Improvement of the heave motion of a semi-submersible platform with damping sheets subjected to sea waves

In this study, the damping sheets were attached to a semi-submersible platform to mitigate the heave motions. We first examined a typical GVA4000 semi-sub under a monochromatic linear wave train in deep water. an analytical method based on diffraction theory was used to determine the heave motion response. The results revealed that the analytical results show good agreement with available experimental data. Then, the damping sheets were attached to the pontoons of the GVA4000 semi-sub under study. The heave motion response was evaluated with the changing numbers and widths of sheets under constant thickness in different sea waves conditions. The results showed that with increasing damping sheet width, the heave motion response is improved. Moreover, the heave natural frequency of semi-sub is shifted far away from the monochromatic wave frequency, so, the resonant phenomenon significantly decreases. Based on the proposed method, it is concluded that the solution to reducing heave motion response of the semi-submersible platform is simple, effective, economical and practicable.