Stealth frigates INS Udaygiri, INS Himgiri reflect growing number of new-age warships

Commissioning of two stealth frigates – the INS Udaygiri and INS Himgiri—by the Indian Navy on Tuesday at Vishakapatnam reflects a growing fleet of new-age warships in the country.

The warships are the second and third in a series of seven ships of the INS Nilgiri class—the first to be made with new, faster ship-making technique called the ‘integrated construction’. These ships are modular, ergonomic and have been built within the envisaged timelines.

Fitted with latest weapons, sensors, attack missiles like the BrahMos and air-defence missiles, the Nilgiri class has the ability to stay at sea for longer periods—called ‘blue water’ abilities in Naval Parlance. 

The seven-ships of the Nilgiri class – named Project 17-A – are follow-on to the Shivalik Class of frigates and represent a generational leap. The Naval Warship Design Bureau (WDB) has used indigenous ship design, improved stealth, survivability, and combat capability, along with reduced radar signatures, advanced surveillance radars and electronic warfare suites.

Stealthy, versatile and indigenous

The Nilgiri class displaces about 6,700 tons, are five percent larger than their predecessor Shivalik-class frigates and yet incorporate a sleeker form, with a reduced radar cross section.

They are powered by Combined Diesel or Gas (CODOG) propulsion plants using diesel engines and gas turbines that drive controllable-pitch propellers and are managed through an Integrated Platform Management System (IPMS). This enables higher speeds and improved fuel efficiency.

The weapon suite includes supersonic Surface-to-Surface Missiles, Medium Range Surface-to-Air Missiles, 76 mm MR Gun and a combination of 30 mm and 12.7 mm Close-in Weapon Systems and the anti-submarine and underwater weapon systems.

The weapon suite includes the land-attack version of the Brahmos, medium range surface-to-air missiles, anti-submarine warfare and underwater weapon systems. The navy carried out rigorous sea trials to validate the frigates’ hull, machinery, firefighting, damage control, navigation and communication systems, ensuring they are ready for operational deployment.

A proud testament to self-reliance

The INS Udaygiri has been built by Mazagon Dock Shipbuilders Limited (MDL) Mumbai, while INS Himgiri has been constructed by Garden Reach Shipbuilders & Engineers (GRSE) Kolkata. Both shipyards are owned by the Ministry of Defence.

The two warships commissioned yesterday are the 100^th and 101^st warships designed in-house by the Warship Design Bureau of the Indian Navy, and built in India, reflecting the Navy’s continuous effort to enhance indigenous content and self-reliance. High indigenous content — exceeding 75 per cent — has been achieved through the participation of numerous MSMEs and the procurement of major weapons and sensors from Indian Original Equipment Manufacturers.

The new construction process

The Nilgiri class uses ‘integrated construction’ which entails making various parts of a ship, particularly its hull, superstructure, and internal systems in blocks of 250 tonnes each.

These blocks are built with precision to allow cabling and piping to pass through when two set of blocks are welded together seamlessly. Artificial intelligence provides a ‘sequences’ of putting together a warship, including sourcing of material and production timelines.

Indian ship yards now produce a ship in six years, down from the earlier period of 8-9 years.

The Naval Warship Design Bureau, introduced latest technology, brought in new design-software, used artificial intelligence and modern construction techniques. The design bureau uses a software to predict what would a ship be like. It predicts the turning radius, a ship’s sailing ability and its infra-red signature besides the ability to sustain in water and what sort of power it needs. The equipment, layout of machinery, fluid dynamics are predicted by a software.

Old names revived

keeping with the Navy’s tradition of rechristening new ships after their illustrious predecessors, the new Udaygiri and Himgiri carry forward the proud names of earlier frigates that served the nation for decades.

The modern INS Udaygiri pays tribute to the erstwhile ship of the same name, which was in commission from 1976 to 2007. The INS Himgiri honours the erstwhile ship with the same name that served from 1974 to 2005. The commissioning of the new ships thus links India’s rich maritime heritage with promising future aspirations.

The modern INS Udaygiri’s keel was laid in May 2019 and the ship was launched at sea in May 2022. The modern day INS Himgiri’s keel laid in November 2018 and the ship was launched at sea in December 2020. Both ships underwent a comprehensive schedule of trials in harbour and at sea prior delivery to the Indian Navy.

The balance four ships of the Nilgiri Class --- The Dunagiri, Taragiri, Vindhyagiri and Mahendragiri are at various stages of construction at MDL & GRSE and would be delivered to the Indian Navy by mid-2026.

Growing focus on East

The simultaneous induction of two major combatants highlights the Navy’s growing operational focus on the Eastern coast. Both frigates will join the Eastern Fleet under the Eastern Naval Command, significantly enhancing India’s ability to respond rapidly to maritime contingencies and to secure sea lanes in the Bay of Bengal and beyond.