Measurement of radiated underwater noise from a small research vessel in shallow water

The impact of man-made underwater noise on the marine environment has in recent years received increased attention from regulatory authorities, as evidenced by its inclusion in the Marine Strategy Framework Directive (MSFD) of the European Union (EU). Radiated underwater noise from ships, primarily resulting from propeller cavitation, has for many years been understood to be one of the major contributors to ambient ocean noise. Civilian research in this area has to date been relatively limited; standards covering the measurement of radiated noise from ships in deep water and data analysis procedures have only recently been published by national and international standards institutes. Less attention has so far been paid to the measurement of radiated noise from ships in shallow water environments. This is of interest as shallow water areas are more likely to be used by civilian researchers due to the logistical problems involved in undertaking trials in deep water. The issue of shipping noise has been identified as one requiring further research, indicated by the recent funding of several large collaborative projects by the EU (see for example the SILENV, AQUO and SONIC projects). This paper presents ship radiated noise data measured using a three hydrophone array during a recent sea trial undertaken as part of the SONIC project