A wave height measuring instrument is described which measures the height of water surface waves by means of sonic ranging technique in air. This system is advantageous for wave amplitude measurements from a moving towing carriage since the sensing elements or its supports do not disturb the water surface.
The design operation range of the instrument is 2-in. to 2-ft wave height. The accuracy of measurement depends on the incremental slope of the water surface at the point of measurement. An intrinsic error of +/- 0.8 per cent average over the wave would occur for a 2-ft wave with a slope at mid-height of 0.2. This error increases to +/- 3.2 per cent for a 2-in. wave of the same slope. The error is much reduced for both these conditions with less steep waves.