Design and Production of a Wooden Thames A Rater Class Sailing Yacht

The niche market for modern classics, combining traditional wooden boats with the latest design and manufacturing technology, has been expanding in the past decade, particularly in the United Kingdom. Yachts such as the Thames A Raters remain among the most competitive racing classes, featuring extreme high aspect ratio carbon rigs and wooden hulls over a century old. This example of a modern classic motivated the conception of the next generation of A Raters. The design was developed under the strict class rule and in close relation with the class association and sailors to ensure that the original spirit of the yachts would be conserved. Furthermore, the design brief incorporated the client’s requirements, as well as the shipyard’s restrictions and environmental constraints. Finally, the RCD/ISO standard regulation has been adopted. Hydrodynamic optimisation has been a major interest to improve the performance, despite the imposed hull shape. Indeed, only an exact replica of an existing A Rater is allowed. However, a loophole in the class regulation allowed for some modifications to the hull shape. Based on the Delft systematic yacht hull series, parametric optimisation has been utilised to reduce the hull resistance. Furthermore, multiple centreplate and rudder planforms have been compared using computational fluid dynamics to adopt the most efficient ones. Coupled with the decrease in hydrodynamic resistance, the more powerful sails led to a higher level of performance, quantified thanks to a six degrees of freedom velocity prediction program. In order to reflect the planning capabilities of the boat, the fundamental principles of Savitzky’s planning theory have been adapted and incorporated to maximise the accuracy. In terms of design, the main priorities were to create an aesthetically pleasing yacht, taking advantage of the natural beauty of vanished woods, as well as a more practical layout, better suited to modern racing. As a result, the cockpit was a particular area of interest: a simpler and more ergonomic layout has been developed, with a higher level of comfort for the crew. To achieve a light boat that can be built faster and at a lesser cost than the traditional carvel technique, cold moulding has been preferred. The structural design was developed in accordance with the relevant regulatory bodies and considering the manufacturing constraints. Eventually, a realistic cost estimate and detailed planning were elaborated. A complete set of drawings have been provided to detail the multiple aspects of the design, as well as specify the materials and production methods involved. The final design fully answers the pre-established specifications, with significant improvement in performance while retaining the traditional spirit of the class. The complete design and production allows for the building to be started, and the careful consideration of the various regulations ensures that the boat will be classified, with the inherent reliability in terms of safety.