抄録
Hydrodynamic memory effect of wake vortices generated by a slender ship advancing with sinusoidal steering on the maneuvering motions in shallow waters is theoretically investigated. On the assumption of linear superposition, a calculation method is presented of the sway and yaw resoponses by applying unsteady slender body theory for prediction of hydrodynamic derivatives of the hull and rudder. For investigation of the memory effect, calculations are made of the sway and yaw resoponses for mathematical hull form including and excluding the effect due to the wake vortices. We find that the calculation results including the memory effect considerably differ from those excluding the effect in very shallow water such as the water depth to draft ratio h/d=1.1. This means that the quasi-steady treatment so-called assumption of slow motion derivatives, which is employed in usual meneuvering simulation method, is not hold good in such shallow water.
