Far from the public glare and limelight, the navy secures the sea lanes and ensures free flow of maritime traffic using a plethora of procedures, operations, equipment and platforms. Signs of greatness of a navy are reflected by its ability to withstand deployment strains and stresses at far off distances from its shores and the preparedness it maintains to pack a punch with total surprise. For the Indian Navy, the seafaring capability is provided by its surface combatants while an element of stealth in its striking prowess is held by its sub-surface fleet of submarines the pride of which is the recent addition — the nuclear powered INS Arihant.

The moment INS Arihant — the killer of the enemy — was launched into the waters off the Visakhapatnam harbour in the eastern coast on July 26, 2009, India entered a select list of six nations after US, Russia, UK, France and China to design and built a nuclear powered submarine. The occasion coincided with the 10th anniversary of the Kargil War echoing the fact that eternal vigilance is the price of liberty. The vigilance which INS Arihant will maintain after it becomes operational in another two years time will be in the depths of the seas and oceans remaining unnoticed yet holding one the deadliest offensive packs.

Submarines are silent killers, always on the prowl but often stay out of reach of the common detection and attack systems. While on operational deployment submarines remain at specified depths for long periods extended to weeks and months and maintain little contact with the shore except while snorkelling and surfacing out for replenishments. Most submarines hunt for targets with torpedoes and missiles collecting intelligence using sonar and periscope while adopting either diesel-electric or nuclear propulsion.

A conventional submarine (SS) usually powered by diesel motors run on batteries when underneath to maintain silence. When the batteries exhaust these vessels need to surface for recharging and that way reveal their existence. The diesel electric submarines also generate carbon dioxide which periodically needs to be discharged from the boat to maintain safety for which the vessel needs to come out of water.

These are certain limitations of the conventional diesel electric submarine. It makes them vulnerable to attack for which they are not suitable for strategic assignments and deployments. This role of late has gradually been reserved especially for the elusive nuclear powered submarine — an evolution with many of the shortcomings of its diesel propelled cousins removed.

Nuclear powered submarines that way are extraordinary maritime marvels. A navy that possesses it concentrates most of its offensive capability on these vessels for use to alter courses of hostile exchanges. This is a legacy of the cold war era but now has obtained acceptance to the extent that it is now a standard procedure of engagements.

A nuclear powered attack submarine (SSN) equipped with an array of sensors and weapons is designed as a hunter/killer platform used to seek, track and destroy hostile submarines and warships and other maritime assets, carry out attacks on surface targets deep inside the shore, deploy special forces and act as a reconnaissance unit and escort to task forces to pre-empt aggression. These assortment of roles assigned to the SSN is primarily due to its endurance, greater depth and higher speeds generated which the Indian Navy is now preparing to possess by readying INS Arihant for fulfilling its operational obligations and extending it as a part of a nuclear triad.

The nuclear triad is a Army-Air Force-Navy combined three dimensional framework with two segments presently operational. It is formed by land-based nuclear warhead carrying ballistic missiles deployed in fixed silos or on road/rail mobile units and combat aircraft. Its third arm is to retain the last resort offensive capability and is conceptualized for deployment on board nuclear submarines.

This triad is essential for developing a credible nuclear deterrence with no first strike policy but holding back an undetectable retaliatory capability inform of an underwater mobile platform carrying ballistic missiles. The INS Arihant is intended for developing such a capability for which its propulsion holds the key. The propulsion system of the INS Arihant is constituted by a miniaturized 85 MW pressurized water reactor (PWR) using highly enriched uranium as fuel and light water as coolant.

The reactor developed by Bhabha Atomic Research Centre (BARC) allows the 6,000 ton INS Arihant to develop an underwater speed of 24 knots and a surface speed of about 15 knots. The propulsion thus generated is clean, less noisy at optimum speeds and will enable the INS Arihant to stay submerged for long durations, say for months. The inhouse design and fuel processing of the PWR used in the INS Arihant has laid the foundation to built bigger and complex propulsion systems for fitting into subsequent vessels of similar type a total of five is slotted to join the Indian Navy within a decade.

The INS Arihant will mount 95 crew members, 12 vertical lunch tubes to fire the already tested K-15 Sagarika sub-surface ballistic missile with a payload capacity of around 1 ton and a striking range of 750 km, torpedoes, tube launched cruise missiles and may even include the highly rated Indo-Russian Brahmos. The frame of the boat is designed using a special HY-80 steel used for submarine construction while the hull, made at Hazira, Gujarat by L&T in modules and assembled at Visakhapatnam, is made of titanium enabling it to dive to depths of around 500 metres. Innovative rubber acoustic tiles all over the body help to reduce the signature of the submarine which later may be replaced by non-reflective coatings to reduce sonar returns.

These make the INS Arihant stealthy by design and are likely to give nightmares to enemy warships and submarines though nothing about the shape and structure of the vessel has been released yet. As the Russians have been the chief consultants, one of their successful models — the Charlie II must have been adopted for the INS Arihant design. This is a strong possibility due to the fact that the Charlie II which Indian Navy had operated for three years under lease is 102 m long while INS Arihant is 112 m due to the addition of 12 missiles tubes. Both have a 10 m diameter with the Charlie II mounting a 109 MW reactor while the INS Arihant has a 85 MW model.

Over and above its close resemblance to the Russian Charlie II, the INS Arihant incorporates several advanced features acquired from the knowledge of operation and construction of the German HDW 209 1500, houses an network centric combat management system and an assortment of sophisticated communication equipment. The INS Arihant will be commissioned into the Indian Navy after a series of trials called sea and harbour acceptance tests which will be followed by weapons firing to be completed in nearly two years. In this phase several of the shortcomings of the INS Arihant will be removed to a large extent.

Its most noticeable drawback is its submerged speed. At 24 knots it will be slow to escape a counter attack, say from a constituent warship of an enemy battle-group. This speed should ideally be around 30 knots — a limit which will perhaps be attained by the remaining four planned sister boats.

The 750 km range of its primary attack weapon Sagarika makes INS Arihant suitable for tactical deployments though the tubes that hold these missiles can also be used for a longer range weapon like the planned submarine launched Agni III SL. But this design will be available only after another three to four years. Without a missile of over 2,000 km range, INS Arihant will not be able to fulfil the said role of the hidden segment of the nuclear triad.

These shortcomings are likely to be addressed and removed by the time the vessels joins Indian Navy as the most potent weapon system. Even without a declared strategic role, INS Arihant due to the very nature of its design and propulsion elevates the Indian Navy altogether to a different league. The confidence and the capability which INS Arihant has offered to the designers of the country will enable the process to gain momentum to design more superior underwater vessels as swords lurking stealthily in the depths of the seas and oceans always prepared to make the last annihilating attack.

Kandarpa Kumar Sarma