Resistance of the Submerged Bodies Running Near a Free Sarface

Since 1970, semi-submerged containers have been investigated in the Ship Research Institute. The knowledge of the hydrodynamic characteristics of a shallow-running flat submerged body has become essential for the hull form design of a large semi-submerged ship. Through the study on separation of the resistance components of three flat submerged bodies and an elliptic body of revolution, following problems are discussed.a) Unexpected large resistance of shallow-running submerged bodies (Fn>0. 25) results from generation of the vortices behind ship.b) The resistance due to the vortices is obtained as viscous resistance depend on Froude number because of the vortices behind submerged bodies mainly originated in the current of free waves.c) Wave making resistance of submerged bodies is seriously affected by the vortices.d) Flow symmetrization between the up and down side of the shallow-running flat submerged bodies significantly contributes to reduce the resistance.