Kongsberg Maritime has secured a contract to supply its rim-drive thrusters for a new acoustic research vessel being built for India’s Naval Physical and Oceanographic Laboratory (NPOL).
The vessel, under construction at Garden Reach Shipbuilders and Engineers (GRSE), will play a critical role in oceanographic and acoustic research for the Defence Research and Development Organisation (DRDO).
The Kongsberg Maritime rim-drive thrusters were selected for their ability to meet exceptionally strict underwater radiated noise requirements, a key factor for acoustic research operations. By eliminating the traditional gearbox and using an electric rim-drive motor integrated into the propeller hub, these thrusters are designed for ultra-quiet performance, high efficiency, and precise manoeuvrability, as required by sensitive scientific missions.
The thruster package comprises two RD-AZ2600 azimuth thrusters, two RD-TT1600 tunnel thrusters, and the MCON control system.
This contract takes Kongsberg Maritime past 100 units for rim-drive propulsion systems worldwide, a technology that was first launched commercially 10 years ago. Since its introduction, Kongsberg Maritime says its rim-drive solution has become the benchmark for silent, reliable propulsion in research, naval, and specialised commercial vessels.
Nils Reidar Valle, SVP Naval and Workboats, Kongsberg Maritime, said: “We are proud to support NPOL and GRSE with technology that enables world-class acoustic research. Our rim-drive azimuth thruster is the quietest in its class, delivering exceptionally low underwater noise to meet the most demanding research requirements. Crossing the 100-unit milestone is a clear demonstration of our commitment to innovation.”
The azimuth thruster features a six-bladed propeller housed in a nozzle, which improves low-speed thrust and minimises underwater noise. The propeller is integrated with the motor and has no blade tips, reducing cavitation. A permanent magnet motor built into the nozzle eliminates the need for additional cooling, simplifying installation and maintenance. With no gears apart from the steering gear, the design ensures low maintenance requirements.
The advanced acoustic research vessel will feature laboratories and equipment for oceanographic studies, sonar testing, and acoustic signature analysis. With Kongsberg Maritime’s rim-drive thrusters, the vessel will combine operational flexibility with minimal environmental impact, supporting India’s strategic research objectives.
Delivery of the propulsion systems will align with the vessel’s construction schedule at GRSE.
Image: GRSE Indian acoustic research ship (source: Kongsberg)



