India's maritime security is increasingly being built around a layered fleet of indigenous warship classes, according to a PIB backgrounder released on Monday. The note places the Nilgiri, Sandhayak and Arnala classes at the centre of a wider shift in how the Indian Navy protects trade, coastline and sea lanes.

The backgrounder said the Navy safeguards a coastline of about 11,098 kilometres, an Exclusive Economic Zone of nearly 2.4 million square kilometres and sea lanes that carry close to 90 per cent of India's trade by volume. That scale explains why surface combatants, survey vessels and coastal anti-submarine platforms are being developed together rather than in isolation.

Three layers of capability

The first layer is surface power. Nilgiri-class stealth frigates under Project 17A are designed for high-intensity operations, with reduced radar, thermal and acoustic signatures. The class includes INS Nilgiri, INS Himgiri, INS Taragiri, INS Udaygiri, INS Dunagiri, INS Mahendragiri and the under-construction Vindhyagiri.

The second layer is knowledge of the sea itself. Sandhayak-class survey vessels strengthen hydrographic capability by mapping seabeds, gathering ocean data and producing nautical charts. This supports naval operations, safe merchant navigation and India's Blue Economy ambitions.

The third layer is littoral anti-submarine warfare. Arnala-class shallow water craft are meant to detect and neutralise submarines near the coast, where larger warships cannot operate as effectively. The backgrounder said these platforms also support humanitarian assistance, disaster relief and search-and-rescue missions.

Why the shipbuilding shift matters

The most important thread running through the backgrounder is indigenous design and production. It said the Nilgiri and Sandhayak classes were designed by the Navy's Warship Design Bureau, while the Arnala and Mahe classes are being built by Indian shipyards. Indigenous content is listed at 75 per cent for Project 17A frigates and over 80 per cent for Sandhayak survey vessels.

The Navy also has 64 of 66 ships and submarines on order being built in India. That is a major industrial signal because warship construction creates demand across steel, electronics, weapons integration, sensors, propulsion, ship design and skilled dockyard labour.

The operational value will be tested by maintenance, crew training, sensor performance and the pace at which shipyards can deliver without delay. Still, the direction is clear: India is trying to move from buying naval capability abroad to designing and sustaining more of it at home.

Source: backgrounder dated 13 July 2026, Release ID 2283989.