Wide ranging study on the motions of SWATH ships with and without forward speeds

Using physical and theoretical models for the seakeeping analysis of SWATH ships, this paper reports a comparative study between single and tandem strut SWATHs, and between circular and rectangular hulled SWATHs. The models are analysed both stationary and travelling in waves from an arbitrary heading, ie, head, bow quartering, beam and following seas. The effect of design changes, such as number of struts per demihull, hull form, spacing between the two demihulls and the introduction of stabilising fins, on the motions is assessed. Advantages and disadvantages are clarified to provide some design recommendations to the SWATH designer. This paper demonstrates that the present analytical tool gives excellent correlation with a wide range of experimental results. Finally, some advantages of a SWATH having hulls with rectangular cross section with rounded corners are emphasised based on the comparative study with the U.S. Navy KAIMALINO within the criteria given.