India to Build 3 More Kalvari-Class Submarines with DRDO AIP Tech in ₹38,000 Cr Deal with MDL

India is all set to significantly boost its underwater naval power with a major new deal worth ₹38,000 crore. Mazagon Dock Shipbuilders Limited (MDL), based in Mumbai, is preparing to sign a landmark agreement in June 2025 for the construction of three new Kalvari-class submarines for the Indian Navy. These submarines will not only be more advanced than their predecessors but will also showcase a leap in indigenous defence technology and self-reliance.

The Kalvari-class submarines are part of the Indian Navy’s ongoing effort to modernise its ageing underwater fleet. Derived from the French Scorpene-class design and developed in partnership with France’s Naval Group, these diesel-electric attack submarines are known for their stealth, agility, and powerful weapon systems. The Indian Navy currently operates five Kalvari-class submarines, with the sixth—INS Vagsheer—commissioned earlier this year on January 15, 2025.

What makes the upcoming trio of submarines stand out is the integration of an indigenously developed Air Independent Propulsion (AIP) system, designed by the Defence Research and Development Organisation (DRDO). This system, based on fuel-cell technology, eliminates the need to surface frequently for oxygen, allowing submarines to remain submerged for extended periods—up to 14 to 21 days—compared to just 48 hours without AIP. This significantly increases stealth and mission duration, making the vessels ideal for deep-sea and covert operations.

Unlike the first six Kalvari-class submarines that will receive AIP retrofits during their mid-life upgrades—starting with INS Kalvari in September 2025—these new submarines will be equipped with the AIP system from the outset. This reduces downtime and enhances readiness.

The new submarines will also feature major technological upgrades. They will carry improved electronics, next-generation communication systems, advanced navigation tools, and a combat management system developed by Bharat Electronics Limited (BEL). Additionally, they will be fitted with lithium-ion batteries, offering more energy efficiency and longer submerged operations.

One of the standout elements of this project is its emphasis on indigenisation. At least 60% of the submarine components will be sourced from Indian companies, including many micro, small, and medium enterprises (MSMEs). This not only strengthens domestic defence capabilities but also generates employment and encourages technology transfer across the Indian industrial sector.

The submarines will be larger and more capable than the earlier Kalvari-class models, potentially similar in size to Brazil’s Riachuelo-class submarines. Their extended range and endurance could allow them to patrol areas as far as the waters around Australia, marking a strategic advantage in the wider Indo-Pacific region.

The importance of these submarines comes into sharper focus as some of the Indian Navy’s older Russian-origin Kilo-class submarines near the end of their operational life. With increasing maritime competition in the Indian Ocean—especially from regional rivals—India is determined to maintain a credible underwater deterrent and protect its maritime interests.

The contract is the result of detailed negotiations between MDL and the Ministry of Defence. The project received its initial clearance from the Cabinet Committee on Security in early 2025. A symbolic agreement was expected during Prime Minister Narendra Modi’s visit to France in February 2025, with the final signing slated for this month.

Construction of the first submarine is expected to begin around 18 months after the contract is signed, with MDL targeting delivery within six years—by 2030. This marks a significant improvement over the decade-long timeline taken for earlier submarines, reflecting MDL’s growing shipbuilding capabilities and streamlined production methods.

In sum, this ₹38,000 crore submarine deal is not just about adding three more vessels to India’s fleet. It’s a forward-looking step towards defence innovation, regional dominance, and a stronger, self-reliant India at sea.