The longitudinal vortex, which originates at the bilge part of full form ships, usually becomes a major part of viscous resistance. In this paper, the energy saving device, which is developed in order to utilize the hydrodynamic energy of longitudinal vortex, is discussed. At first, the basic experiments using two rectangular hydrofoils have been done in order to ensure the energy saving mechanism of this energy saving device called NKK-VENUS (Vortex Energy Utilizing Surfaces), then energy saving effects of NKK-VENUS were investigated using the three types of model ships by the towing tank tests. In these towing tank tests, NKK-VENUS was also used together with the stator type energy saving device NKK-SURF Bulb. At last, the energy saving effects and the interactions of these two energy saving devices are also discussed. In conclusion, much more energy saving effects can be obtained by combining these two types of energy saving devices.
