The article discusses performance of a power module in a wave-powered navigational buoy developed by National Institute of Ocean Technology. The power module of the buoy consists of an impulse turbine and a generator. Both unidirectional and bidirectional impulse turbine were tested for their performance. The article describes the selection, performance assessment tests and experimentation on these power modules carried out in the laboratory and in open sea trials. It was observed that unidirectional impulse turbine gave better performance than bidirectional impulse turbine for a given range of flow coefficient and pressure drop across the turbine. The performance of the wave powered navigational buoy in the open sea trials has given confidence on its use as a product and has also led to knowledge enhancement for scaling up floating wave energy devices.