Approval supports the development of next-generation wind-assisted propulsion systems for large yacht and multihull applications 

Lloyd’s Register (LR) has granted Approval in Principle (AiP) to Rondal for its Aero Wing Sail, following 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. 

The Aero Wing Sail is a rigid wing-sail concept designed for application on large yachts and multihull platforms to provide wind-assisted propulsion capability and ease of integration within vessel layouts. 

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 to identify operational and integration-related risks. LR also provided recommendations for further refinement of the concept. 

Tom Wolodarsky, Senior Surveyor and Lead Specialist WASP, LR, said: “This Approval in Principle reflects Lloyd’s Register’s commitment to enabling innovative technologies that support decarbonisation 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.” 

Hermen de Jong, Innovation Manager, Rondal, commented: “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.”  

The AiP forms part of LR’s wider commitment to supporting the safe and scalable adoption of wind-assisted propulsion technologies. Further insights into technology deployment and retrofit considerations are examined in the report: Applying wind-assisted propulsion to ships, part of LR’s Retrofit Research Programme.