The basic concepts and underlying assumptions of Statistical Energy Analysis (SEA) are reviewed. Using coupled simple oscillators as models for resonant modes, power balance equations are derived. Equipartition of energy among modes within a subsystem, and strong versus weak coupling between subsystems are discussed. Input requirements for exercising SEA power balance equations are defined and methods of obtaining the required input are outlined. Examples of the applications of SEA are presented and discussed.

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This paper examines the hydroacoustic processes involved with "singing propellers" aboard marine vessels. Methods are presented to determine the potential for a resonant response of a propeller to a vortex shedding excitation—a phenomenon known as "singing." Methods are provided to determine the likely shedding frequency and structural natural frequency for propeller blades. Diagnostics procedures to determine the presence of singing are explored. Measured and theoretical differences between the blade's natural frequency response in air and in-water are explored. Treatments are identified to change the vortex shedding frequency or to de-tune the structure. Case histories are detailed showing the potential magnitude of the problem and effective solutions.

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.