The Kalvari-class submarines (), formally classified as the Project-75 submarines (P-75), is a class of diesel-electric attack submarines operated by the Indian Navy (IN). Built by a syndicate of French and Indian shipyards, namely, Naval Group and Mazagon Dock Limited (MDL) respectively, the class is an export derivative of the French-origin , originally designed by Naval Group.
A namesake of the former s that the IN operated between 1967 and 2010, the class was originally planned in the late-1990s as an initial phase of a 30-year long naval rearmament roadmap to replace the IN's conventional submarine fleet, namely the and submarines. India's Ministry of Defence (MoD) placed an order of six submarines in 2005, at a cost of . The final submarine entered service on 15 January 2025.
First introduced to operational service in 2017, the submarines are currently operated by the IN for a variety of missions, namely, littoral surveillance, intelligence gathering, anti-submarine warfare, anti-surface warfare and minelaying operations.
History Origins
In 1997, the Cabinet Committee on Security (CCS), the highest-decision-making body of India's Ministry of Defence (MoD), approved a proposal for the purchase of two Type 209/1500 attack submarines (SSK) for the Indian Navy (IN), at a then-estimated cost of . The two examples of the design, originally conceived by the German-based Howaldtswerke-Deutsche Werft, were proposed to be built at Mazagon Dock Shipbuilders (MDL), located in Mumbai, with the assistance of a foreign naval firm in a corroborative role.
In accordance with the scheme, the IN and MDL approached several naval enterprises for assistance; however, the French-based Thomson-CSF (TCSF) was the only firm willing to participate. Two years later, in 1999, the MoD approved a two-phase plan to build 24 submarines over a 30-year period. For the first phase, which called for the construction of SSKs at MDL, two options were proposed: the former option recommending the construction of the Type 209/1500 at MDL with the assistance of TCSF; the latter option recommending the construction of SSKs based on the newer submarine design, conceived by the French-based Armaris (later DCNS, now Naval Group).
Ultimately, the IN chose the latter, reasoning that the Scorpène, which had been offered with a provision of technology transfer (TOT), was more advanced than the Type 209/1500. Another reason for choosing the Scorpène design was because of the IN's interest in acquiring submarine-launched missiles. At the time, the French-designed Exocet, the US-designed Harpoon and the Russian-designed Kalibr were the only such missiles that were commercially obtainable; however, the Harpoon was unavailable to the IN and the Kalibr was incompatible with the Type 209/1500's torpedo tubes. This led to the Exocet being preferred and subsequently, the Scorpène design. It was also thought that the Scorpène design won the deal because of its capability to fire Exocet anti-ship missiles and an agreement on the air-independent propulsion (AIP).
Order On 6 October 2005, India signed a series of contracts for transfer of technology to construct six submarines at MDL with Armaris, along with the supply of SM39 Exocet missiles manufactured by MBDA. DCN International was designated as the prime contractor in partnership with Navantia. Armaris was responsible for supply of combat systems and technical advisors for construction of submarines at MDL. Valued at a then-total cost of €2.4 billion, the deal included a 30% offset clause and a delivery timeline wherein the six ordered units were to be delivered between 2012 and 2017.
Add-on programme On 10 July 2023, the Indian Navy formally proposed the plans to acquisition of three additional submarines to the Ministry of Defence along with the same for 26 Rafale M aircraft. On 13 July, the Defence Acquisition Council (DAC), headed by the Defence Minisiter Rajnath Singh, of India granted the Acceptance of Necessity (AoN) for the add-on submarine and fighter aircraft projects for the Navy. On 11 August, Mazagon Dockyard was officially approached for the project.
In December 2023, MDL submitted a bid to construct the three submarines, equipped with higher measures of indigenously developed technology along with an AIP module for enhanced underwater endurance. By June 2024, the price negotiations for the project were at advanced stages. Initially, the bid was sent back by the Navy since the cost estimate had exceeded . The entire upgraded combat management system for the proposed submarines would be indigenously developed by Bharat Electronics Limited. The first submarine shall be delivered after six years of contract signing.
As of 13 January 2025, the deal worth would be cleared by the Cabinet Committee on Security by early February while the contract could be signed during the visit of the Indian Prime Minister Narendra Modi to France on 11 and 12 February. As per a report on 9 February, the final cost of the project was around post cost negotiations, excluding the cost of the air-independent propulsion systems. The project was being pursued under the Buy (Indian) category of Defence Acquisition Procedure (DAP) 2020.
The high costs for the three P-75 (add-on) submarines were attributed to their relatively larger size, similar to of the Brazilian Navy, and a higher indigenous content of 60% which is twice of the initial batch of submarines. Moreover, the submarines will have double the mission endurance with higher accommodations, increased food and water storage, and expanded sanitary and oil storage facilities as well as double armament storage and is also expected to configure additional weapons. Additionally, the diesel generators, with 20% improved efficiency and reduced lower vacuum build-up while snorting, will be sourced from a different firm and the electric motors will be upgraded to operate at lower power consumption and ease maintenance. The design also incorporates improved stealth capabilities with reduced infrared signatures.
Though the cost negotiations were completed with the documents submitted by 7 July 2025, a report on 27 July suggested that the Indian Navy has proposed a follow-on deal for three Project-75 (India) submarines instead of pursuing the P-75 (add-on) programme for three upgraded Scorpène-class submarines. If approved by the CCS, the P-75(I) follow-on deal could be finalised within a year of the original P-75(I) contract, which would be finalised by fiscal year 2025–26. As a result, no further orders for Scorpène submarines are anticipated. The Navy favours the P-75(I) class due to its superior stealth, advanced capabilities, and the lack of an operational AIP system in the Scorpène, which is based on an older-generation design.
A report published on 14 October states that the Indian Navy considered the P-75I design a generation ahead of the Scorpène. While the government had not officially "scrapped" the deal yet, the project is not being pursued as per a top government official. The Navy is "not keen" in the deal as of March 2026, though Naval Group has re-affirmed its support to the project.
Construction 2006–07 The steel cutting for the first submarine, the Kalvari, commenced on 14 December 2006, with its hull construction beginning on 23 May 2007. However, work stalled when public disclosures revealed that the 2005 agreement had omitted the procurement of specific components, including engines, generator and raw materials. The issue prompted the MoD to establish a public entity, the Mazagaon Procured Materials (MPM), to directly procure the aforementioned materials. Protracted negotiations between the MoD and DCNS for the components lead to the additional sanctioning of by the CCS, which further delayed the project by two years.
2010–19 In 2011, The project suffered another setback following a breach and flooding at MDL's dockyard in which components, including sections of the already fabricated hull of at least one of the six units, were submerged under seawater; however, the incident was dismissed by the IN as a "minor obstacle".
In 2015, the project suffered further delays after Navantia exited the project. After eight years in construction, Kalvari was finally launched in October 2015 and commenced sea trials a year later, on 1 May 2016.
In June 2016, initial plans to purchase ninety-eight Black Shark torpedoes from the Italian-based munitions manufacturer Whitehead Alenia Sistemi Subacquei (WASS) were cancelled in response to corruption allegations against WASS's sister company, AgustaWestland. Although alternatives, such as the SeaHake torpedoes from Germany's Atlas Elektronik and the F21 torpedoes France's Naval Group were considered, the MoD resorted to installing its existing inventory of older AEG SUT 264 torpedoes on the submarines as a stopgap measure.
The second unit, the Khanderi, was launched in January 2017, which was soon followed by the commissioning of Kalvari in December 2017. The third and fourth units, the Karanj and the Vela respectively, were launched between January 2018 and May 2019, while Khanderi was commissioned in September 2019.
The AIP programme began in June 2017, at a cost of .
2020–23 The fifth unit, the Vagir, was launched in November 2020, while Karanj and Vela were commissioned between March and November 2021, respectively.
The sixth and final unit of the class, the Vagsheer, was launched in April 2022, which was soon followed by the commissioning of Vagir in January 2023. The same month, India's Naval Materials Research Laboratory (NMRL) and Naval Group reached an agreement to integrate NMRL's locally developed AIP technology into the six submarines. Vagsheer commenced its first sea sortie in May 2023, with delivery scheduled for early 2024. On 22 June, Larsen & Toubro signed a contract with DRDO for the construction of two units of AIP system modules for the Kalvari class.
2024–25 February 2024: The Defence Acquisition Council (DAC) granted an Acceptance of Necessity (AoN) in February 2024 for the purchase of forty-eight heavyweight torpedoes for the submarines under a global tender as a stopgap measure until an indigenous option, supposedly a submarine-launched version of Varunastra torpedo, becomes available.
September 2024: On 14 September, the Indian Navy commissioned the Kalvari Submarine Escape Training Facility, Vinetra, at , Visakhapatnam to train personnel in escape procedures during a distress situation. The facility was constructed by Larsen & Toubro and is equipped with a escape tower integrated with an adjacent diving basin.
December 2024: On 30 December, the Indian Ministry of Defence signed two contracts with Mazagon Dock Limited (MDL) and Naval Group, France for upgrades related to the Kalvari-class submarines. The first contract, the one signed with MDL [worth ], is for the construction and integration of AIP Plug into the submarines, while the second contract signed with Naval Group [worth ] is for the integration of indigenous Electronic Heavy Weight Torpedo (EHWT) systems.
January–March 2025: The final submarine, INS Vagsheer, commissioned on 15 January. On 18 March, MDL announced the commencement of production plate cutting for AIP plugs under the contract signed earlier to retrofit air-independent propulsion modules into the submarines.
April 2025: Italy's Black Shark torpedo was reportedly the frontrunner for the 48 heavyweight torpedo tender. Meanwhile, Germany's ThyssenKrupp Marine Systems exited the tender and France's Naval Group offer was higher priced. The project is a revival of the Navy's 98 torpedo procurement in 2008–09, which was dropped in 2013 due to a corruption scandal.