Frequency domain analysis of hydrodynamic characteristics of mariculture ship with truss and plate frame hybrid structure

In order to study the hydrodynamic performance and motion amplitude response characteristics of the mariculture ship composed of truss structure and several floating bodies with plate and frame structures, we calculated the hydrodynamic characteristics of the ship in frequency domain based on the three-dimensional potential flow theory and Morison equation. Then we obtained and analyzed the hydrodynamic parameters and motion response of the mariculture ship. The results show that the additional mass and radiation damping of the mariculture ship were sensitive to the change of frequency, and the sensitivity was obviously different in the movement of the mariculture ship in different directions, and the additional mass and radiation damping of the three rotations were larger than those of the translations, which were both closely related to the structural shape of the mariculture ship. Under the action of incident waves in every direction, the first-order wave force of the mariculture ship increased at first and then decreased with the increase of frequency, and the first-order wave force curve tended to be stable in the high frequency section under the action of incident waves in different directions. However, there was a big difference in the middle and low section. Under the action of high-frequency and low-frequency excitation, the motion response of the mariculture ship was small, but the resonance occurred when it moved in the medium and short period regular waves. The surging and pitching were the main motion modes when ship was with follow wave or head wave condition, and roll and heave motions were the main motion modes in bean wave.