Anemoi crafts verification method for wind propulsion system performance

July 21, 2025, by Sara Kosmajac

UK-based wind-assisted propulsion provider Anemoi Marine Technologies has crafted an in-service performance verification process said to cut costs and ‘improve’ accuracy.

According to Anemoi, the new methodology’s goal is to pave the way for the larger uptake of the climate-neutral, energy-saving benefits of wind-assisted propulsion solutions (WAPS). The process has been verified by the UK’s classification society Lloyd’s Register (LR).

As informed, the methodology, published in a new whitepaper titled “Performance Verification Of Wind-Assisted Ship Propulsion Systems By On-Off Testing”, is compatible with all WAPS. It involves calculating vessel data when the wind propulsion system is turned on and off while encountering various conditions during regular operation.

This data is reportedly used to then calibrate predictions on forces generated by the rotor sail system and their effect on the ship. In turn, officials from Anemoi have shared that this can be used to predict fuel savings. It is understood that the process can be applied throughout the ship’s lifecycle, either in real-time or on a journey-by-journey basis.

As a result, the British WAPS provider explained that the process is expected to practically eliminate the challenges of applying traditional methodologies to WAPS assessment and the operational changes like taking vessels off hire to perform dedicated wind propulsion system sea trials.

As disclosed in the whitepaper, Anemoi and Lloyd’s Register recently revealed the results of the 82,000 dwt bulk carrier TR Lady, which is owned in funds, managed by Tufton and chartered by Cargill. The ship was equipped with three 24-meter-high rotor sails developed by Anemoi.

After a year of testing, it was divulged that the average net propulsion fuel savings were 9.1% and 7 tonnes of CO2e (well-to-wake) per sailing day.

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With growing pressure to meet international emission reduction mandates, including EEDI, EEXI, and the Carbon Intensity Indicator (CII), many shipowners have been turning to rotor sails as an effective net-zero solution to ‘enhance’ vessel energy efficiency.

In October 2024, Anemoi was tapped by Japanese maritime transport company NS United Kaiun Kaisha (NS United) and Brazilian mining giant Vale to fit its rotor sails on a 400,000 dwt very large ore carrier (VLOC).

The following month, Taiwanese shipping player U-Ming Marine Transport commissioned Anemoi to equip rotor sails on a 325,000 dwt VLOC, with the anticipation of achieving 10-12% fuel and emission savings.

In mid-May 2025, Anemoi Marine Technologies, Norway’s classification society DNV, Singapore-based tanker owner Hafnia and China-based shipbuilder Guangzhou Shipyard International (GSI) joined forces to engineer the integration design of rotor sails suitable for installation on 50,000 dwt medium-range (MR) tankers.

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