Adding teeth to the Indian Navy's underwater capabilities, the third Scorpene class stealth submarine, Karanj, will join the fleet on Wednesday at Mumbai

"INS Karanj will be commissioned tomorrow after successful completion of sea trials for over two years. Submarine was undergoing multiple levels of sea trials to validate her capabilities since January 2018," a senior naval officer said on Tuesday.

INS Karanj will be the third of the six Scorpene class submarines with superior stealth and combat capabilities. First submarine of the class named INS Kalvari was commissioned in December 2017 and INS Khanderi joined Indian Navy fleet in September 2019. While Karanj is joining on Wednesday, the fourth and fifth submarines—INS Vela and INS Vagir—are undergoing sea trials. The INS Vagsheer, the last of its class, is under construction.

In 2006, an agreement was signed to build six Scorpene class submarines in India between the French firm Naval Group, formerly known as DCNS, and Mazagon Dock Limited under Indian Navy’s $3.75 billion Project-75 program. The first submarine was scheduled to be delivered by 2012, but the project witnessed repeated delays. Originally, the entire project was expected to be completed by 2020.

But the Navy’s fleet of attack submarines, all diesel-powered, has come down from 21 in the 1980s to just 15 at present. While China operates 65 submarines, Indian Navy has close to eight battle-ready submarines at any given time, as half of its fleet undergoes mid-life upgrades.

Despite having a large coastline of 7,516 km, India’s underwater capability is nowhere close to its needs. As per Indian Navy's 30-year submarine-building plan, approved soon after Kargil conflict, it requires at least 24 submarines. The original plan was to induct 12 diesel submarines by 2012 and another 12 submarines by 2030, but repeated delays forced the Navy to rejig the plan.

The next program is to build six submarines with better sensors and weapons and an air-independent propulsion (AIP) system under Project-75 India (Project-75I). But it is moving at snail's pace. Moreover, in 2019, the Narendra Modi government gave its go-ahead to build six nuclear-powered attack submarines, costing an estimated Rs 90,000 crore, as an answer to Beijing’s naval might.

Meanwhile, DRDO on Tuesday announced that it had achieved an important milestone in the development of air-independent propulsion (AIP) system by proving the land-based prototype of its indigenous system. The AIP system is being developed by Naval Materials Research Laboratory (NMRL) of DRDO. AIP has a force multiplier effect on lethality of a diesel-electric submarine as it enhances the submerged endurance of the boat manifold.

"While there are different types of AIP systems being pursued internationally, fuel cell-based AIP of NMRL is unique as the hydrogen is generated onboard," a DRDO official said, adding that fuel cell-based AIP has merits in performance compared with other technologies.

The technology has been successfully developed with the support of industry partners L&T and Thermax. It has now reached the stage of maturity for fitment into target vessels.