Above is sample plot of data received from ADCP 1 of current speed plotted against time.

ADCP stands for acoustic Doppler current profiler with Bottom Tracking. These instruments use pulses of sound (at frequencies too high for humans to hear) to sense how fast the tidal currents are moving. We need to know how fast the currents are moving such that we can determine how much power we can produce with the turbine. Operating the turbine in faster currents will produce more power. Notice how the currents change direction twice per day as the tides ebb (flow from estuary to ocean) and flood (flows from ocean to estuary). Approximately twice per month one will notice very fast currents approximately every other week in what are called spring tides. During the weeks opposite of the spring tides one will notice slower tidal currents in what are known as neap tides.