Delay hits Scorpene retrofit to boost stealth, endurance

NEW DELHI: India has once again missed the boat to enhance the underwater operational endurance and stealth of its latest Scorpene or Kalvari-class conventional submarines, with the already delayed air independent propulsion (AIP) system developed by DRDO still not ready for integration with the vessels.

The first Scorpene submarine to be built at the Mazagon Docks (MDL) with French collaboration, INS Kalvari, which was commissioned in Dec 2017, will now complete her ongoing maintenance refit at the Mumbai naval dockyard without being retrofitted with the AIP plug as was originally planned, defence ministry sources told TOI.

"The fuel cell-based AIP system developed by DRDO's Naval Materials Research Lab, which has L&T as the prime industry partner, is still not yet operationally available. Hopefully, it should be ready by the time the second Scorpene (INS Khanderi) comes for her scheduled normal maintenance refit in mid-2026," a source said.

The Navy after a long delay has inducted six diesel-electric Scorpene submarines, constructed by MDL in collaboration with the French Naval Group under Project-75 for over Rs 23,000 crore, with the sixth INS Vagsheer being commissioned in Jan this year.

There is major concern about the continuing delay in the indigenous AIP project, which was originally slated for completion by June 2017 after being sanctioned in 2014 at an initial cost of Rs 270 crore.

Amid the delay, MDL and Naval Group signed an agreement for the integration of the indigenous AIP energy system plugs on the Scorpenes only on July 23. Under it, each submarine will undergo a complex project called "jumboisation", involving precision cutting of the hull, safe insertion of the AIP plug and then rejoining the structure to ensure the vessel is fully operational again.

Unlike nuclear-powered submarines, which have unlimited underwater endurance, diesel-electric boats must surface or snorkel every couple of days to get oxygen to recharge their batteries. Those fitted with AIP, however, can stay submerged for around two weeks to significantly boost their stealth and combat capabilities.

With Pakistan on course to induct eight Yuan or Hangor-class conventional submarines with AIP from China in a major capability jump, India's depleting conventional underwater combat arm has become a major worry. China, of course, now has the world's largest navy, which includes over 50 diesel-electric and 10 nuclear submarines.

Apart from the six French-origin Scorpenes, India has seven very old Russian Kilo-class and four German HDW diesel-electric submarines at present. It also has two operational SSBNs (nuclear-powered submarines armed with nuclear ballistic missiles) in INS Arihant and INS Arighaat, with the third to be commissioned as INS Aridhaman this year, as reported by TOI earlier.

The long-pending projects to build three additional Scorpenes for Rs 38,000 crore and six new-generation diesel-electric submarines, with both AIP and land-attack cruise missiles, for Rs 70,000 crore under Project-75-India at MDL, are also yet to be finalised and inked.