Lloyd’s approval for the Rondal Aero wing sail
Rondal has received an Approval-in-Principle (AiP) from Lloyd’s Register during Metstrade 2025 for the Aero Wing Sail.
This recognition confirms that the system’s design and safety principles have been thoroughly reviewed and are ready for the next steps toward implementation.
Questions
Though lots of information about this Wing Sail is available, there remain several questions. Although stemming from the yacht racing and superyacht worlds, would this system work on commercial shipping or even inshore cargo vessels? How much windage remains after lowering the system? Over the past years, Rondal has worked on developing a reliable and efficient wing sail suitable for both sailing catamarans and wind-assisted monohulls. 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.
Comprehensive assessment of safety and design
The Approval-in-Principle follows an extensive evaluation against the requirements of the LR Guidance Notes on Wind Assisted Propulsion Systems (2025). The evaluation included computational fluid dynamics analysis, Structural Design and Analysis, Mechanical system design 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.
A step forward for wind-assisted propulsion
“This Approval-in-Principle is an important achievement for Rondal,” says Hermen de Jong, Innovation Manager at Rondal. “It demonstrates the maturity of the Aero Wing Sail and that we are ready for application in new yacht projects.”
Tom Wolodarsky, Lead Specialist WAPS, at Lloyd’s Register, adds: “Rondal’s approach to the Aero Wing Sail development shows a clear focus on safety, performance and practical integration. This Approval-in-Principle recognises the potential of the design and marks a positive step for wind-assisted propulsion in the yachting sector.”
“This Approval-in-Principle reflects Lloyd’s Register’s commitment to enabling innovative technologies that support decarbonization and operational efficiency. Wind-assisted propulsion is a vital step toward reducing emissions, and we are proud to collaborate with Rondal in bringing this solution closer to market readiness.”
Built on decades of expertise
Rondal has been developing composite solutions and integrated sailing systems for nearly 50 years. The Aero Wing Sail builds on this experience with a design that supports both performance and ease of use. With this Approval-in-Principle, Rondal is ready to move forward with the next development steps and to collaborate with owners, architects and shipyards.
Less crew
Fossil fuel consumption and high greenhouse gas emissions are an unavoidable aspect of large motor yachts. Large sailing yachts have a much lower environmental impact when they are under sail. Conventional sailing rigs can take time and crew effort to set up, manage and take down. Consequently, shorter passages are (too) often made under power. Although a sailing yacht’s slender hull shape has far less resistance under power, this reduces, but does not fully address the environmental impact.
Prototype tested
The wing sail holds a rigid shape which leads to efficient wing profiles, and for example a lower heeling moment for the same forward thrust. Flaps are used to alter the camber, which can control the power of the wind via an automated system. An in-house-built prototype was extensively tested, and dynamic simulations were performed in parallel.
Source: Rondal (PDF, 16 MB)
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