A measurement system is required for the assessment of the structural and kinematic response of a free-running model, either at model or full scale. Tethered and optical measurements systems used in towing tanks and wave basins are unsuited to this application. A system of wireless sensor nodes with synchronised video capability has been developed which allows rigid body motions and three-axis accelerations to be obtained by a single nine degree of freedom sensor node whilst the structural deformation of the hull girder can be obtained from a minimum of three nodes in parallel. The system performance was assessed in a controlled towing tank environment in comparison to a tethered system, using three nodes mounted on a flexible, four segment model hull. Measurements from the wireless system were comparable to the tethered results with the same degree of accuracy. Further tests showed a single node to produce comparable measurements to an optical system. The additional synchronised video capability allows a visual image of an extreme wave encounter to be correlated to the magnitude of the responses experienced. Practical advantages of the wireless system demonstrate its viability for acquiring high quality model data; further development should allow its application to full scale.