ON THE MEASUREMENT OF DIRECTIONAL WAVE SPECTRA

The directional resolving power of various directional instruments is examined. It is concluded that pitch/roll buoys have intrinsically poo r directional resolving power. This finding accounts for the broader d irectional spreading functions which have been reported for pitch/roll buoy data as compared to spatial array data. Improved instrument perf ormance can be achieved by increasing the number of measurement elemen ts in the measurement system. This is most easily achieved with a spat ial array of wave gauges. A rational method for the design of spatial arrays is presented. This technique allows the number and placement of gauges in an array to be determined so as to achieve the desired inst rument performance.