Hydrodynamic forces and moment acting on a submersible surface ship in vertical motion

The submersible surface ship (SSS) is a ship that can avoid rough seas by going underwater. In order to submerge the SSS uses wings producing downward lift. The SSS, in submerged condition, keeps residual buoyancy for its safety. A prototype of SSS of which configuration is a hull, a pair of main wings and a pair of horizontal tail wings is designed and its model ship for tank tests is made. The circular motion test was carried out and hydrodynamic forces and moment in vertical motion were measured. The effect of submerged depth on the resistance and wings performances, and the effect of attack angle and pitch rate on the longitudinal and vertical forces and pitch moment acting on the SSS model are clarified. A method to estimate linear hydrodynamic derivatives is applied to the SSS model and compared with the results of tank test data analysis. The validity of the method and test data together with its effective utilization is discussed.