Impact of heavy biofouling on a nearshore heave-pitch-roll wave buoy performance

The impact of biofouling is investigated on the accuracy of the records of a wave buoy moored in shallow water. The effects of biofouling on the vertical and horizontal motions of the buoy are analyzed through check factors. Regarding the heave motion, the most critical frequencies of the power spectrum are identified, and selected to run CFD simulations to further evaluate the hydrodynamic impact of heavy biofouling. The time evolution of check factors allowed identifying the increase of accumulated mass, which became more critical in the last two months of the period of observation, associated with the modification of heave, surge or sway, and pitch or roll signals. The top high frequencies with periods below 3s are the most affected, with attenuation of the vertical motion. The spectrum at mid frequencies up to 15s is not modified and a small effect at low frequencies is reported. The impact of biofouling on the bulk wave parameters derived from the heave motion is minimal. Small differences of 0.4% up to 1.7% are found for significant wave height, associated with underestimation of short length waves, and no difference was noticed on the estimation of peak period.