Noise and vibration considerations in mega yachts

The modern motor-yachts between 30 m to 70 m with speed ranging from 14 knots to 35 knots are in vogue. With increasing demand for larger and faster mega yachts, higher noise and vibration levels have been experienced onboard these vessels. Potential owners simply demand a quiet and vibration free recreational space that is comparable to hotel accommodation. Such requirements are very taxing to the designer as the craft has to satisfy basic structural and safety criteria as well as the expanding design envelope for comfort and habitability. Vibration reductions entail an in-depth study of vibration sources and structural elements. Local vibration especially at the stern can easily fail a good yacht design. Often, noise reductions are not easy to achieve without costly counter-measures and these measures could affect the design considerably- for example, resilient mountings can result in weight increase, which in turn could cause propeller overloading. The present work outlines the current comfort criteria from a noise and vibration standpoint. Analysis methods available for noise and vibration predictions are reviewed and measures to reduce noise and vibration presented. A case study is given for noise assessments using both empirical methods and statistical energy analysis. General arrangement layout was reviewed based on calculation techniques. The performance of a selection of materials was also investigated, assessing their noise reduction capability. For vibration analysis, it was based on semi-empirical methods and finite element approach. These preliminary results should prove to be useful to the designer.