Forced Oscillation Tests and Motion Measurements with a Small Waterplane Area Twin Hull Ship

摘要

In the search for a vessel with outstanding seakeeping characteristics, such as smooth motions and high sustained speed in a seaway, attention has been drawn to the SWATH concept (SWATH stands for Small Waterplane Area Twin Hull). These ships have the major part of their buoyancy fully submerged in two large cylinders. On these cylinders two surface piercing struts are placed which support the cross structure high above the water. Two extensive computer programs for the calculation of the motions of a SWATH in regular waves have been developed. In order to validate the results of these computer programs and to gain more insight in the behavior of a SWATH in waves the Ship Hydromechanics Laboratory of the Delft University of Technology decided to perform an extensive series of experiments with a SWATH model. The experiments consisted of two parts. First a forced oscillation test in the four principal modes of motion of a rigid SWATH model for the determination of the hydrodynamic coefficients, which form a basic element in the calculation of the motions in waves and secondly the heave and pitch response of a SWATH to both head and following waves.