Characterising the acoustic footprint of Australia's new research vessel RV Investigator

The RV Investigator is Australia's new noise quietened Marine National Facility (MNF) vessel built to comply with the DNV silent-R specification. This radiated noise specification was based on the ICES 209 CRR specification designed with the main goal of minimising vessel avoidance for fisheries surveys. Noise quietening was specified for RV Investigator to improve the acoustic detection of instruments and reduce the vessel's noise footprint on the environment for research activities. Traditionally DC propulsion motors are used to achieve radiated noise compliance; in this case AC propulsion motors have been used. Initial noise measurements show the RV Investigator is 20 dB (factor of 100) quieter than the previous MNF vessel, RV Southern Surveyor which will significantly improve acoustic instrument performance. The new acoustic systems on the RV Investigator range from sub-bottom profilers, Doppler current profilers, multi-frequency and multi-beam water-column echo-sounders and low to mid frequency multi-beam bathymetry echo-sounders.