Hints on the principles which should regulate the forms of boats and ships; derived from original experiments

Abstract

This paper discusses how to obtain eddymaking damping coefficients for slow drift oscillations of a moored ship in irregular waves. By deriving a simple expression for the standard deviations of the motions it is shown that it is not necessary to have great accuracy in predicting the damping coefficients. A single vortex method has been derived and used together with experimental U-tube results to discuss the hull parameter dependence of eddymaking damping. The single vortex method is shown to agree well with experimental results for midship sections without bilge keels. The effect of a bilge keel is strong at small KC-numbers and cannot be predicted theoretically by a simple single vortex model.