Lloyd’s Register (LR) has granted approval in principle (AiP) to Rondal for its Aero Wing Sail. This rigid wing-sail concept is designed for application on large yachts, sailing catamarans and wind-assisted monohulls to provide wind-assisted propulsion capability and ease of integration within vessel layouts.
The AiP follows completion of concept-level assessment activities in line with LR’s Guidance Notes on Wind Assisted Propulsion Systems (2025). The AiP was awarded in a ceremony at Metstrade 2025 in Amsterdam.
Over the past years, Rondal has worked on developing a reliable and efficient wing sail. The system is designed with a focus on aerodynamic performance, safety, automated control and practical onboard integration. It is developed in collaboration with Artemis Technologies and it is derived from technology used for wing sails in the America’s Cup and SailGP.
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No conceptual issues towards compliance
The AiP confirms that the Aero Wing Sail concept has been reviewed against relevant safety, structural, mechanical, and aerodynamic considerations. The evaluation included computational fluid dynamics (CFD) analysis, structural design review and mechanical system evaluation and a preliminary hazard identification study to identify potential remaining risks and how they are controlled.
The AiP confirms that the wing sail’s design show no major conceptual issues that would prevent the gaining of classification and regulatory compliance. Lloyd’s Register has also provided guidance for further refinement.
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Ready for application
Rondal has been developing composite solutions and integrated sailing systems for nearly fifty years. The Aero Wing Sail builds on this experience with a design that supports both performance and ease of use. With this AiP, the company is ready to move forward with the next development steps and to collaborate with owners, architects and shipyards.
Hermen de Jong, Innovation Manager, Rondal: ‘This approval in principle is an important achievement for Rondal. It demonstrates the maturity of the Aero Wing Sail and that we are ready for application in new yacht projects.’
‘Rondal’s approach to the Aero Wing Sail development shows a clear focus on safety, performance and practical integration,’ adds Tom Wolodarsky, Lead Specialist WAPS, at Lloyd’s Register. ‘This AiP recognises the potential of the design and marks a positive step for wind-assisted propulsion in the yachting sector.’
Picture (top): Rondal’s Aero Wing Sail concept (image by Rondal).
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