A Design Guide for Estimating Speed Made Good for a Sailing Yacht

This study develops a simplified comparative procedure for use in preliminary yacht design to predict Equilibrium sideforce, resistance, leeway angle and speed made good to windward for a canoe hull sailing yacht within specific form parameters on any of five standard series keels. These forces, angles and speeds are predicted for any yacht hull resembling one of nine models - ranging from light to medium-heavy length to displacement ratio - (190 to 351) - of the Delft Systematic Series for which there is numerical data. The forces are calculated at speed to length ratio of 1. 3 and heel angle of 30° to enable the designer to make use of existing comparative sail plan and rigging data. The five keels of varying aspect and area ratio, spanning current design practice, are part of a matrix developed at the Davidson Laboratory. In this paper, a canoe yacht hull form similar to Model 7 of the Delft Series is tank tested on 3 Standard Series keels and compared to results obtained from testing a 5.5 m hull, which is similar to Model 8, on the same keels. A prediction procedure is developed and checked against test results. A few Equations, selected values from included tabulations, a calculator, pencil and paper will yield quantitative information for the yacht designer in the selection of a keel for the hull of a sailing yacht.