India is studying the feasibility of developing one of the largest XLUUVs in the world

India’s Ministry of Defence (MoD) has initiated a project to design and develop Extra Large Unmanned Underwater Vehicles (XLUUV). A document released last month by the MoD indicates that the Indian Navy is interested in procuring up to 12 XLUUVs once a prototype is built and clears all trials reported Naval News.

According to the document, the XLUUV may have a maximum ‘length with payload’ of up to 50 meters, width of up to 5 meters, height no more than 10 meters and gross weight without ballast under 300 tons.

This would make it one of the largest submarine drones envisioned to date comparable to Germany’s Modifiable Underwater Mothership, US Navy’s Orca XLUUV and Russia’s Sarma-D, all of which are in the prototyping phase. China is also working on multiple XLUUV projects. It should be noted that the Indian project is in the initial stages and specifications may change considerably as the project progresses.

The XLUUV is intended for the following roles: ISR, anti-submarine warfare, anti-surface warfare and mine warfare. Autonomous features are a key requirement under which the vessel should be capable of deploying from a pier, conducting operations in shallow and restricted waters and returning to harbor on its own. It must be capable of being transported by motherships and trailers on land.

An external payload of up to 10 tons of armament is also under consideration, with the MoD probing the feasibility of mounting two 533 mm torpedo tubes and mine laying capability for the XLUUV.

Submerged maximum speed is specified as at least 8 knots with cruising speed of over 4 knots. Propulsion options may include integrated thrusters or propellers using electric motors. The XLUUV is mandated to have a maximum endurance of over 45 days using either Li-Po/Li-ion batteries or a fuel cell based Air Independent Propulsion (AIP) system as the power source. A diesel generator may be used to recharge any batteries.

Sensors fitted on the XLUUV would include a flank array sonar, towed array sonar, bow sonar, multi-beam echo sounder sub-bottom profiler, collision avoidance sonar, I band radar, ESM system and a periscope mast with EO/IR cameras. It would be capable of communicating with other platforms and control stations using SATCOM and underwater communication systems.

The project was Approved-in-Principle (AiP) on January 16, 2023, with prototype development expected by 2025. Other Make-I projects that were accorded AiP on January 16 are: 15 ship-borne 30kW laser weapon systems, eight 12 MW electric propulsion systems and 55 gas turbine generators of 4 MW class.

Major shipbuilders like Mazagon Dock Shipbuilders Limited (MDL) and Larsen & Toubro (L&T) can be expected to take part in the project. MDL had issued an expression of interest in March 2022 for collaboration with global firms in design, development and construction of XLUUVs. L&T has a portfolio of AUVs and offers midget submarine designs to the Navy.

The procurement of a dozen XLUUVs would aid the Indian Navy in bridging the glaring projected gap in its underwater capabilities due to significant delays to Project-75I, under which six diesel-electric submarines with sea proven AIP are to be built in India by MDL or L&T, with transfer of technology. Eight smaller High Endurance Autonomous Underwater Vehicles (HEAUV) are also planned to be inducted. These containerized eight ton vessels would be capable of anti-submarine warfare and mine countermeasure operations, with an endurance of over two weeks.