Abstract: Objectives When two floating bodies work side by side, the close spacing between them can cause hydrodynamic interactions, resulting in large wave oscillations in the gap and motions of the two bodies, seriously threatening the safety of the operation.Methods This paper uses the hybrid two-way coupled field-domain decomposition method to establish a numerical wave tank, where the incident wave part is computed explicitly, and the diffraction and radiation parts are solved on a two-way coupled potential-viscous flow field. Further, the overset technology is applied to simulate the body motions.Results The computational method is first validated by simulating the hydrodynamic resonance in gap of two floating bodies in same dimension , and the numerical results are compared with experimental data.Conclusions The results show that the two bodies move in phase for low-frequency waves, resulting in smaller relative motions between them. On the other hand, under high-frequency wave conditions, the two bodies move in an inverted phase, enlarging the relative motions. Further, when the larger floating body is located upstream, there is a significant shielding effect on the downstream small body.