The choice of speed and clearance for RAS on 3D method

In this paper, a 3D source distribution technique is used to calculate the coupled motions between two ships which ad-vance in the wave with the same speed. The numerical results of coupled motions for a frigate and a supply ship have a goodagreement with the experimental results. Based on the 3D coupled motions of two ships, a spectral analysis is employed to clear-ly observe the effect of speed, clearance and wave heading on the significant relative motion amplitude (SRMA) of two ships.The method presented in this paper will be helpful to select suitable clearance, speed and wave heading for underway replenish-ment at sea(RAS).