Abstract
A combination wind vane and anemometer model (Marine Speedovane) is tested in wind tunnel, as to its mode of oscillation and variation of rotational speed in pitching or rolling motion with wind on. According to this model experiment the pitching motion of period of 8 seconds (actual weather ship's value) has nothing to do with the indication of the wind vane, but it seriously affects the rotational speed of the anemometer windmill, which is oscillating with the same period as that of the pitching motion and with a certain phase lag. The mean rotational speed is found remarkably lower than that without pitching at the same wind speed. In the rolling motion of the same period, however, the mean rotational speed of the anemometer windmill agrees well with that without rolling at the same wind speed. No definite periodicity and phase lag of the rotation are found in this case except a certain band width of fluctuations.
