Near-Field Hydrodynamics of a Surface-Effect Ship

A consistent near-field linearized potential-flow analysis of a surface-effect ship traveling at a steady speed in laterally restricted water of finite depth is described. Additionally, the influence of seals, in terms of their drag and lift on the vessel, is included in the theory. The predicted results include the sinkage and trim, the resistance components, and the profile of the free surface of the water along the sidehulls. These predictions are compared with the corresponding results measured on a towing-tank model. It is demonstrated that the inclusion of the influence of the seals substantially improves the numerical predictions for the sinkage and trim. Good agreement is achieved for the total resistance provided a frictional form factor of 1.306 is used. The correlation between theory and experiment for the profile of the free surface is high, except in the vicinity close to the bow, where the nonlinear effects in that region are strong.