Through a Memorandum of Understanding (MoU), Mazagon Dock Shipbuilders Limited (MDL) and Hindustan Shipyard Limited (HSL) have established a strategic partnership to transform India’s submarine construction program, marking a significant advancement for the nation’s maritime defense capabilities. With the goal of greatly boosting the country’s underwater fleet capabilities and achieving the Indian Navy’s ambitious goal of maintaining 20 to 24 submarines for strategic deterrence, this partnership marks a significant departure from India’s historical reliance on a single shipyard model to a dual-coast manufacturing approach.
With a distinct allocation of duties intended to optimize productivity and capitalize on each shipyard’s core capabilities, the Memorandum of Understanding between MDL and HSL creates a thorough framework for collaborative submarine construction projects. Building on its vast experience in submarine manufacturing since the late 1980s, MDL will continue to serve as the lead constructor under this arrangement, with HSL primarily handling outfitting technology. It is anticipated that this strategic division of labor will optimize resource allocation throughout India’s submarine construction programs and greatly speed up production timelines.
With MDL based in Mumbai on the west coast and HSL based in Visakhapatnam on the east, the partnership creates India’s first dual-coast submarine manufacturing capacity. A long-term strategic objective that dates back to 1999, when defense planners recognized the necessity of establishing submarine construction facilities on the east coast to supplement the current west coast capabilities, is fulfilled by this geographic distribution. The dual-coast strategy ensures uninterrupted operations even in the event that one facility experiences operational difficulties by improving operational flexibility, lowering transportation costs, and offering redundancy in manufacturing capabilities.
The Indian Navy currently has a fleet of about 18–19 submarines in various classes as of 2025. Five operational Kalvari-class submarines (designed after the French Scorpene), four Shishumar-class submarines (German Type-199), seven Sindhughosh-class submarines (Russian Kilo), and a number of nuclear-powered submarines under the Arihant-class program make up the current fleet.
But operational availability is a major problem; naval officials admit that the aging Russian Kilo-class submarines have lower availability ratios because they have been in service since the 1980s. While the German-origin Shishumar submarines continue to show good performance and reliability, with an anticipated operational life extension of another ten and a half years, the newer Kalvari-class submarines maintain much higher availability ratios.
For the Indian Navy to effectively combat growing maritime threats and preserve its dominance in the Indo-Pacific area, it has clearly stated that it needs a minimum of 24 submarines. According to government officials, the Navy will be able to keep about 20 submarines available for strategic operations under the dual-shipyard model, which is a major improvement over current capabilities. This goal is in line with larger plans for naval expansion, which call for the Indian Navy to reach 175-200 warships by 2035.
At more than ₹70,000 crore ($8.2 billion), Project 75I is India’s most ambitious conventional submarine acquisition program. Six cutting-edge diesel-electric submarines with Air Independent Propulsion (AIP) technology are to be built as part of the program in order to improve operational endurance and stealth. Since the L&T-Navantia bid was rejected for technical non-compliance, MDL, in collaboration with the German company ThyssenKrupp Marine Systems (TKMS), has become the only contender left.
As part of India’s self-reliance initiative, the P75I submarines will have cutting-edge capabilities that are far beyond those of their predecessors, including sophisticated sensors, weapons systems, and domestic components. It is anticipated that the first submarine under this program will be delivered within seven years of the contract being signed, with deliveries possibly starting as early as 2032. However, concerns regarding execution timelines and cost overruns have been raised by the program’s complexity and strict indigenization requirements.
The Defence Research and Development Organization (DRDO) and the Naval Design Bureau are collaborating to design and develop India’s first conventional diesel-electric submarine, Project 76, which is the country’s most ambitious indigenous submarine development project. The program intends to build 12 submarines with a 3,000-ton submerged displacement that will have cutting-edge features like lithium-ion batteries and in-house weapon control systems.
The project is intended to replace the well-known Sindhughosh (Kilo) class submarines with an air-independent propulsion (AIP)-equipped program. The technological know-how from Project 75’s French technology and Project 76’s German/Spanish collaboration experience are combined. The program is a significant step toward lowering dependency on foreign Original Equipment Manufacturers for submarine design, with the goal of starting prototype construction by 2028.
The Naval Dockyard Visakhapatnam, which builds the Arihant-class nuclear-powered ballistic missile submarines, is the focal point of India’s nuclear submarine capabilities. India joined the select group of countries that operate nuclear-powered ballistic missile submarines when the lead vessel, INS Arihant, was put into service in August 2016 and completed its first deterrent patrol in November 2018.
Approved in February 2015, the Advanced Technology Vessel (ATV) program aims to significantly increase India’s nuclear deterrent capabilities by constructing six nuclear submarines domestically. According to recent strategic analyses, India is making a significant doctrinal shift toward undersea warfare capabilities by giving priority to nuclear-powered attack submarines (SSNs) over more aircraft carriers.
The partnership between MDL and HSL expands on notable advancements in the indigenization of submarine technology, especially through the Kalvari-class program. In order to support the Indian Navy, Naval Group’s collaboration with MDL has produced a vast industrial ecosystem that includes over 50 Indian businesses and an Indian subsidiary that employs over 70 Indian engineers. This ecosystem signifies a significant improvement in India’s capacity to manufacture submarines and technological independence.
Critical submarine technologies have been transferred as part of the indigenization process, and starting with the third submarine in the Kalvari program, Indian companies will be in charge of producing particular submarine equipment. This strategy has improved India’s industrial base in submarine-related technologies and reduced reliance on foreign suppliers while also generating significant job opportunities.
By resolving significant capacity issues and creating a strong basis for long-term naval modernization, the strategic alliance between Mazagon Dock Shipbuilders and Hindustan Shipyard represents a revolutionary advancement in India’s submarine manufacturing capabilities. With MDL’s vast construction experience and HSL’s expanding outfitting and technological capabilities, the partnership capitalizes on the complementary strengths of both shipyards, fostering a synergistic relationship that improves program efficiency overall.
By lowering reliance on foreign suppliers and increasing strategic autonomy in vital defense technologies, the dual-shipyard model puts India in a position to meet its ambitious submarine fleet requirements. The successful implementation of intricate projects like P75I and Project 76, cautious handling of cost escalations, and ongoing investment in workforce development and technology capabilities are all necessary for this partnership to succeed.
The MDL-HSL partnership offers a vital basis for preserving underwater deterrent capabilities and guaranteeing maritime security in the Indo-Pacific area as India negotiates an increasingly complicated maritime security environment. The success of the partnership will not only improve India’s naval capabilities but also make a substantial contribution to the Atmanirbhar Bharat initiative’s larger goals of defense industrialization and technological self-reliance.
