Factors affecting the underwater noise of commercial vessels operating in environmentally sensitive areas

Underwater noise radiated from commercial vessels is becoming a concern for cruise vessels and work boats operating in environmentally sensitive areas. This paper assesses the primary noise sources and transmission paths controlling the vessel's signature. The relative contribution of machinery induced noise (diesel, gas turbine) and propulsor (propeller, water jet, azipod) induced noise will be highlighted. It is necessary to understand which operating conditions and systems control the vessel's signature in order to optimally design quieter ships or to abate the noise from existing ships. The effectiveness of various treatment types will be explored. A comparison will be made of the effort required to quiet a 'purpose built' research vessel such as NOAA's Fisheries Research Vessel and a commercial vessel that wants to be environmentally friendly.