Correlation of Velocity Prediction Program for Small Autonomous Sailboats

Abstract

Velocity Prediction Programs (VPP) are used to improve sailboat design and estimate performance. Using the concept of static equilibrium they rely on empirical relations derived from tank testing of a series of standard yacht hull shapes to estimate resistance. The VPP accuracy for non-standard hull shapes, such as SailBots, is a concern. Correlation of the VPP estimates to on-the-water measurements of a small autonomous sailboat was this project’s goal. Sixty-two data points were taken in winds ranging from 5 to 10.6 knots using the United States Naval Academy (USNA) SailBot, Mid-lenium FalcoN* and were compared to PCSail2.53, an Excel-based VPP developed from the Delft series and standard VPP code. From the analysis, it is concluded that the VPP makes an acceptably accurate prediction for boat speed within an average wind speed between 5 and 7 knots. At higher winds speeds, some points were within 95% confidence; however, the majority of on the water values were significantly slower than the VPP predictions.