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A high-speed investigation was conducted to determine the hydrodynamic characteristics of a planing suface having an angle of dead rise of 20 degrees and horizontal chine flare. The data indicate that the planing characteristics at a given trim depend only on lift coefficient. The ration of center-of-pressure location to the mean wetted length can be considered approximately equal to 0.67 up to 18 degrees of trim. This ratio decreases with further increase in trim. Pile-up of water at the keep of the model was substantial at trims above 12 degrees. Friction drag is negligible at high trims. The resistances for trims at 18 degrees and higher, therefore, may be assumed equal to the load times the tangent of the trim angle.
In order to extend the range of available planing-surface data, the hydrodynamic characteristics have been obtained for a planing surface having a basic angle of dead rise of 200 at the keel and horizontal chine flare. This surface is representative of those used on present day flying boats. The wetted lengths, resistances, center-of-pressure locations, and drafts were determined at speed coefficients (Froude numbers) ranging from approximately 3.0 to 25.0, with the bulk of the data obtained at Froude numbers in excess of 7.0. Beam loadings were varied from 0.85 to 87.33. Keel-wetted-length-beam ratios were extended to 7.0 in all cases where excessive loads and spray conditions were not encountered. The data obtained indicate that, during high-speed steady-state planing, the planing characteristics are independent of speed and load for a given trim and depend only on lift coefficient. The difference between the chine wetted length and keel wetted length is constant for a given trim angle and the variation of this difference with trim is shown to be in reasonable agreement with theory. The ratio of center-of-pressure location forward of the step to the mean wetted length, for practical applications, can be considered a constant equal to 0.67 up to 180 of trim. A slight decrease in this ratio occurs with further increase in trim angle. The draft data indicate a pile-up of water at the keel during steady-state planing. Although negligible at low trims, this pile-up was significant at trims of 12 deg and higher. The drag data show that friction drag at trims of 18 deg and higher is negligible and that the resistances for those trims may be assumed equal to the load times the tangent of the trim angle.
The collected test data are presented in summary plots which are readily applicable for use in determining the lift, drag, side force, pitching moment, rolling moment, and yawing moment. An analysis is presented of the variation of these quantities with unsymmetrical planing parameters.