The NOAA Ship OSCAR DYSON is the First-in-Class fisheries research vessel designed and built for the National Oceanic and Atmospheric Administration"NOAA… for fish stock assessment. One of its most important contractual requirements was to achieve an underwater noise limit established by the International Council for the Exploration of the Seas "ICES…. The underwater noise limit has been specified by ICES over too large a frequency range and too small a resolution to allow for measurements with commercial grade test equipment. Modifications to the limit were made by NOAA which allowed the authors to develop a simple, deployable underwater measurement system. This system was then used to measure underwater noise from the OSCAR DYSON during sea trials in the Gulf of Mexico. The system consisted of a hydrophone array, signal conditioning and data acquisition hardware. The distance between the hydrophone array and the vessel must also be measured during the survey with the vessel in the acoustic far-field. Results from the far-field noise measurements were compiled and then compared to the ICES specification requirements. Self-noise from permanently mounted hydrophones in the hull were also measured during the survey. Finally, a comparison between the commercial system used by the authors and subsequent measurements performed by the U.S. Navy at their acoustic underwater test facility is made. These show good agreement at all but the lowest frequencies. © 2006 Institute of Noise Control Engineerig.

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The R/V HUGH R. SHARP is a general purpose research vessel that is owned and operated by the University of Delaware. It has been designed to achieve the International Council for the Exploration of the Seas (ICES) underwater noise limit for Fisheries Research Vessels. This paper describes the design process, construction details, and final results with regard to the acoustic design of this ship. Both compartment airborne noise and underwater radiated noise predictions were carried using a proprietary shipboard noise prediction program. Noise control treatments that were used include: vibration isolated machinery, double-stage isolated diesel generators, damping tiles, special acoustic insulation, and floating floors. After the vessel was completed a series of at-sea tests was performed to check compliance to vibration, compartment noise, and underwater noise. Two problems were discovered with underwater noise levels. One was related to a gearbox and the other was related to the propellers. A discussion of both issues and the final results are given in the paper. [Support provided by the University of Delaware, College of Marine Studies, in particular Mr. Matthew Hawkins, Director of Marine Operations.]

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