The Indian Navy’s (IN) current concept of evaluating combat power in the ‘number of platforms’ has shifted to ‘capability’ based combat power. Thus their perspective plans are now tilted towards this concept. The IN’s 30 years submarine construction plan launched in 1999 has not proceeded as anticipated. The Maritime Capability Perspective Plan (MCPP) launched in 2012, envisages at least 18 conventional submarines as compared to 24 in 1997. However the completion of the Kalvari Class project and the final approval to build six additional diesel-electric submarines with Air Independent Propulsion (AIP) under Project 75 (India), when given will leverage towards filling the chasm in the existing and future capability based combat power.

Current Force Level

Kalvari Class. INS Kalvari is the first of the six Scorpene class submarines built under Project 75 which was commissioned on December 14, 2017. The second submarine under this class INS Khanderi was commissioned on September 28, 2019. The Kalvari-class is reported to be armed with French-made Exocet SM39 anti-ship missile; a sea-skimming, subsonic, solidfuelled anti-ship missile with an estimated operational range of 50 to 70 km and heavyweight torpedoes. Each submarine can carry up to 18 anti-ship missiles or heavy-weight torpedoes. At present Karanj and Vela are under construction. The fifth submarine is named INS Vagir and the sixth INS Vagsheer. The final delivery of the remaining submarines is planned by 2022.

Sindhughosh Class. Sindhughosh class submarines are the Kilo class diesel-electric submarines. They are designated 877EKM, and were built under a contract between Rosvooruzhenie and the India’s Ministry of Defence. There are nine submarines in this class, commissioned between April 1986 to July 2000.

Shishumar Class. Shishumar class vessels (Type 1500) are diesel-electric submarines developed by the German yard Howaldtswerke-Deutsche Werft (HDW). The first two of these vessels were built by HDW at Kiel, while the remainder have been built at Mazagon Dock Limited, Mumbai. The submarines were commissioned between 1986 and 1994. There are a total of four Shishumar submarines.

The current force level of conventional submarines is 15 with the oldest being more than three decades old and the latest has been commissioned this year. Some older submarines may retire by the time all the Kalvari class submarines are commissioned in 2022 thus the void of force level may still exist.

Life Extension and Refit

To overcome the voids in combat capability, the IN has resorted to upgrading six of its submarines-four of Sindhughosh class and two of Shishumar class under a Major Refit and Life Certification (MRLC) programme.

Shishumar Class. Germany’s ThyssenKrupp Marine Systems (TKMS) has been contracted by Mazagon Docks to upgrade two Shishumar-class submarines for 410 crore (about $0.05 billion) contract. TKMS is also retrofitting anti-ship Boeing’s Harpoon Missiles on these submarines. The upgrade is expected to be completed by 2021.

Sindhughosh class. In July 2018, Russia’s shipbuilder Zvezdochka and Larsen and Toubro announced their partnership on an upgrade of four the Sindhughoshclass class submarines at a cost of about ,5000 crore ($ 0.7 billion) which includes extension of like and fitting them with Klub land attack cruise missile.

Submarine Force Accretion-Project 75(I)

Approval of DAC. The Defence Acquisition Council (DAC), approved on January 31, 2019, the construction of six diesel-electric submarines with AIP at a cost of over 45,000 crore (about $6.3 billion). This is the second project under the MoD’s ambitious Strategic Partnership (SP) model that aims at providing a significant fillip to the Government’s ‘Make in India’ programme.

Expression of Interest for six P75(I) Submarines. As a major initiative towards ‘Make in India’, the Government immediately on taking over after the election, issued the Expression of Interest (EOI) for shortlisting of potential Indian Strategic Partners (SPs) for “Construction of six Conventional Submarines” for P75(I) Project of the Indian Navy on June 20, 2019. The project cost is about 45,000 crore. This is the second project being undertaken under the latest Strategic Partnership (SP) Model, with the first being the procurement of 111 Naval Utility Helicopters (NUH). This would provide a major boost to the indigenous design and construction capability of submarines in India, in addition to bringing in the latest submarine design and technologies as part of the project. The EOI for shortlisting of Indian SPs has been uploaded on MoD and Indian Navy websites. The EOI for shortlisting of OEMs was to be issued in two weeks. The SPs in collaboration with OEMs have been mandated to set up dedicated manufacturing lines for these submarines in India and make India the global hub for submarine design and production. All six submarines under this project will be built in India by the selected Indian SP in collaboration with the selected OEM. In addition, IN would have the option to manufacture six additional submarines under the project. The project would not only aid in boosting the core submarine/ship building industry but would also greatly enhance manufacturing/industrial sector, especially the MSMEs by development of an industrial eco-system for manufacture of associated spares/systems/equipment related to submarines. The potential SPs are expected to respond to the EOI within two months. The Indian companies would be shortlisted based on their capability for integration of system of systems, expertise in shipbuilding domain and the financial strength. The OEMs would be shortlisted primarily based on their submarine design meeting the IN’s Qualitative Requirements and qualifying the Transfer of Technology and Indigenous Content criteria. The overall aim would be to progressively build indigenous capabilities in the private sector to design, develop and manufacture complex weapon systems for the future needs of the Armed Forces. This will be an important step towards meeting broader national objectives, encouraging self-reliance and aligning the defence sector with the ‘Make in India’ initiative of the Government.

Media reported that three Indian shipyards- L&T, Mazagon Docks Shipbuilders Limited and Hindustan Shipyard Limitedare expected to respond to the EOI. The Indian companies would be shortlisted based on their capability for integration of system of systems, expertise in shipbuilding domain and the financial strength. The next step would be to issue the Request for Proposal to the shortlisted companies. Four leading foreign manufacturers of submarine i.e. France’s Naval Group, Sweden’s Saab, Russia’s Rubin Design Bureau and Germany’s ThyssenKrupp Marine Systems are expected to respond to this EOI. The manufacturers would be shortlisted based on their submarine design meeting the navy’s requirements and qualifying the Transfer of Technology and Indigenous Content criteria. However no further details have been released.

Project Details. It is understood the six next generation diesel submarines will have AIP to allow them to stay submerged for longer periods. The submarines will be armed with both BrahMos (for the sea and land targets) and tube-launched torpedoes for anti-submarine warfare. A minimum of 30 per cent offsets are expected based on the current defense offsets policy mandates.

Role of conventional submarines

Submarine as a Platform. An effective submarine should have features of stealth, high mobility, precise targeting systems, minimum logistical requirements and operational autonomy. Submarines can lurk in deep waters silently and covertly to strike key targets with precision missiles by surprise; or to deploy ground forces and provide support. In certain dangerous situations it may be the only survivable platform.

Sea Control. The exercise of sea control and sea denial to adversaries are fundamental missions of the submarine. Surface platforms are highly endangered by submarines.

Precision Strike. Long periods of silent presence in a particular area is required in order to observe, identify and destroy vital targets.

Coastal Defence. Submarines which can operate in the littorals can provide effective coastal defence. Diesel-electric submarines are ideally suited for this shortranged mission. Germany is a global leader in designing small, stealthy submarines that can effectively patrol littoral waters at a fraction of the cost of nuclear-powered submarines as they use hydrogen fuel cells for power, which allow submarines to operate nearly silently for weeks at a time without using expensive nuclear reactors.

Insertion and Extraction of Special Forces. Submarines which can operate in the littorals are well suited for this role.

Coordinated Fire Support. Submarines which can operate close to the littorals should be able to provide coordinated fire support in support of forces both ashore and afloat.

Intelligence Collection. By covert surveillance a submarine can gather tactical and strategical intelligence.

Theatre Anti-submarine Warfare. This is aimed for the protection of the sealift, both in littoral areas and in the open ocean, as well as strategic anti-submarine warfare operations and monitoring adversaries activities.

Anti-surface Warfare. Capable of attacking merchant and military targets and should be able to destroy small, shallow-draft vessels.

Mine Operations. To lay mines covertly and disabling hostile submarines is a key method of sea control.

Future Technologies for Submarines

Stealth. Stealth is the key factor of submarine naval warfare which enhances the ability to operate anywhere, at any time, covertly as a tactical and strategic deterrent. A submarine’s ability to avoid detection is defined in terms of its acoustic signature. There are many sources contributing to a submarines acoustic signature like machinery and other propulsion-related vibrations enter the water through the hull and radiate in all directions. Each type of noise has a unique pattern, which can differ with speed, depth, and water conditions. Stealth technologies continue to improve and are increasingly available to retrofit older submarines. Hull coatings, improved propeller design, and quieted propulsion plant equipment reduce the submarines overall noise levels, especially at high speeds. Incorporation of AIP, advanced technology based batteries and improved quieting measures will reduce the submarines vulnerability to acoustic detection to even a greater degree. In littoral regions, nonacoustic signatures will become increasingly important. A submarine exhibits various non-acoustic signatures, some of which are highly dependent on the submarines speed or depth. The main one is the magnetic and electrical fields generated as a result of the materials used in the construction of the submarine. Systems are currently available to reduce a submarine’s magnetic and electrical signatures. Other non-acoustic signatures include the submarines wake, contamination within the wake from bubbles or chemicals, radar reflectivity and the heat generated by the submarines propulsion plant.

Improved Battery Technology. Earlier submarine batteries allowed submerged operations at slow speed for about 12 hours. The modern battery designs allow the submarine to remain submerged for about three to four days. Advanced submarine battery designs are under development worldwide and could increase endurance up to 10 to 12 days of submerged operations.

Air Independent Propulsion (AIP). AIP is a technological break-through for conventional submarines as the diesel-run energy generator requires exterior air for combustion of the conventional submarine but those with an AIP system use energy sources that do not require surface air as they use fuel cells. This allows them to be submerged without being detected for much longer than diesel electrical submarines. The fuel cell allows the submarine to generate the energy it needs from hydrogen and oxygen. However, hydrogen generation system needs very large storage space which effects the submarine’s weight and storage space thus submarines with AIP need to be larger in size. To solve this problem, SENER has partnered with ThyssenKrupp Marine Systems to develop an AIP based on the methanol reforming process, which allows the hydrogen required to feed the fuel cell to be produced on board.

Sensors. Rapid developments in computer and signal processing has resulted in increasingly capable sensor suites and tactical information systems with more automated functions, making it easier to detect, classify and engage targets successfully with fewer operators. Future sonar suites include advances such as flank arrays, towed passive sonar arrays, real-time selfnoise monitoring, and advanced signal processing capabilities. A low-end diesel submarine is likely to have a system equivalent to the present KILO SS class sonar suite, which has a capable array integrated to simple processors. With enhanced signal processing and displays coupled to the existing array, a low-end diesel submarine could become Anti-Submarine Warfare (ASW) capable. Several nations have shown an interest in submarine-mounted non-acoustic ASW systems to complement their acoustic sensors. Such systems may be available in the future.

Weapons. Torpedoes increasingly have greater destructive power. Eight major producers offer at least 21 models of submarine-launched torpedoes for export. The spectrum of torpedo systems and technologies spans from simple straightrunning weapons to wake-homing and sophisticated acoustic homing torpedoes. Modern submarine-launched heavyweight torpedoes can literally break some warships in half. The proliferation of relatively inexpensive wake-homing torpedoes has put “fire and forget” weapons, which are highly lethal and difficult to counter. Some examples are the Black Shark of Whitehead Alenia Sistemi Subacquei (WASS), F21 heavyweight torpedo from Naval Group, Spearfish advanced heavy weight torpedo from BAE Systems, DM2A4 Seehecht from Atlas Elektronik, Mk48 ADCAP Mod 7 Common Broadband Advanced Sonar System (CBASS) developed by Lockheed Martin, MK 54 built by Raytheon and many more.

Cruise Missiles. Russia, France and the US market submarine-launched anti-ship cruise missiles. Modern anti-ship cruise missiles can be difficult to detect and allow little reaction time. China has developed YJ-18 (NATO designation CH-SS-NX-13[5]) in 2015 and it is in service since then. Future technologies that will be incorporated into cruise missiles include improved stealth, guidance systems, seekers, digital processing, and high-performance propulsion systems.

Anti-submarine Cruise Missile. Russia is currently the only country that possesses a submarine launched anti-submarine cruise missile capability. However, China has expressed an interest in developing its own submarine launched ASW missile and may seek Russian help.

Off-board Vehicles. Off-board UUVs and UAVs deployed by submarines will extend the battle space and enhance sensing capability while reducing risk to the submarine and its crew. They will also improve the effectiveness of forward-deployed submarine forces. Advance technology and design are required for compact energy source, sensor, and handling requirements. Submarine wide-band high-data-rate communication with off-board vehicles will be essential for integrated force employment.

S-80 Plus: Most Capable and Revolutionary Submarine

Spain, like India, is a country with a huge maritime tradition. All Spanish Navy submarines have been built by Navantia, a state-owned company, who currently is in charge of the design and construction of four non-nuclear attack submarines for the Spanish Navy, the S-80 plus.

Previously, Navantia was co-designer and builder of Scorpene class submarines for the Chilean and Malaysian navies, and also participated in the design and transfer of technology of India’s six Scorpene submarines, built in MDL (Mumbai), deploying a resident team to India between 2006 and 2013.

The S-80 plus submarine is an oceanic high-range 3,000 tonne non-nuclear submarine enhanced with anaerobic Air Independent Propulsion (AIP). The submarine design has been made by Navantia with the support of Electric Boat, the primary builder of submarines for the United States Navy for more than 100 years. The AIP system has been developed by Collins Aerospace, which is also a major supplier to international NASA space programmes, Tecnicas Reunidas and Abengoa of Spain.

The S-80 plus submarines will have performance in ocean-going force projection and “blue water” warfare scenarios only available in current nuclear-powered attack submarine (SSN), including a threeweek anaerobic range and the ability to fire submerged land-attack cruise missiles. This new concept in a conventional Submarine brings an excellent capability in covert operations and first strike. In particular it excels in stealth and littoral water performance, including bottoming and discrete transit and insertion in negated waters.

The S-80 plus features a leading-edge AIP system based on a Bio-Ethanol processor, therefore avoiding exotic or highly processed consumables. Bio-Ethanol availability is immediate at almost any country, while medical grade Liquid Oxygen is a common supply for Hospitals. The output of the bio-Ethanol reactor feeds a series of state-of-the-art fuel cells developed specifically for this project.

The S-80 plus construction programme progresses smoothly. The first unit will be afloat in October 2020, entering into service in 2022. The design is nowadays being proposed for international programmes in Holland and India.

Once in operation, the S-80 plus will be the most capable and revolutionary submarine of its class.