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

• Measurements of radiated noise from a ship in shallow coastal waters were undertaken.
• Experimental and data analysis procedures used were in line with international standards.
• An increase in level with ship speed is observed over a wide range of frequencies.
• Practical issues associated with underwater noise measurements at sea are discussed.

The impact of man-made underwater noise on the marine environment has recently received increased attention from regulatory authorities, as evidenced by inclusion in the Marine Strategy Framework Directive (MSFD). 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 associated 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 (e.g. the SILENV, AQUO and SONIC projects). This paper presents ship radiated noise data measured using a three hydrophone array during a sea trial undertaken as part of the SONIC project.