Editor’s Note
Bharatshakti readers may recall a set of three articles by Rear Admiral Shrikhande written in 2018-2019 on the vexed and seemingly intractable issues of Indigenous submarines for the Indian Navy. The links to these are given at the end of this article. In those articles, he advocated greater Indian efforts in designing and building conventional submarines with AIP and VLS capabilities, leveraging the commonalities between nuclear submarine construction and conventional boats. He had also opined in favour of reducing the needless “firewalls” that seem to have been created between the two lines and the very high degree of atmanirbharta (self-reliance) achieved over decades in the nuclear submarine programme. In the article, he espouses the induction of a few SSNs based on our own SSBN design and configuration currently built.
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In the first of the three articles I had written on the theme of indigenisation (Refer to links beneath this article), I highlighted that “Fortuitously, those naval leaders and scientists as well as industry partners in the nuclear propulsion programme decided early on that ‘perfect is the enemy of good enough’. They developed reactors that, while not of the potency or unrefuelled endurance of versions in some navies, had the great virtue of being Indian.” Is it time to once again apply this sensible maxim to making a quicker beginning to the construction, induction and operationalisation of the government’s decision to equip the Indian Navy with nuclear attack submarines (SSN)?
As far as can be made out from open sources, the government intends to have six SSNs, of which two have been currently approved. This article proposes that these two should be fast-tracked by adopting one of the currently available Arihant/or follow-on SSBN designs and avoid the chimaera of “perfection” for indigenous hardware. (SSBN is the abbreviation for submarines that carry the nuclear deterrent in the form of ballistic missiles with nuclear warheads that are critical to maintaining the stability of nuclear deterrence; in India’s case, this is the third and vital leg of the nuclear triad)
So, Why Is Perfect The Enemy Of Good Enough?
Speed matters, but not always and not at any cost in terms of money and time. For the Indian Navy’s needs, the speed of construction may be far more critical than the speed of the attack submarine based on reactors that are perhaps yet to be designed and developed. In an incisive analysis, author and journalist Sandeep Unnithan reports that some quarters feel that an SSN has to have a speed of 30 knots, which would require a nuclear reactor in the range of 190MW instead of the 83 MW that the Arihant class SSBNs are reported to have which could propel these boats at around a top speed of 23-24 knots. Let us analyse this a little further:
- Nuclear propulsion is the best form of Air Independent Propulsion (AIP), although it has not always been thought of that way! The ability to remain underwater and not expose itself to surface detection is the most critical combat virtue of a submarine. In a generic sense, this is called stealth. Tactically and operationally, navies think of any exposure of a submarine or even its periscope or air-breathing device (snorkel) required to charge batteries of non-nuclear submarines (SSK) by other means as a ratio of time spent submerged to time exposed to the surface as its “indiscretion rate”. The complex-sounding term is well-chosen. As the proverb goes, discretion is the better part of valour for submarines because it is most useful when prowling and striking largely unseen and desirably, even unheard.
- As pointed out by Unnithan, nuclear-powered subs also have nearly limitless endurance governed by the finite ability to carry food and other supplies and the ability of a crew confined into a relatively small volume, submerged for two months or more. Even the best conventional AIP-equipped boats still have some indiscretion rate. To state the obvious, attempts to reduce indiscretion have been the main area for technological work in the propulsion systems of non-nuclear submarines.
Speed Helps, But Can Also Kill! In an ideal situation, higher speeds enable any missile, aircraft, ship or submarine to hit a target or be near it quickly in readiness to track or hit it as needed. The argument for speed for an SSN is often made in the context of its ability to keep up with a carrier battle/strike group (CBG/CSG). It and some other arguments need to be clarified here:
- Firstly, it is extremely unlikely that a CBG/CSG in transit will sustain high speeds when combat risks, especially from submarines, exist. There are a few reasons for this;
- Accompanying screening ships (mainly for anti-submarine warfare, ASW, and other threats) seriously degrade their ability to detect submarines at speeds above 18-20 knots. The misconception that high speed is an ASW counter-measure is “safe” in peacetime sorties or exercises and, in many cases, of CSG deployment where little actual threat was expected. Wars have shown that ships at high speed and not doing evasive steering, in addition, position themselves for what the enemy submarine calls a “lucky” shot for which astute tactical appreciation is required. It is good to recall that of the 38 aircraft carriers sunk in WW2, 17 were sunk by enemy submarines. The USN’s S/Ms scored 8 hits within this tally, the Germans 6, and Imperial Japanese Navy subs sank three. Preparatory to an attack, either with anti-ship missiles or torpedoes, an SSN, with its relatively higher tactical speeds, could often better position itself for a “lucky” shot than an SSK.
- Secondly, higher speeds for any vehicle, including cars, means greater noise levels and higher fuel consumption (including reactor fuel). For cars, it is engine noise, road noise, wind turbulence and its noise, etc. Likewise, for ships and submarines, the higher the speed, the greater the acoustic, wake, heat and other combinations of signatures. Therefore, unless an SSN is trying to evade an incoming torpedo or is in a great hurry to reach an operational patrol area where the likelihood of en route detection is very low (itself rather unlikely), it is unlikely that the 23-24 knot max speed of an SSN based on the Arihant reactor platform will be such a disadvantage.
- Thirdly, when carriers are in business —and with few exceptions, this is usually within an enemy’s littoral waters for projecting power on land— when they steam at higher speeds much of the time. It is to launch and recover aircraft back on deck, rearm and relaunch. Usually, therefore, they are in a relatively small operational polygon steaming into the wind to launch and recover and steaming away from the wind during intervals. At this time, a few activities are important:
- One, screening ships continue to sail around the carrier at slower speeds, operating their sonars of various types to look for enemy submarines and provide other defensive protection.
- Two, this is supplemented by helicopters, maritime patrol aircraft on ASW and multi-threat duties.
- Third, importantly, here is where the SSNs now figure significantly. They use their relatively higher speeds to get there and then patrol at lower speeds around the polygon in combination with direct and indirect support while remaining submerged to reduce the effectiveness of space and airborne detection. They can, depending on conditions, use their conformal and towed array sonars while remaining at optimum speeds much lower than the wished-for 30 knots in any case. Fourth, along with carriers projecting power on land by hitting targets and flying air combat missions, most SSNs (or SSGN) would also fire their load on land-attack missiles, as determined by that navy’s operational objectives.
This last point Unnithan makes is very important in the context of what the current Arihant and follow-on SSBN design could achieve in its changed avatar as SSN. From information in the media, even Arihant, the first SSBN design, carries a VLS section that is able to launch either 12 SLBMs of shorter range or four of the longer-range missiles (reportedly 3,500 km). One can guess that the shipyards and companies in the public and private sectors that build this line are fully capable of the relatively minor retooling required to fire conventional land-attack and anti-ship missiles from these silos. The smaller dimensions of such conventional missiles may mean that even an Arihant base model SSN could carry more than 12 missiles.
After all, when four of the US Navy’s Ohio-class SSBNs were converted to an SSGN role, their original 24 silos for the Trident D5 SLBM were converted so that each could carry up to seven Tomahawk land-attack missiles. Of the 24 silos, 22 were converted to carry an impressive conventional missile load of 154 missiles, while two tubes were converted for delivery systems for underwater, concealed launch of their marine commandos (the SEALS).
So, What May Need To Be Considered?
In the near -term, it is quite necessary for the Indian Navy fleet to have the benefits of having two or three very indigenous SSNs based on the proven SSBN design. This manufacturing line could be started quite soon and would require minor redesign efforts or changes in reactor and ancillary systems. From an application of simple logical role differences between SSBNs and SSNs, as seen during such role changes of existing designs, the following relatively simpler “mods” may be required:
- For a change over from strategic launch missiles to conventional ones, naturally different fire control systems (FCS) that enable launch of anti-ship and land attack missiles. Fundamentally, SSBNs try their best not to be detected and patrol so that they are optimally positioned to provide deterrence value through a presumed target set that influences an adversary’s mind. SSNs, on the other hand, prowl designated areas looking for targets and tracking them in situations of tension and conflict in order to attack other ships, submarines and land targets, all the while also trying to be as stealthy as possible.
- Any navy’s SSBNs can and perhaps always carry anti-ship and anti-submarine torpedoes. Tactically speaking, they would use them only for self-defence in case their location in wartime is assessed to be compromised due to an adversary’s attempts at strategic offensive ASW (Stefanick, Tom. Strategic Antisubmarine Warfare and Naval Strategy. Mass: Lexington Books, 1987.)
- One may not know the number of torpedoes an SSBN may normally carry, but it would be logical to think that an SSN may need a larger number of such weapons for its role as an attack submarine. Thus, some modifications may be needed to increase the torpedo-carrying capacity. None of these should be daunting in any way considering the tremendous indigenisation percentage and atmanirbharta of the SSBN programme as brought out in Unnithan’s and this author’s articles, to cite a few across the three areas of “float, move and fight,” reiterate that the ATV programme stands out when compared with any other sector for self-reliance in defence.
Concluding Thoughts
Along with consideration of the construction of two or three SSNs based on the basic SSBN powerplant, design, hull and auxiliary configuration (we can think of them as the “good enough” version), design work on purpose-built, higher-speed SSNs could be progressed. As Unnithan points out, these could be of a higher reactor output to generate the higher speeds of “perfect” SSNs that may take several years to design, validate and construct. Besides higher speeds, future reactors could be more like US Navy reactors, which have fuel for life. Or, the effort should be to have a longer reactor life between refuelling. The downstream effects of this are reduced construction times, operating and maintenance costs, and fewer SSNs required for given operational availability requirements of our Navy.
In the ever-evolving maritime warfare environments, submarines will be the key to enabling conditions of sea control and sea denial in conflict for the objectives of strategy; they will also be important for power-projection missions on land with other instruments in war. In peace, submarines are criticised for not contributing to “presence” in the apparent way that surface ships can. However, we could keep in mind two thoughts: the presence of ships sometimes has its limitations. Second, in an oxymoronic way, the “covert presence” of submarines missing from home ports creates a high degree of ambiguity and uncertainty for an adversary, as explained elsewhere by the author. SSNs, in particular, and all submarines in general are often the better instrument for “covert presence”; SSBNs also enhance the stability of nuclear deterrence in peace and conflict by their covert presence on quiet patrol.
Given the above arguments, it would indeed be advantageous for the nation to build two or three “good enough” SSNs on the SSBN platform, even as efforts have begun to build faster and more versatile SSNs in the quest for “perfection.”
Rear Admiral Sudarshan Shrikhande (Retd)
Links to Articles by the author:
- A Framework for the Next 50 Years of the Indian Navy’s Submarine Arm (January 12, 2018); https://bharatshakti.in/a-framework-for-the-next-50-years-of-the-indian-navys-submarine-arm/
- Actualising the Framework for Indigenising Indian Submarines for the Next Fifty Years (March 07, 2018); https://bharatshakti.in/actualising-the-framework-for-indigenising-indian-submarines-for-the-next-fifty-years/
- A Most Significant Project: Why 75 (I) Submarines May Matter Immensely (May 14, 2019); https://bharatshakti.in/a-most-significant-project-why-75-i-submarines-may-matter-immensely/
RADM Shrikhande is a 1979 graduate of the National Defence Academy. His qualifications include a Masters in Weapon and Sonar Engineering from the Soviet Naval War College (1985-88), an MSc from Indian Staff College (1995), an MPhil from the Indian Naval War College and the highest distinction from the US Naval War College (2003). He has submitted his PhD thesis in sea-based nuclear deterrence to Mumbai University. He has commanded three ships and been a defence attaché in Australia and the South Pacific. Ashore has held a variety of operational and training assignments. In flag rank, he was chief of Naval Intelligence, Chief of Staff SNC, Joint HQ staff duties and in the nuclear forces command, Flag Officer Doctrines and Concepts. In retirement since 2016, he teaches at several institutions, including NDC, Staff and War colleges, spanning strategy, operational art, RMA, Peloponnesian War, Indo-Pacific geopolitics, leadership and ethics. He has participated in Track 2 discussions with some countries, in various national/international conferences and workshops, and written for national and international journals. He is an adjunct professor at the Naval War College, Goa, and an Honorary Senior Fellow with ANCORS, Wollongong. From July 2024 to January 2025, he was an inaugural Maitri Fellow at ANCORS, researching cooperative maritime physical and digital trade protection.
