Hydrodynamic Performance of an S-SWATH Ship in Calm Water and Waves

An unconventional SWATH (Small-Waterplane-Area-Twin-Hull) ship is introduced, named S-SWATH, which is a catamaran with twin hulls that are slightly curved in an S-form and arranged at a mean yaw angle but mirror symmetric to their common longitudinal center plane. Based on the “shallow-channel superconductivity” theory, proposed by Chen and Sharma, in this paper a more accurate viscous flow theory, solving the Reynolds-averaged Navier–Stokes equations (or RANS equations), is used to study the hydrodynamic performance of the S-SWATH ship. The simulation results of calm-water resistance and motions in waves are presented. In comparison with a benchmark conventional SWATH ship, which features a typical torpedo-shaped body, the simulation results prove the effectiveness of the S-shape design. On one hand, the S-SWATH ship inherits the major advantages of SWATH ships, such as the superior ride quality, acceptable acceleration levels for human habitability and therefore comfort and overall superior seakeeping characteristics. On the other hand, the S-SWATH ship has much less low-speed drag than its conventional SWATH counterpart, and comparable total drag at high speeds.