Anemoi Marine Technologies and Lloyd’s Register (LR) have released a technical paper advocating closer alignment between the methodologies used to verify the performance of wind-assisted propulsion systems (WAPS).

The research examines how different performance verification frameworks can be used together to improve consistency, transparency and industry confidence in reported fuel savings.

The paper builds on LR’s earlier verification of Anemoi’s methodology for calibrating in-service performance and forecasting models for WAPS. The study evaluates how this approach interacts with two established frameworks: the International Towing Tank Conference (ITTC) guidelines for sea trials and performance prediction, and DNV’s recommended practice for in-service testing.

According to Anemoi, the use of multiple performance analysis methods across the sector currently makes it difficult to compare results and demonstrate a clear business case for installing wind-assisted propulsion technologies.

The analysis suggests the three approaches perform complementary roles. ITTC guidelines focus on short-term verification under controlled testing conditions, while DNV’s recommended practice provides longer-term evaluation based on operational performance. Anemoi’s method links in-service measurements with fuel-saving forecasts.

The study indicates that combining the strengths of these frameworks could provide ship operators with a more standardised tool for assessing the financial benefits of wind propulsion installations.

Anemoi’s verification process, validated by LR in 2025, involves collecting operational data while the wind-assisted propulsion system is alternately activated and deactivated during normal voyages. This data is then used to calibrate performance models that estimate the thrust generated by rotor sails and their impact on vessel fuel consumption.

The company states that the methodology is technology-agnostic and can be applied across different vessel types.

“Accurate measurement and prediction of the real savings made by vessels using WAPS is essential for giving confidence to ship owners and operators who want to harness wind energy in order to reduce environmental impact and fuel costs,” said Luke McEwen, technical director at Anemoi Marine Technologies. “With our verification process and our new efforts pointing to the potential convergence of methodologies, Anemoi is helping to guide the standardisation efforts that are needed to ensure this market flourishes.”

Dr Santiago Suarez de la Fuente, ship performance manager at Lloyd’s Register Advisory, said: “Verification of performance assessment methodologies is a core part of LR’s mission to assure both safety and efficiency standards for maritime stakeholders — and particularly important in emerging sectors where processes have yet to be fully standardised. We are therefore delighted to partner with Anemoi once more to advance understanding of performance verification as the WAPS market matures.”

Founded in 2015, Anemoi Marine Technologies is a UK-based engineering research and development company specialising in Flettner rotor sail systems for commercial vessels. According to the company, typical installations include three to five rotor sails up to 35 metres in height, with each unit capable of saving approximately one tonne of fuel per day and reducing CO₂ emissions by around three tonnes.