J & A Enterprises, Inc.
Noise and Vibration Control Engineers

16 Broadway
Salem, MA 01970
01 + 978-741-1551
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Buquebus: Sound Reduction Advances

    The effort to eliminate sound and vibration signatures is particularly critical in the passenger/cruise vessels markets for many reasons.  A noisy, shaky ride is sure to alienate passengers and hurt business prospects, but adding layer upon layer of sound-deadening materials adds critical weight factors and effectively reduces a vessel's profitability as well.  In creating the 52-knot Buquebus, builder and designer took extra steps to ensure that noise control was judiciously yet adequately placed.  Sound measurement trials were completed with noise measurements taken by noise consultants, J & A Enterprises Inc., at various locations throughout the vessel with the microphone held at approximately five ft. above sole.  At an early stage in the design, NGA and Derecktor decided to pursue a philosophy of not fitting any sound insulation, other than the inherent sound deadening provided by fire insulation, until noise measurements could be completed during trials.  This simple approach allows for noise reduction to be applied exactly where it is required, with a potential saving in the weight of additional noise insulation that may not have been effective.  Average noise levels within the lower and upper passenger saloons during initial trials were 82 db(a) and 76 db(a) respectively.  This trial also showed noise generated from the hull bottom with the vessel at high speed (I 15 db(a) in forward voids) was contributing significantly to the interior noise levels.Therefore, following this trial, two forms of noise reduction were installed.  Polymer panels were applied to areas of the bottom structure to provide mass damping of these panels and secondly, a layer of sandwich construction insulation with a high-density middle layer was applied across the underside of the deck in way of the passenger saloon.  The combined effect of these treatments was to reduce the average noise level in the lower deck passenger saloon to 75 db(a) and to 72 db(a) in the upper deck saloon.

Maritime Reporter and Engineering News, September 1999, pg83.