In a landmark development for India's maritime defence capabilities, Mazagon Dock Shipbuilders Limited (MDL) and Hindustan Shipyard Limited (HSL) have forged a strategic partnership through a Memorandum of Understanding (MoU) to revolutionise the country's submarine construction program. This collaboration represents a pivotal shift from India's historical reliance on a single shipyard model to a dual-coast manufacturing approach, aimed at significantly enhancing the nation's underwater fleet capabilities and meeting the Indian Navy's ambitious target of maintaining 20 to 24 submarines for strategic deterrence.

The MoU between MDL and HSL establishes a comprehensive framework for joint submarine construction projects, with a clear division of responsibilities designed to maximize efficiency and leverage each shipyard's core competencies. Under this arrangement, HSL will be primarily responsible for providing outfitting technology, while MDL will continue its role as the lead constructor, building upon its extensive experience in submarine manufacturing since the late 1980s. This strategic division of labour is expected to significantly accelerate production timelines and optimise resource allocation across India's submarine construction programs.

Geographic And Operational Advantages

The collaboration establishes India's first dual-coast submarine manufacturing capability, with MDL operating from Mumbai on the west coast and HSL from Visakhapatnam on the east coast. This geographic distribution fulfils a long-term strategic goal dating back to 1999, when defence planners identified the need to create submarine construction facilities on the east coast to complement the existing west coast capabilities. The dual-coast approach enhances operational flexibility, reduces transportation costs, and provides redundancy in manufacturing capabilities, ensuring continuous operations even if one facility faces operational challenges.

Fleet Composition And Operational Availability

As of 2025, the Indian Navy operates a submarine fleet of approximately 18-19 submarines across multiple classes. The current fleet composition includes five operational Kalvari-class submarines (French Scorpene design), four Shishumar-class submarines (German Type-209), seven Sindhughosh-class submarines (Russian Kilo), and several nuclear-powered submarines under the Arihant-class program.

However, operational availability presents significant challenges, with naval officials acknowledging that the aging Russian Kilo-class submarines have reduced availability ratios due to their operational history spanning since the 1980s. The newer Kalvari-class submarines maintain much higher availability ratios, while the German-origin Shishumar submarines continue to demonstrate good reliability and performance, with an expected operational life extending another decade and a half.

The Indian Navy has articulated clear requirements for a minimum of 24 submarines to effectively counter increasing maritime threats and maintain dominance in the Indo-Pacific region. Government officials have indicated that the dual-shipyard model will enable the Navy to maintain approximately 20 submarines available for strategic operations, representing a significant improvement over current capabilities. This target aligns with broader naval expansion plans that envision the Indian Navy growing to 175-200 warships by 2035.

Major Submarine Programs And Future Projects: Project 75I (P75I) - Advanced Conventional Submarines

Project 75I represents India's most ambitious conventional submarine acquisition program, valued at over ₹70,000 crore ($8.2 billion). The program calls for the construction of six advanced diesel-electric submarines equipped with Air Independent Propulsion (AIP) technology to enhance stealth and operational endurance. MDL, in partnership with German firm ThyssenKrupp Marine Systems (TKMS), has emerged as the sole remaining contender after the disqualification of the L&T-Navantia bid due to technical non-compliance.

The P75I submarines will feature cutting-edge capabilities significantly beyond their predecessors, incorporating advanced sensors, weapons systems, and indigenous components as part of India's self-reliance initiative. The first submarine under this program is expected to be delivered within seven years of contract signing, potentially beginning deliveries as early as 2032. However, the program's complexity and stringent indigenisation requirements have raised concerns about execution timelines and cost overruns.

Project 76 - Indigenous Submarine Development

Project 76 represents India's most ambitious indigenous submarine development initiative, with the Defence Research and Development Organisation (DRDO) working in collaboration with the Naval Design Bureau to design and develop India's first fully indigenous conventional diesel-electric submarine. The program aims to construct 12 submarines with a submerged displacement of 3,000 tons, featuring advanced capabilities including indigenous weapon control systems and lithium-ion batteries.

The project is envisioned as an air-independent propulsion (AIP)-equipped program that will succeed the renowned Sindhughosh (Kilo) class submarines. Project 76 amalgamates technological expertise gained from the French technology of Project 75 and the German/Spanish collaboration experience from previous programs. The objective is to initiate construction of the prototype by 2028, with the program representing a pivotal milestone in reducing reliance on foreign Original Equipment Manufacturers for submarine design.

Nuclear Submarine Programs

India's nuclear submarine capabilities are centred at Naval Dockyard Visakhapatnam, which constructs the Arihant-class nuclear-powered ballistic missile submarines. The lead vessel, INS Arihant, was commissioned in August 2016 and achieved its first deterrent patrol in November 2018, marking India's entry into the exclusive club of nations operating nuclear-powered ballistic missile submarines.

The Advanced Technology Vessel (ATV) program, approved in February 2015, calls for the indigenous construction of six nuclear submarines, representing a significant expansion of India's nuclear deterrent capabilities. Recent strategic analyses suggest that India is prioritizing nuclear-powered attack submarines (SSNs) over additional aircraft carriers, indicating a major doctrinal shift toward undersea warfare capabilities.

Indigenisation Achievements

The collaboration between MDL and HSL builds upon significant achievements in submarine technology indigenisation, particularly through the Kalvari-class program. Naval Group's partnership with MDL has created an extensive industrial ecosystem involving more than 50 Indian companies, along with an Indian subsidiary employing over 70 Indian engineers to support the Indian Navy. This ecosystem represents a substantial advancement in India's submarine manufacturing capabilities and technological self-reliance.

The indigenisation process has involved the transfer of critical submarine technologies, with Indian companies taking responsibility for manufacturing specific submarine equipment from the third submarine onward in the Kalvari program. This approach has not only reduced dependence on foreign suppliers but has also created substantial employment opportunities and enhanced India's industrial base in submarine-related technologies.

Conclusion

The strategic partnership between Mazagon Dock Shipbuilders and Hindustan Shipyard represents a transformative development in India's submarine manufacturing capabilities, addressing critical capacity constraints while establishing a robust foundation for long-term naval modernisation. The collaboration leverages the complementary strengths of both shipyards, with MDL's extensive construction experience and HSL's growing outfitting and technological capabilities creating a synergistic relationship that enhances overall program efficiency.

The dual-shipyard model positions India to meet its ambitious submarine fleet requirements while reducing dependence on foreign suppliers and enhancing strategic autonomy in critical defence technologies. However, the success of this partnership will depend on effective execution of complex programs like P75I and Project 76, careful management of cost escalations, and continued investment in technological capabilities and workforce development.

As India navigates an increasingly complex maritime security environment, the MDL-HSL collaboration provides a crucial foundation for maintaining underwater deterrent capabilities and ensuring maritime security in the Indo-Pacific region. The partnership's success will not only enhance India's naval capabilities but also contribute significantly to the broader objectives of defence industrialisation and technological self-reliance under the Atmanirbhar Bharat initiative.

IDN (With Agency Inputs)