Resistance of a Systematic Series of Semiplaning Transom-Stern Hulls

Abstract

YP 676 underway The results of a systematic series of small (5 ft) models of hulls typical of coastal patrol, training, or recreational powerboats are presented and discussed. Hull form parameters studied include length-to-beam ratio, displacement-length ratio, longitudinal position of the center of gravity and section shape (hard chine or round bilge). The effects of these parameters on the calm-water resistance and running attitude (sinkage and trim) over a range of speeds corresponding to waterline length Froude numbers from 0.10 to 0.60 were investigated in the 120-ft towing tank at the U.S. Naval Academy Hydromechanics Laboratory (NAHL). Experimental procedures and computer-based data acquisition and analysis methods used at NAHL are described. The experimental results as well as the cross-faired and nondimensionalized stillwater resistance trends are presented. Comparisons with other resistance prediction methods for hulls of the subject type are made. An example of the application of the resistance prediction to the new 108-ft yard patrol craft (YP) being acquired by the U.S. Naval Academy is included.