To date, one of the difficulties with wave energy devices is modulating the power transfer from the waves to the generator. In wind turbines, this is achieved by turbine pitch control, leading to the ubiquitous flat power curve. Recently, a wave energy converter, having moveable vanes, has been developed by the National Renewable Energy Laboratory (NREL) in the US. This paper described the development of a compact hydrodynamic model for the NREL device, based on multiple linear hydrodynamic modelling (Murray-Smith and Johansen, 1997), which can be used to model the hydrodynamic behaviour of the device across its full operational spectrum of vane angles. To show the utility of the model, we demonstrate a flat power curve for the WEC, using the vane angles as a control input.