Anemoi rotor sails on NSU Tubarao at Zhoushan Xinya Shipyard. Source | Anemoi

Composite rotor sails developer Anemoi Marine Technologies Ltd. (Anemoi, London, U.K.) has completed the retrofit of another large vessel after installing five 35-meter-tall units on the 400,000 DWT ore carrier NSU Tubarao.

NSU Tubarao is a 361-meter-long, 65-meter-beam VLOC delivered in September 2020. With a deadweight tonnage of 399,717, it is amongst the largest bulk carriers in the world. The vessel, owned by bulk owner/operator NS United Kaiun Kaisha Ltd. (NSU, Tokyo, Japan) and chartered by mining giant Vale International (Rio de Janeiro, Brazil), is expected to reduce fuel consumption by 6-12% annually using the wind-assisted propulsion system.

This marks the fourth very large ore carrier (VLOC) vessel installation of Anemoi rotor sails on vessels chartered by Vale (read “Anemoi rotor sails successfully installed on Taiwanese bulk carrier”). The completion of this installation means Anemoi has also surpassed 1.6 million DWT of vessel tonnage installed with its rotor sails.

The rotor sail installation on the 5-year-old vessel, currently operating under a long-term charter to transport iron ore for Vale, was completed during scheduled drydocking in October 2025 in Zhoushan Xinya Shipyard Co. Ltd. in China. The rotor sails are deployed using a folding (tilting) mechanism for flexibility during cargo handling.

NSU has taken a novel approach by combining Anemoi’s rotor sails with advanced digital solutions that optimize power usage and vessel routing, enhancing fuel efficiency on NSU Tubarao while maximizing the use of wind energy. Manta’s FuelOpt offers flexible power management of the main engine, including optimization of fuel saved by the rotor sails. Coupled with Napa’s Voyage Optimization toolbox for voyage planning, these systems maximize the benefit of favorable winds without compromising departure or arrival times.

During the scheduled survey, NSU Tubarao was also equipped with a new shaft generator designed to enhance the efficiency of the vessel. This upgrade not only improves the vessel’s own energy performance but also optimizes fuel consumption when operating Anemoi’s rotor sails. Anemoi successfully integrated its rotor sail technology with the vessel’s shaft generator through advanced control system integration, ensuring seamless coordination between wind propulsion and onboard power supply. 

“The scale of this project shows the market’s growing confidence in wind power as a crucial enabler of lower-emission shipping,” says Clare Urmston, CEO of Anemoi. “Working with progressive partners like NSU, Vale and Class NK, we are able to advance rotor sail technology and show how optimizing propulsion integration and navigation for wind assistance can deliver even greater benefits.”