The Effects of Streamlined Rigging on Sailboat Performance

The design of sailboat rigging influences the yacht’s performance through the change in vertical center of gravity, windage, and ability to control the shape of the rig. In the past, designers have attempted to minimize this drag through the use of streamlined shapes, because it is well known that a streamlined section has much less drag with respect to a circular shape. Streamlined shapes have not been commonly used in practice probably because they are difficult and costly to manufacture. Also, some shapes may exhibit worse vortex induced vibrations (VIV) when compared to circular rigging. New manufacturing capabilities using composite materials have suggested that streamlined shapes be reconsidered for yacht standing rigging. This paper investigates the influence of two cross-section shapes of the rigging on the performance of an IMS40 sailing yacht. A modified NACA foil and a circular section are selected for the comparison, and both shapes are analyzed with numerical simulations and physical experiments. We study the change in sailboat performance due to the different aerodynamic and material properties of the rigging. A velocity prediction program (VPP) is used to quantify the performance change by comparing the time required to sail two different race courses.