Wave flume experiments indicated that for waves propagating on quiescent waters the sensor's performance improved (i.e. the difference Delta P between the average hydrostatic and measured pressures was small and positive) when the inlet was at the centre and flush with a large, thin, smooth circular horizontal end-plate. In this case, isolation of the pressure inlet from the separated flow and vortices shed by the sensor housing was partly responsible for the observed improvement. Another reason for improvement seems to have been a much reduced value of the wave-induced oscillatory boundary layer flow, in the vicinity of the pressure inlet, as compared to the mainstream oscillatory flow. The sensor's performance wa better for the case of waves riding on currents as the Delta p in this case was the sum of a positive Delta p for currents alone and a negative Delta p for waves alone. This result is of special significance to tidal measurements of coastal waters in which waves propagate on tidal currents.