Ocean wave is an important marine environmental phenomena which influences the performance of a marine structure. This necessitates a detailed hydrodynamic study of the wave-structure interaction problem. In the present work the finite element method has been demonstrated as an effective tool to solve the complex linearised three-dimensional hydrodynamic problem. The developed software has been validated for regular bodies and applied to a multi-body (twin-barge) system. © 1995 IOS. All Rights Reserved.