Anemoi Marine Technologies, a private limited company specialising in Rotor Sail wind propulsion systems, has collaborated with the class society Lloyd’s Register Advisory to publish a white paper detailing an in-service performance verification methodology for wind-assisted propulsion systems, according to the company's release.
The paper outlines a process that enables operators to measure vessel performance by toggling the propulsion system on and off under routine voyage conditions, using this data to calibrate predictive models of rotor sail performance and accurately estimate voyage‑by‑voyage fuel and emissions savings.
According to Anemoi, this method reduces both cost and operational complexity compared with existing standards, such as ISO 19030, and avoids the need for dedicated sea trials that disrupt charter schedules.
Dr. Santiago Suarez de la Fuente, Ship Performance Manager at Lloyd’s Register Advisory, noted that current standards for wind‑assisted propulsion verification are limited and commended the robustness and transparency of Anemoi’s methodology, which accommodates a full range of vessel and system operating conditions.
The paper is titled Performance Verification Of Wind‑Assisted Ship Propulsion Systems By On‑Off Testing.
The methodology was recently applied to the bulk carrier TR Lady Kamsarmax, equipped with three Anemoi rotor sails (5 m diameter, 24 m height), over a one-year multi‑voyage trial. Independent analysis showed average net fuel savings of 9.1%—equivalent to 1.9 tonnes of fuel and 7 tonnes of CO₂ per sailing day. In one voyage across the North Pacific, savings reached 21%.
Chris Hughes, Decarbonisation Specialist at Cargill (the vessel’s charterer), highlighted the value of data from more than 167 rotor on/off tests combined with Lloyd’s Register verification in refining weather‑routing models and informing future deployment decisions.
In May 2025, Lloyd’s Register Advisory issued a press release confirming its independent verification of Anemoi’s rotor sail performance data on TR Lady, based on the same methodology detailed in the July white paper.
Anemoi Marine Technologies Ltd is a UK‑incorporated private limited company that designs, manufactures and installs patented Rotor Sail wind propulsion systems. The company’s solutions, developed over 15 years of research and deployed in both retrofit and newbuild projects, are certified by major classification societies. They aim to reduce fuel consumption and greenhouse gas emissions—CO₂, SOₓ and NOₓ—and support compliance with international regulations including EEDI, EEXI, CII, EU ETS.
Lloyd’s Register Advisory is the consultancy division of Lloyd’s Register Group, a global professional services organisation and former marine classification society founded in the 1760s. LR Advisory provides verification, advisory and digital asset‑performance services to maritime and offshore clients, leveraging its expertise in marine engineering, safety and decarbonisation.