Trace the evolution of India's submarine arm from import dependence to indigenous construction. What gaps remain?

In 1976, The Hindu called the Russian-made INS Karanj, a diesel-electric boat that ran on batteries underwater, part of "perhaps the most powerful arm of the Indian Navy" [1]. Fifty years later, a new Karanj has been built in Mumbai. India has moved from buying submarines to building them, but it does not yet design them.

Evolution: From Import to Indigenous Construction

• Import phase: The early fleet was made up of Soviet Foxtrot-class boats bought ready-made. The first Karanj served until 2003 [2].
• Long-term planning: In 1999 the CCS approved a 30-year submarine-building plan, with 12 new boats due by 2012 [3].
• Build-in-India phase: Under Project-75, Mazagon Dock (MDL) built six Scorpenes in collaboration with France's Naval Group [2]. INS Kalvari joined in December 2017 [4] and the sixth boat in January 2025 [5].
• Indigenous technology: DRDO's fuel-cell AIP makes its hydrogen on board. It has passed land-based trials and is due to be fitted to Kalvari-class boats during refits [6].

Import (Soviet Foxtrots) → 1999 plan → Licensed build (P-75, MDL) → Indigenous AIP/design (pending)

Gaps That Remain

• Timeline slippage: By 2016-17, not one boat from the 1999 plan had been inducted [3]. The last Scorpene arrived 13 years after the 2012 target [5].
• Ageing fleet and force-level gap: In 2017-18 the Navy had 14 conventional boats plus one leased, aged 17–31 years. The goal was 18 conventional and 6 nuclear-powered submarines [4]. Old boats spend longer in refit, so fewer are ready to deploy.
• Design dependence: Even DRDO's own AIP needs Naval Group certification before it can be fitted [6]. P-75I is reportedly moving to a German design, which would be a third foreign partner with new training and supply chains [7].
• Endurance limit: AIP is not yet at sea. DRDO's energy modules and the "AIP plug" (the extra hull section that holds the system) are still in development [8]. The Scorpenes in service therefore face the same battery limit described in 1976 [1].

India has moved from buying submarines to building them at home, but its own design capability, timely delivery and underwater endurance are still incomplete. The way forward is a committed indigenous design programme, time-bound AIP fitment and a steady order-book for shipyards. Together these would turn "Make in India" into "Design in India", close the force-level gap flagged by the Standing Committee [4] and secure India's sea-denial role in the Indian Ocean.