Winds of Change Project Report: comparison of predicted power savings with sea trial measurements for a prototype FastRig wingsail instillation

Abstract

The Winds of Change project, led by Smart Green Shipping in partnership with the University of Southampton and supported by UK Government funding, conducted the first full scale demonstration and validation of the FastRig wingsail technology on a commercial vessel. The study compared high fidelity performance predictions against sea trial measurements to assess the propulsion benefit of a 20 m prototype wingsail installed on a 104 m cargo ship.
Powering predictions were generated using a four degree of freedom performance prediction model that couples aerodynamic forces from high resolution CFD simulations with hydrodynamic forces derived from towing tank experiments. Aerodynamic loads were computed using full scale RANS simulations of the FastRig mounted on the vessel, capturing wing–hull interaction effects and optimal trim conditions. Hydrodynamic forces including resistance, side force, heel, leeway, yaw moments, propeller loading and rudder effects were characterised through systematic model tests. These datasets were integrated in a steady state solver that balances aerodynamic, hydrodynamic and propulsion forces to predict ship speed, rpm, power requirements and thrust contributions under realistic wind conditions.
Model predictions were evaluated against real world data from 41 sea trial paired runs, conducted under the ITTC (2024c) methodology for wind assisted propulsion trials. After data screening, 21 runs met the quality criteria required for paired run analysis.
Across the dataset, measured performance demonstrated that the prototype FastRig delivered both increased vessel speed and reduced shaft power under wind assist conditions, even at relatively small true wind angles. The prediction model showed good agreement with the measured performance. Differences in speed increase were within ±0.1 knots, matching typical sea trial accuracy, and power reduction discrepancies remained below 0.25% of maximum shaft power. Total brake power savings, combining both speed increase and propeller unloading, followed the same trend with average differences of just 8.3 kW. This confirms the model’s ability to capture aerodynamic and hydrodynamic interactions reliably.
The close agreement between prediction and measurement demonstrates that the modelling framework provides a robust and credible basis for estimating wind assisted ship performance. The findings reinforce the value of integrating high fidelity prediction tools with carefully executed sea trials to support the adoption of wind propulsion technologies across the maritime sector. The work also provides guidance for future optimisation of FastRig designs, control systems, and validation methods as the technology progresses toward full scale commercial deployment.

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Identifiers

ORCID for Joseph Banks: orcid.org/0000-0002-3777-8962

ORCID for Dominic Hudson: orcid.org/0000-0002-2012-6255

ORCID for Stephen Turnock: orcid.org/0000-0001-6288-0400

ORCID for Saeed Hosseinzadeh: orcid.org/0000-0002-5830-888X

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