Trim effect on the resistance of sailing planing hulls

• Measurement of the resistance of a new type of vessel
• Effect of the crew position on the resistance of a light-weight vessel.
• Uncertainty analysis for high-speed resistance measurements in small towing tank

Sailing skiffs are light-weight high-performance small boats of growing interest in competitive sailing. The present paper presents towing tank tests performed on the Aura skiff, which was a candidate for the 2016 Olympic games. Resistance, sink and trim were measured for different longitudinal positions of the crew weight and for Froude numbers (based on the boat׳s length over all) ranging from 0.30 to 1.03. For each test, detailed analysis of the measurement uncertainty was performed. The measured resistance was found in good agreement with the resistance computed with established empirical formulations developed for planing hulls. It was found that the optimum crew position moves from forward to aft when the Froude number increases. An incorrect longitudinal centre of gravity led to a maximum resistance penalty at Froude number around 0.4. These trends are in agreement with the sailor׳s experience and with measurements performed by other authors on large vessels.