Deep-Water Field Evaluation of the NDBC-SWADE 3-m Discus Directional Buoy

Abstract

This paper presents the results of an experiment designed to assess the directional spectrum resolution qualities of the pitch-roll-heave National Data Buoy Center-Surface Wave Dynamics Experiment (NDBC-SWADE) 3-m discus wave directional buoy in deep-water conditions. Wave frequency spectra and wave directional spectra measured by the buoy, moored in about 415-m water depth, are compared to similar measurements obtained from a wave staff and a biaxial current meter fixed to the nearby Bullwinkle platform (Gulf of Mexico). Both buoy and platform equipment operated simultaneously from 0000 UTC 29 May 1989 to 0100 UTC 24 June 1989. The analysis revealed that the buoy surface displacement energy spectra (estimated from heave acceleration) agree well with the platform spectra. Comparison of mean direction and directional width parameters is favorable considering the large variability of those estimators. Discrepancies are reduced when records of significant wave height less than 1 m are eliminated.