Inflatable offshore fender barrier structures are anti terrorist structures that function primarily to either stop an impacting vessel, incapacitate its crew or delay terror events. In a quest to ensure effective utilization of the compressed air in the barrier which functions to increase barrier stiffness, dissipate impact energy and potential for high vessel instability after impact; a new design of the structure is proposed in this paper. Its dynamic response under a vessel of 0.16MJ of kinetic energy impacting on the barrier was assessed using the finite element method. Fluid structure interaction of the structure was achieved using the Eulerian-Lagrangian formulation and the enclosed air in the barrier structure was modelled using the 'surface based cavities' capabilities in ABAQUS. The results indicate desirable response of the structure following impact by the vessel. This is important as low initial inflation could be utilised for the proposed design compared with the current design and the likelihood to delay terror events is maximized.