Project 75I will significantly enhance India's submarine force posture by introducing advanced, stealthy, and longer-endurance conventional submarines equipped with Air Independent Propulsion (AIP).

These submarines will extend underwater endurance from the current two days (in Kalvari-class Scorpènes) to nearly three weeks, allowing for prolonged covert patrols far from Indian shores. This capability is crucial for sustained sea denial, area control, and enhanced deterrence in the Indian Ocean region under modern surveillance threats.

The project builds on India's existing submarine fleet and industrial base, aiming to move beyond licensed production to co-design and indigenous construction, raising local content up to about 60% by the sixth boat.

This shift will bolster domestic shipbuilding expertise and complement the development of future indigenous and nuclear-powered attack submarines, creating a layered and credible undersea deterrent force.

Strategically, Project 75I addresses critical capability gaps as India faces escalating regional threats from China's expanding navy and Pakistan's acquisition of new AIP-equipped submarines.

The advanced stealth and endurance of these boats will allow the Indian Navy to monitor vital sea lanes, maintain persistent presence in contested waters, and deter adversary incursions, boosting India’s maritime security and power projection.

MDL-TKMS Technology Transfer Levels

The Mazagon Dock Shipbuilders (MDL) and ThyssenKrupp Marine Systems (TKMS) arrangement under Project 75I is designed to deliver a high level of technology transfer that fundamentally strengthens India’s indigenous submarine construction capabilities.

The deal is structured under India’s Strategic Partnership model, which demands comprehensive technology transfer enabling MDL not only to build the six advanced AIP-equipped submarines but also to independently design and produce future submarines, including subsequent projects like Project 76.

TKMS commits to sharing critical technologies, including Air Independent Propulsion systems and advanced combat systems, supported by close collaboration with MDL and Indian defence firms. This includes localising key components such as heavyweight torpedoes and towed sonar systems via partnerships with Indian companies alongside TKMS subsidiaries.

Such measures are aimed at significantly increasing local content in submarine construction to about 60% in later units, beyond the initially proposed 45%, accelerating the Make-in-India initiative.

Moreover, the partnership extends beyond mere manufacturing, involving technology sharing that bolsters India’s defence R&D and sets the foundation for India to evolve into a regional submarine technology hub.

TKMS is also exploring collaborations with Indian research agencies including DRDO to establish production and testing facilities domestically. This arrangement thus ensures a durable and advanced technology base that enhances India’s naval self-reliance and strategic autonomy, representing a substantial leap over prior technology transfer experiences with foreign OEMs.

Timelines And Milestones That Govern Phased Technology Handover

The phased technology handover in the MDL-TKMS Project 75I arrangement is governed by structured timelines and milestones that ensure a gradual and comprehensive transfer of critical know-how. This process typically follows a staged approach with clear phases:

Pre-Handover Phase: This involves preparatory activities such as defining roles and responsibilities, conducting training for MDL personnel, proving prototypes or modules for testing, and preparing detailed handover documentation. This phase ensures readiness and capacity building at MDL before taking over advanced submarine technologies.

Handover Milestone: A formal milestone occurs when TKMS transfers ownership of specific technology components—such as Air Independent Propulsion, combat systems, and critical subsystems—to MDL. This milestone also includes formal sign-offs and acceptance testing to certify operational readiness and adherence to specifications. MDL gradually assumes design and manufacturing control here.

Post-Handover Follow-Up: After the initial handover, continuous monitoring, troubleshooting, and technical support from TKMS continue during early production and commissioning of submarines. This phase ensures that MDL fully assimilates the technologies and processes, with incremental increases in local content and indigenous design responsibility.

Timelines are strategically aligned with the construction schedule of the six submarines, spreading major handover milestones across keel laying, module completion, assembling, and sea trials. Key performance indicators related to knowledge transfer, production capability, and defect management are tracked closely, ensuring steady progress towards India’s goal of around 60% indigenous content by the last submarine build and autonomous future designs.

The MDL-TKMS arrangement is expected to empower India with autonomous submarine design and production capabilities, making it a strategic cornerstone in India’s maritime defence industrial ecosystem and a catalyst for deeper indigenous technological mastery in naval platforms and systems.​

Project 75I is a linchpin in modernising India’s submarine fleet, enhancing operational range, stealth, and indigenous technological capability, thus significantly strengthening India's undersea warfare posture and its ability to shape the Indo-Pacific maritime balance in the coming decades.​

IDN (With Agency Inputs)