A quiet operating power boat adds significantly to the pleasure of recreational boating. Boating is most enjoyed in areas with low ambient sound levels and boat owners want to be a part of that environment.The quieting of a power boat cannot be adequately performed when it is treated as an engineering adjunct or an after thought. In the building of a power boat no one manufacturer has the control over all the characteristics of the final product. Quieting has to be the product of a well organized and coordinated design effort between the boat builder and the engine manufacturer.At the onset, viable sound level objectives must be established. Potential sources of noise must be identified and carefully analyzed.This paper will present some techniques for the establishment of attainable sound levels both in and out of the boat. It will also delineate techniques that can be used to analyze noise sources and noise transmission paths.Finally a system is developed for transmitting design aids to the boat builder. These aids will assist the builder in employing the most cost effective selection of materials, devices and designs for the sound level reduction of a power boat.