The paper presents a numerical investigation of the wave-structure interaction using a hybrid model, qaleFOAM, which combines a two-phase Navier-Stokes model (NS) and the fully nonlinear potential theory (FNPT) using the spatially hierarchical approach. The former governs a limited computational domain (NS domain) around the structures, where the viscous effects may be significant, and is solved by using OpenFOAM/InterDyMFoam with a modified solver for the six degrees-of-freedom (6DoF) motions of rigid bodies. The latter covers the rest of the domain (FNPT domain) and is solved by using the Quasi Lagrangian Eulerian Finite Element Method (QALE-FEM). In the numerical simulation, the incident wave is generated in the FNPT domain using a self-correction wavemaker and propagates into the NS domain through the coupling boundaries (inlet of the NS domain). An improved passive wave absorber is imposed on the outlet of the NS domain for the wave absorption, whereas a new module for solving six-degree-of-freedom structural motions is also applied. The accuracy of the qaleFOAM on modelling wave-structure interaction is preliminarily investigated in terms of both the wave propagation and the responses of the structures. Finally, the qaleFOAM is applied to the CCP-WSI Blind Test and some results are presented for demonstrations.