An Ocean Wave Measuring Buoy

The author describes the design, construction, and performance of a surface wave-following buoy that can measure the directional spectrum of 0.06 to 0.5 Hz ocean waves with an accuracy of 10, and an angular resolution of around 90 degrees. The buoy is disc shaped, 1.5 m 5 feet in diameter, weighs 150 kgm 300 lb, and is completely self-contained. Wave height is measured by an accelerometer mounted on the inner gimbal of a vertical gyro, wave slopes by the tilt of the buoy about the gyros vertical axis, and buoy heading by a gyro stabilized compass. Data from the transducers are digitized and recorded on computer compatible magnetic tape. Wave spectra are calculated from the data by computer. The accuracy of the measurements is verified by calibration in a wave tank, and by the internal consistency of the data.