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

16 Broadway
Salem, MA 01970
01 + 978-741-1551
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picture of sailboat Ranger


To keep sailing the yacht, pictured above, within J-class racing limits, J&A Enterprises designed noise controls optimized for lightweight. To reduce exhaust system noise, custom exhaust silencers were designed and built by J&A's affiliate, Soundown. Special silencers were developed for the engine room ducts, designed to meet fire protection requirements and meet noise attenuation goals with a single treatment. Then the engine room insulation was optimized for good noise reduction with minimum space and weight, while still complying with MCA and Lloyds safety requirements. The final construction of this Danish built yacht, realized additional weight savings compared to design estimates, while still meeting the objectives for quality of finish and noise reduction. This allowed for the weight saved from the interior to be added as ballast in the keel, further improving the sailing performance of this beautiful yacht.

This is a 175 foot aluminum sailing yacht built by Alloy Yachts. During sea trials, the J&A engineer was assured that the pitch at which the propeller was operating was the design pitch. J&A suggested that the pitch be increased which was found to be a more optimum setting for noise mitigation. Also, J&A recommended grinding the anti-singing edges along the entire trailing edge of the blade to reduce noise. J&A's experience with propellers is that an effective anti-singing edge should be executed by chamfering the suction face of the trailing edge, not the pressure face.

picture of sailboat Salperton