Project 75I is probably the most debated and anticipated submarine projects that India undertook, ever. Project-75I is a follow-on of Project 75 which is based on the Kalvari class (Scorpene-class) submarines that India has been trying to and at last successfully acquired in 2017.  Let us dive into the history of Project – 75I and look at every aspect of the deal in detail.

History of Project – 75

In 1997, the Government of India proposed to buy 25 submarines under the Project – 75 programs. Things took a drastic turn in 1999 when the Kargil war began and after that, the cabinet decided to launch a 30-year submarine acquisition plan which called for two parallel production lines constructing 6 submarines, per line. After this, the older P-75 plan too was brought under this 30-year long program and it was decided that these submarines too will be constructed in India via TOT from foreign manufacturers.

In October 2005, India signed a series of agreements with French DCNS International, the Government of France, and MBDA for a TOT contract to Mazagon Dock Limited. The entire Project – 75 program at that point in time was valued at $ 2.4 billion. This deal too included an offset clause of 30% and the submarines were to be delivered starting from 2012. Steel cutting for the first submarine was started in December 2006 and the hull construction was started in May 2007. As of 2014, the project was running behind schedule by four years. The first submarine of this class, INS Kalvari (based on Scorpene-class) was launched on 28 October 2015 and the sea trials began in May 2016. All of these are to be delivered by 2022.

The Project – 75I was first accepted in November of 2007. In 2008, an RFI was issued to Germany (HDW), Russia (Rosoboronexport) and France (Armaris/DCNS) about constructing six submarines with AIP (Air Independent Propulsion) systems and with land-attack capabilities. This project went back and forth as DAC (Defence Acquisition Council) in July of 2010 had decided to construct four of the submarines in India and buy two of them outright. This was supposedly decided because of the pressure from the then Navy chief who was worried over the alarming state of SSKs. The AIP (Air Independent Propulsion) module was disconnected from P-75 as the development of these systems by DRDO was getting delayed.

In 2014, the DAC which was headed by Late Manohar Parrikar had reverted back to the original plan of building all the six Project – 75I submarines in India, backing the Prime Minister’s “Make in India” slogan with a total budget of around 53,000 crores which involved state-owned Mazagon Docks, Hindustan Shipyard and Cochin shipyard along with privately owned L&T and Pipavav shipyard. In 2017, the government launched the strategic partnership (SP model) model to boost indigenous production.

MDL and L&T were selected as the Indian partners in the end and after that these two companies will have to submit their technical and commercial bids in response to the RFP after forming a joint venture with their preferred OEM (Original Equipment Manufacturer) of foreign origin. Five OEMs were shortlisted by MoD: Rubin design bureau of Russia, Naval group DCNS of France, Thyssenkrupp Marine systems of Germany, Navantia of Spain and Daewoo of South Korea. This project is to be finalized by December of 2021 at latest, according to the reports.

There is also a follow-on project of this Project – 75I, designated as the Project – 76, which will be an indigenous design. The main purpose of Project – 75 and Project – 75I was to provide with time and technology for the Indian navy so that they can make their own designs for future requirements. These submarines will have stealth characteristics and 12 of these submarines will be designed and made in India.

 As we have taken a look at the history of Project 75 and P75I, let us also take a look at the three most favourable submarines and their technical aspects closer and also know how they can cater to the Indian Navy’s needs.

Amur Class Submarines

Amur Class submarines are designed and developed by Rubin Design Bureau of Russia. Amur Class is the export version of the Lada class of submarines which in turn is a modernized version of the Kilo class submarines. These submarines have a surface displacement ranging from 650 to 1850 tonnes and are diesel-electric submarines which were launched in 2004. These submarines are equipped with AIP systems. These submarines incorporate single hull design unlike the traditional double hull design of kilo class submarines. These submarines use hydrogen-oxygen fuel cells for generating electricity and for low noise operation. The surface speed of these boats in 10 knots and the submerged speed is 21 knots. These boats have a cruising range of 7500 nautical miles at a speed of 3 knots. Maximum diving depth is 300 m and the submerged displacement is 2700 tonnes.


These submarines can carry Club-S submarine launched cruise missiles and missiles can be fired from regular torpedo tubes. These boats also have six 533 mm torpedo tubes capable of launching up to 18 torpedoes. These are fitted with modern sonar equipment such as bow, flank array and towed array sonars. The Lira sonar can detect low noise targets at long ranges as well.

The boat also has inertial guidance system for navigation. The counter measures are taken care of by an electronic support measures system, radar warning receiver and direction finder.

SMX 3.0 submarines

SMX 3.0 (SMX Ocean), which is designed as a diesel-electric spin-off of the Barracuda class submarine by DCNS France is one of the contenders for Project-75I. This is a heavier class submarine in terms of surface displacement when compared to other boats in the competition (as well as the Scorpene Class which precedes this). This boat displaces 3000 Tonnes in baseline configuration and up to 4700 Tonnes in ocean configuration. The operational depth will be over 300m. This boat was showcased as a concept in EURONAVAL in 2014 and the first boat will not be inducted before 2021 which makes this a new boat. This boat contains AIP systems as well along with a diesel-electric power plant. The average transit speed will be 14 knots and the maximum range is rumored to be 18000 nautical miles at a speed of 10 knots.


This boat will integrate sensors together with manned and unmanned vehicles that provide the capability of gathering intelligence in all domains. This will also be capable of launching UAVs. This boat will be equipped with a total of 34 weapon systems with five different types of torpedoes, mines, anti-ship missiles, cruise missiles, and anti-air missiles. Vertical launchers in the future can also be included in the future.

S80 Plus submarines

S80 plus class submarines are designed and being developed by Navantia for the Spanish navy. The first ship of this class is planned to enter service in 2021. This will have a displacement of 2200 tonnes surfaced and have a range of 4500 nautical miles (rumored) and this boat will have a speed of 12 knots on the surface and 19 knots when submerged. This submarine’s AIP systems are powered by bioethanol which is quite different from other submarines in this class. The electric propulsions will be 20% lighter than in the Scorpene-class and generate 50% more energy than them.


The sonar suite of these submarines will consist of a cylindrical sonar array, flank array, and a passive ranging sonar along with mine and obstacle detection sonar. This will also have a towed sonar array system, an interception analyzer, and a noise analyzer. This submarine has six 533 mm torpedo tubes and 18 other weapons including mines, DM2 A4 torpedoes, MK48 torpedoes, Harpoon missiles, and Tomahawk cruise missiles. This boat also has a satellite communication system and a guidance automation unit. This boat also has electro optronic imaging systems, hoistable masts, and periscopes.

Why the other designs are rejected

The other two submarines offered by Italy and Germany are the S-1000 class and Type – 214, respectively. The S1000 submarines are a more advanced version of the Amur with a displacement of 1100 tonnes. It was a joint venture between Italy (Fincantieri) and Russia (Rubin) that eventually got canceled due to the Russian annexation of Crimea.

Type 212 Submarine

The Type 214 on the other hand have multiple issues that would not make it competitive amongst other offers for the Indian Navy. First of all, the Type 214 (export version) is a compromised design as compared to the Type 212 variant (German version) which features a non-magnetic steel hull that makes it difficult to be detected by a MAD (magnetic anomaly detector). There have also been issues related to excessive screw noise (propeller cavitation) that gives away the submarine’s position, overheating of the AIP fuel cells, a high degree of rolling when surfaced in bad weather. Smaller technical issues such as inadequate air-independent propulsion system output power, inappropriate periscope vibration, sonar flank array problems, and seawater leakage into the ship’s hydraulics have also been observed by some customer navies.

With regards to the Indian Navy, the Type 214 simply does not fit into the mission characteristics of the P75/75I – 76 programs. The last time the Indian Navy build a German submarine was the two Shishumar Class submarines (Type 209 – 1500) that finished construction in MDL by 1994. Therefore, building another German design would simply not work to bring this program forward. A French design (Kalvari Class) for P75 and a German design for P75I will end up confusing the P76 indigenous program, with too many contractors, shipyards and designs involved.

It is better to look for evolutions of the Scorpene design (principally the SMX3.0 or the S80 Plus) so that P76 will have a clearer design language that can be followed. A long-lasting relationship with a single foreign manufacturer will also bring new technologies (such as bio-mimetic propulsion seen on the SMX 31E concept) and its related transfers to make the P76 a much better performing submarine. The Kilo successor designs such as the S1000 and Amur can also be looked at since India has a large fleet of Kilo Class that it has indigenously refitted as well as Russian help in our nuclear submarine programs as well. Therefore, as far is TOT is concerned, it is a safer bet to go with the French or Russian originated design.

Future Proof Technologies for the P76 Programme and beyond

They are multiple new technologies that each of these three submarines possesses that could be useful for the Indian Navy in their future operations. Since the P75I program needs to be technologically superior from the Kalvari Class, the Indian Navy requires a suite of new technologies that sets it completely apart from the previous submarine classes the Indian Navy possesses.

Carrying special forces divers have been a role that was traditionally designated for nuclear attack submarines (SSN) that have extended endurance. Since India’s traditional threats are within the Indian Ocean Region, using SSNs to perform diver insertion at such near distances appears to be an overkill. The introduction of diver modules to SSKs seems to be an evolutionary design that makes use of the advantage that new SSKs have extended ranges due to their AIP systems. The SMX 3.0 can be outfitted with a swimmer diver delivery dock just as its SSN variant (Barracuda Class). The S80 Plus, on the other hand, does not feature such diver assist systems, although it might be possible to add this in the future as the S80 Plus is essentially a French design. The Amur, on the other hand, does not have any diver centric systems and it features a more traditional design.

AUV (autonomous underwater vehicles) are the next forefront of submarine technologies. It is also crucial to the Indian Navy as numerous private and public players in India have already started to develop it. Therefore, having a submarine design that can allow for AUVs to be launched is extremely crucial for the P75I program and beyond. AUV comes in many varieties and for different job scopes. These include mine-hunting vehicles that can clear a mined area (sea-denial zone) for the mothership, reconnaissance AUV that can conduct surveillance of enemy ports without risk to the submarine as well as saboteur AUVs that can conduct hydrographic surveys of enemy territory as well as sabotage undersea cables. SMX3.0 features a special unmanned underwater vehicle dock (UUV) that can launch and retrieve UUVs using a towed retrievable platform. Neither the S80 Plus nor the Amur Class have a specialized docking mechanism to launch or retrieve AUVs but can use their torpedo tubes to launch some of these UUVs (specially adapted to launch from these tubes).

AIP systems are another area where the Indian Navy wishes to move forward on. Unlike Japan’s modified Soryu Class Submarines which plans to eliminate AIP entirely and rely on only lithium-ion batteries, the Indian Navy cannot afford to ditch the AIP as its patrolling area (for its SSKs) covers the entire Indian Ocean Region (IOR), unlike Japan’s usual territorial patrolling style. All three submarines will have AIP systems.  However, just like the Kalvari Class, the Indian Navy would probably outfit these new submarines with the DRDO-built AIP system (PAFC technology) as well. Since the existing AIP has been designed around the Kalvari Class, the DRDO AIP module might be an easy fit for the french design based S80 Plus and the SMX3.0 but might be a bit of a challenge for the Amur.

VLS capability is the last important technology that the IN wants. The Indian Navy wants a new type of sea denial capability by utilizing SSKs to launch Brahmos missiles which can be used in an anti-ship or surface attack mission profile. This VLS package definitely benefits the Amur Class, which is already stated to have a VLS module specifically for the Brahmos missile. SMX3.0 will also feature a VLS module that could either house the Brahmos (if the Russians agree to integrate onboard a western design) or another Indian indigenous missile (either a conventional warhead scaled-down variant of the Shaurya or another new missile based on the STAR missile). S80Plus does not have an AIP system currently but might be able to be outfitted with a VLS plug in the future.


It seems that the SMX3.0 is the easiest platform for us to transit to as it is an evolutionary design of the existing Kalvari Class. A partnership with a forward-thinking submarine manufacturer like DCNS will also allow us to design more futuristic submarines for the P76 program and ensure that the Indian Navy will become the most dominant SSK power in the region, if not, the world.

Alan Jai Kuriako & Bhagavan Hindustani

By Alpha Defense

Alpha Defense initially a solo venture but now a defense group by people from various demographics of India covering defense news and updates. We believe in unbiased analysis of every subject in hand. Our mission is to provide simplfiied defense information to the public.

8 thoughts on “Project 75I – The Great Indian Submarine saga”
  1. Your information is wrong about smx 3.0 … You describe the specifications of conventional barracuda which offers to Australia in 38.5 dollars for 12 boat….
    Your info is wrong often a times.. So kindly do deep search and then write… God bless india with these type of people…

    1. Data here is based on the EURONAVAL handout from DCNS which one of us collected personally.
      I am sure if you have come up with this conclusion you will have something substantial to back it up.. May I please have that?

      1. Brother that was shortfin barracuda for australian navy… If you just google smx 3.0 then official naval group website describe it properly….

  2. Hey alpha defense your articles are good . Please maintain the standard of your articles . Don’t be like other websites who just publish copied articles from other websites .
    Could you please make a video on indigenious option for electronic attack aircraft ?
    Thank you

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