Mazagon Dock Shipbuilders Ltd is India’s “Shipbuilders to the Nation” - the country’s only public-sector yard that builds both destroyers and conventional submarines, and the sole supplier of submarines to the Indian Navy. It began in 1774 with a single dry dock in Mumbai that still operates today, was nationalised in 1960, and has since delivered 808 vessels including 33 warships and 8 submarines, all while remaining consistently profitable and debt-free for more than two decades. Everything the company does flows from a single recurring approach: it wins long-term, fixed-price contracts from the Ministry of Defence, then designs and builds complex naval platforms in its own yards using an integrated model that combines in-house design, block-modular construction, and a growing push to replace imported equipment with Indian-made alternatives.
Business segments
Two engines that share the same customer and the same yards - one builds the surface fleet, the other builds and sustains the submarine fleet, and both are fed by the same design and infrastructure backbone.
1. Shipbuilding: the surface fleet that keeps the yard humming
MDL designs and builds destroyers, frigates, and patrol vessels for the Indian Navy and Coast Guard under multi-year contracts, with revenue recognised across the entire project lifecycle from letter of intent to warranty expiry.
- Warships are the core - the division has delivered 7 destroyers between 2014 and 2025, averaging one every 18 months, and is the lead yard for 4 of the Nilgiri-class stealth frigates under Project P17A, three of which were delivered by November 2025.
- Paid across the project, not just at delivery - revenue comes from long-term, fixed-price contracts and is recognised over the normal operating cycle from the effective date of the contract or Letter of Intent right through to the end of the guarantee period, so cash flows are spread rather than lumpy.
- Block construction, not piece-by-piece - the yard shifted from unit assembly to integrated modular construction, using a Module Workshop with two 50-tonne cranes and a retractable roof to fabricate large pre-outfitted hull blocks indoors, which compresses build time.
- Indigenous content is climbing - nearly 75% of the P15B destroyer and P17A frigate is sourced domestically, including hull steel developed with SAIL, and a dedicated ‘Make in India’ department has indigenised 25 items while listing 421 imported items worth roughly ₹2,000 crore for local industry to take up.
- Repair and commercial work fill the gaps - the division also refits naval ships, repairs foreign-flagged commercial vessels from Singapore and South Korea, builds cargo containers for CONCOR, and has taken an MRO contract for MI-17 helicopters for the Nepalese Army.
2. Submarine and heavy engineering: the country’s only public-sector submarine line
MDL is India’s sole public-sector submarine builder, having delivered all 6 Kalvari-class boats under Project-75, and it sustains the fleet through refits while preparing to integrate air-independent propulsion for longer underwater endurance.
- The only submarine factory in the public sector - the division has delivered 8 submarines to the Indian Navy, including two SSK boats built in the 1990s that are still in active service after more than 25 years, and it is currently executing the medium refit and life certification of the first of those boats.
- Two assembly lines, eleven submarines at once - MDL possesses two dedicated submarine assembly lines with capacity to construct 11 submarines simultaneously, an infrastructure asset unique in India, supported by a shore integration facility for rigorous system testing.
- AIP will extend the underwater leg - the company signed a contract worth approximately ₹1,990 crore to design, build, and integrate a DRDO-developed Air Independent Propulsion plug into Scorpene submarines, with plate cutting commencing in March 2025 and delivery due 42 months later.
- Global partnerships for the next generation - MDL has a non-binding MoU with thyssenkrupp Marine Systems of Germany for the P75-I submarine programme and an exclusive MoU with Naval Group of France to offer evolved Scorpene submarines to a friendly country, while a trilateral MoU with the Indian and Brazilian navies covers maintenance know-how.
- Heavy engineering adds heft - the division has revived a heavy engineering and offshore projects vertical that secured orders from ONGC for a pipeline replacement project worth approximately ₹7,000 crore, and it fabricates pressure hull subsections and valves for export.
Shared infrastructure and design backbone
The Mumbai yard is a 250-year-old industrial campus that combines dry docks, slipways, and a 300-tonne Goliath crane with digital tools - and it is being expanded at Nhava to add a greenfield shipyard with a shiplift and repair facility.
- Three dry docks and a wet basin - the Mumbai facility has 3 dry docks, 9 slipways, and a wet basin spanning roughly 27,000 square metres that can accommodate two large frigates and two submarines for outfitting simultaneously.
- Design happens in-house - a large pool of naval architects and engineers has created basic designs for next-generation missile vessels, corvettes, and destroyers, and a Virtual Reality Lab validates 3D models before steel is cut.
- AI and robotics on the shop floor - the yard uses AI-enabled weld inspection machines developed with IIT Madras, an AI-enabled remotely operated vehicle for underwater hull inspections, and a Product Lifecycle Management system that links departments on the stealth frigate programme.
Group structure and partners
MDL is 81% government-owned, has no debt, and recently acquired a controlling stake in Sri Lanka’s largest shipyard while holding a significant minority interest in Goa Shipyard.
- Government-owned with operational freedom - the Government of India holds 81.22% of the share capital, and MDL became the first government-owned shipyard to receive Navratna status in June 2024, giving it greater financial and operational autonomy.
- Colombo Dockyard is now a subsidiary - MDL acquired a 51% controlling stake in Colombo Dockyard PLC, Sri Lanka’s largest shipyard, for approximately ₹236.95 crore, completing the acquisition through a mandatory offer in March 2026.
- Goa Shipyard is an associate - MDL holds a 47.21% stake in Goa Shipyard Limited and consolidates its results, extending its shipbuilding footprint without full ownership.
- A web of international tie-ups - partnerships include an MoU with Asyad Drydock in Oman for commercial and defence repair, selection as preferred production partner for Russia’s SSK Zvezda shipbuilding complex, and a teaming agreement with Swan Defence for landing platform docks.