An Excel Velocity Prediction Program has been developed to allow for rapid evaluation of yacht performance at the initial design stage. The required input consists of only the basic hull and sail dimensions. Empirical equations, based on these basic dimensions, are used for initial estimates of required hull parameters. As the design progresses the user can easily replace these default values with refined estimates or actual values. Because of its simplicity, and short turn around time, the program has been used as a teaching aid at the University of Michigan. Reconstruction of the program, PCSAIL, may be made with equations and other information provided in the Appendix.
The Excel "Solver" has been found to be a reliable means of finding the equilibrium boat speed and heel angle. It seeks the maximum boat speed by adjusting the sail flattening factor, F, and reef, R, and the lateral location of the "movable crew." In the case of a hinged centerboard, or dagger- board, it will also adjust the draft for maximum boat speed.
For sloop rigs the program will also take in the jib and set the spinnaker, at the appropriate wind angle, in order to gain maximum boat speed. The program plots the speed "polar," and velocity made-good, and determines the tacking angles.
