existing Kalvari-class fleet is also expected to receive DRDO-developed AIP systems, bringing enhanced stealth and endurance to boats already in service. Future Project 75I and Project 76 submarines are expected to incorporate similar capabilities from the outset.

While conventional submarine projects seek to address immediate operational needs, the Navy is also investing in nuclear-powered attack submarines under Project 77. The government has approved construction of two indigenous nuclear attack submarines at a cost of approximately ₹40,000 crore, marking a major expansion of India's undersea warfare ambitions.

These submarines are expected to provide far greater endurance, speed and operational reach than conventional vessels. However, they remain a long-term capability, with delivery timelines extending into the mid-2030s.

To bridge the capability gap until indigenous nuclear attack submarines arrive, India is also pursuing the lease of another Russian nuclear-powered submarine. Such an arrangement would provide valuable operational experience and strengthen deterrence during the transition period.

India has made more visible progress in its strategic submarine program. INS Aridaman, the third Arihant-class ballistic missile submarine, reinforces the sea-based leg of India's nuclear deterrent and can reportedly carry up to eight K-4 nuclear-capable missiles with a range of 3,500 kilometres. A fourth ballistic missile submarine has already been launched, while a much larger S-5 class remains under development.

These strategic assets strengthen the nuclear triad by ensuring a survivable second-strike capability. However, ballistic missile submarines perform a fundamentally different mission from conventional attack submarines and cannot compensate for shortages in tactical underwater combat platforms.

The urgency of submarine modernisation has also been sharpened by growing underwater competition across the Indian Ocean. China's expanding submarine presence and Pakistan's induction of modern AIP-equipped submarines have increased pressure on India to accelerate fleet renewal and sustain a credible underwater deterrent.

Ultimately, India's submarine strategy rests on a combination of foreign collaboration, indigenous construction and nuclear-powered expansion. The Navy expects Project 75I, Project 76 and Project 77 to form the backbone of future force structure, supported by domestic manufacturing and technology transfer.

The central challenge remains timing. With several programs still navigating procurement, development and construction stages, and with the first new-generation boats still years from entering service, India must ensure that submarine inductions occur quickly enough to offset the retirement of ageing vessels and prevent a prolonged decline in underwater combat capability.

Agencies