Underwater sound of rigid-hulled inflatable boats

Abstract

Underwater sound of rigid-hulled inflatable boats was recorded 142 times in total, over 3 sites: 2 in southern British Columbia, Canada, and 1 off Western Australia. Underwater sound peaked between 70 and 400 Hz, exhibiting strong tones in this frequency range related to engine and propeller rotation. Sound propagation models were applied to compute monopole source levels, with the source assumed 1m below the sea surface. Broadband source levels (10–48 000Hz) increased from 134 to 171 dB re 1μPa @ 1m with speed from 3 to 16m/s (10–56 km/h). Source power spectral density percentile levels and 1/3 octave band levels are given for use in predictive modeling of underwater sound of these boats as part of environmental impact assessments.