An Experimental Analysis of the Effects of Steps on High Speed Planning Boats

The hard chine, deep-vee hull form has been used in a wide variety of commercial and naval applications for a number of years. The hull form offers advantages in stability, speed, and wide beam for large cockpit areas. There are also several disadvantages associated with the hull form, most notably the large motions and accelerations in a seaway. In recent years the high speed boat racing community has adopted transverse steps in the after bottom surfaces of the hulls to introduce air pockets and reduce drag. The size, number, and location of the steps have varied, but the concept of stepped-hulls has become a standard for high speed craft. In several navies throughout the world stepped-hull planing boats have been introduced in the littoral warfare communities with some apparent success.