India's twin submarine dilemma

Two crucial pieces of the puzzle — a nuclear-powered attack submarine and an indigenously designed and built conventional submarine — have been missing from the Indian Navy's force structure.

In Short

• Project 77 nuclear-powered attack submarine cleared, first to serve by mid-2030s
• SSNs offer unlimited range, high speed, and multi-role capabilities
• Funding, resource challenges have affected indigenous submarine projects

Two crucial indigenous submarine programmes, to build a conventional diesel-electric submarine and a nuclear-powered attack submarine, will decide the trajectory of India’s maritime power in the 21st century.

Project 76 will build six large diesel-electric conventional submarines (SSKs) to an indigenous design. This is a crucial capability because, despite operating submarines for close to 60 years, India has never designed and built its own submarines.

Even more significant is the Project 77 nuclear-powered attack submarine (SSN), cleared by the Cabinet Committee on Security in 2024. The first P-77 SSN will enter service in the mid-2030s.

STRATEGIC IMPORTANCE OF SSNs

SSNs are powered by nuclear reactors and travel at twice the speed of SSKs. Because they are nuclear-powered, they have unlimited range and their endurance is limited only by the endurance of crew and food supplies.

SSNs carry heavy missiles and torpedo loads and are the only naval platforms that can simultaneously perform multiple tasks as single units — operate in heavily defended enemy waters, chase and hunt large enemy platforms like aircraft carriers and destroy targets on land.

All five permanent members of the UN Security Council operate SSNs, the US alone operating more SSNs than the rest of the world put together.

India leased two SSNs over the past four decades, first from the Soviet Union, and later from the Russian Federation. A third unit is fitting out in a Russian shipyard due for transfer to India later this decade.

But in a world where dependencies are swiftly turned into leverage, big powers cannot rely on borrowed military power. It is now also a world where satellite constellations and long-range drones and missiles have strengthened shore-based defences and increased the vulnerability of surface assets and naval fleets. These are challenges which submarines do not face yet, as they hide under the sea.

Attack submarines, both conventional and nuclear, could be the trump card for India to cope with China's rising maritime power. China already has the world's largest navy in numbers – 370 ships and submarines, which could grow to over 400 vessels.

INDIA'S SUBMARINE GAP

Yet, India has been slow to acquire submarine capabilities. On the face of it, India fields the most impressive Indian Ocean region (IOR) navy and is one of a handful of countries to build its own aircraft carrier, frigates and destroyers.

Two crucial pieces of the puzzle — a nuclear-powered attack submarine and an indigenously designed and built conventional submarine — have been missing from its force structure.

Reasons range from a lack of clarity, inadequate planning and resource allocation and the inability to leverage lessons learnt from building its own nuclear-powered ballistic missile submarines (SSBNs).

India’s four Arihant class SSBNs displace over 6,000 tons and combine all of India’s greatest strategic technological breakthroughs of the past 60 years — nuclear-powered reactors, and long-range ballistic missiles tipped with nuclear weapons.

Close to 80 per cent of these submarines are built using equipment sourced from 500 local industries. But since these submarines are strategic platforms and not conventional war-fighting units, they are kept in a secretive silo, with few details shared. Hence, it can be argued that India was unable to leverage its SSBN industrial ecosystem into building conventional submarines.

This was despite internal studies showing a 60 to 70 per cent equipment commonality between conventional and nuclear boats, and 100 per cent commonality in onboard systems like high-pressure air compressors, hatches, fire-fighting, hydraulics, diving and surfacing control systems.

India developed its own combat management systems, sonars, pumps, auxiliary power units, periscopes, and most importantly indigenous steel for submarines. But this ecosystem was not leveraged for conventional submarine building. India relied on French, German and Russian imports for its SSKs.

And this led to a conundrum — a country that built among the most complex military projects hasn’t designed and built its own conventional submarines.

DELAYS & COMPETING PRIORITIES

South Korea, a country which bought German SSKs similar to India in the 1980s, offered the Indian Navy an advanced version of the same submarine in 2019. Seoul doubled down on absorbing technology and pursuing spiral development. India, meanwhile, pursued the ‘transfer of technology’ mirage from fickle European partners.

It wasn't meant to be this way.

The Indian Navy took an ambitious leap towards submarine building in 1999 — its 30-year submarine building plan called for indigenously building 24 SSKs and 6 SSNs by 2030. So far, only 6 SSKs and no SSNs have been built.

Astonishingly, for such a potent platform, the SSN project appeared to have been a low-priority item through the early 2000s. The defence ministry cleared the need for six SSNs in 2015, but it took nine years to order the first two boats. Cost might have been a factor – each SSN costs around Rs 20,000 crore.

The Navy’s Submarine Design Group (SDG) is designing Project 77 SSN, with the first boat due to start construction in the late 2020s and to enter service in the late 2030s.

From a modest-sized SSN of around 6000 tons, its designers have bumped the P 77 SSN up into a large submarine with a dived displacement of around 10,000 tonnes. This would make the P 77 roughly the size of the Akula class SSNs leased from Russia by India. The submarine will have a lot in common with the S-5 SSBN currently being built in Visakhapatnam, including the 190 MW reactor.

The SSN will be equipped with vertically launched tubes for conventional hypersonic missiles, which means it will be an SSGN – a conventional missile carrying submarine – rather than a plain SSN.

The Advanced Technology Vessel (ATV) Project, which built the Arihant and S-5 class SSBNs and the P-77 SSNs, will also design and build the Project 76 SSK. The SDG and ATVP plan to complete the design of this 3,000-tonne submarine by 2028.

But challenges loom on the horizon.

India is set to sign a contract worth approximately Rs 100,000 crore with Germany’s TKMS to buy six 3000-ton SSKs, equipped with Air Independent Propulsion (AIP) and cruise missiles, at the Mazagon Docks. Construction is expected to begin in the late 2020s with the first of the class entering service only in the mid-2030s. Naval officials say Project 76 will be ordered only after the P-75(I) buy goes through.

But with finite defence budgets and competing priorities, it will be a challenge to fund two parallel conventional submarine projects. India’s wait for a truly indigenous submarine project leveraging proven expertise could get even longer.

- Ends