Still water resistance tests for a 2.3-m model of a Harley surface effect ship (HSC-SES), completed in August 2002, are presented. Few published studies of such a SES exist, and none provide useful measurements of the wetted surface area, which is needed to extrapolate results and predict full-scale HSC-SES performance. Here, estimates of wavemaking drag are made using free-surface elevations measured within the starboard air cushion. Separately, a numerical model, based on a fast-multipole accelerated boundary element method, is used to model fully nonlinear potential flow wave resistance of moving pressure patches, which correspond roughly to the HSC-SES cushions' footprint. The computed wave resistance roughly agrees with measurements taken during the towing tank tests.

INTRODUCTION

In recent years there has been broad interest in high speed ships, not only for special purpose military crafts, but also for fast passenger ferries and commercial sealift (McKesson, 1998). In this respect, one of the most promising concepts is the Surface Effect Ship (SES), which features an air cushion located, unlike hovercrafts, within a cavity built in a rigid hull. Reviews of SES designs can be found in Mantle (1980) and Yun and Bliault (1999). This work presents analyses of selected results of resistance tests performed in a towing tank, on a new type of SES design, the Harley SES. Experimental wavemaking drags are compared to those calculated in an idealized numerical model.

Harley SES

The Harley SES design was patented in 1996, by H. Harley, of Harley Shipbuilding Corporation (HSC) of Bartow, Florida. The HSC-SES, as it is referred to in this paper, is a catamaran ship built with rigid hulls (typically made of highly rigid and resistant carbon-reinforced composite material), having two air cavities (i.e., seal-less air cushions), each pressurized from airflow inlets at the bow (Fig. 1).

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