4 ms·

Swinging about an anchor under the force of wind or currents would tend to make a circular arc.

• poooogles 8y ago
  Same for tides.
• dmurray 8y ago
  Normally back and forth on the downwind or down-current side of the circle, though. The chart shows it completing several circles.
  • windows_tips 8y ago
    The chart shows most of the data points on a small portion of the arc.
  • theresistor 8y ago
    Reversals are completely normal for cyclic tidal currents or sea breeze / land breeze cycles.