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

16 Broadway
Salem, MA 01970
01 + 978-741-1551
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MOTOR YACHTS

picture of Anson Bell
J&A was the acoustical designer for aluminum motoryacht, over 500 tons MCA. The boat grew in gross tonnage to be over 500 tons in the course of design, and J&A had to redo the insulation package to meet the more restrictive large yacht criteria. The boat was delivered in the spring of 2002, and runs very quietly.

picture of Aussie Rules
The motor yacht pictured here was one of the first all-aluminum, large 228-foot motoryacht's built in Australia. As such, the shipyard sought the expertise of J&A's engineering team to devise innovative, fire-rated insulation systems which would meet the latest MCA requirements calling for "steel equivalent" or greater protection of structural elements. J&A was able to execute a ground breaking design while maintaining the characteristic high degree of excellence of noise and vibration requirements.

picture of TatooshSometimes, for reasons beyond their control, J&A's up-to-date diagnostic tools cannot be used. This was the case on the occasion of this inspection aboard one particular large motoryacht seen here in dry dock. President Joe Smullin's keen sense of observation (not unlike that of an excellent medical doctor) and his wealth of knowledge detecting noise and vibration problems came into play. With only an educated "hand touch analysis" he was able to determine that the main machinery mountings were performing properly, but a rigid pipe support point carried notable vibration to the deck. Focusing on the complaint of vibration wobble, he knew from his wealth of past experience that shaft wobble would shake the whole human body when standing on deck at a rate that could be counted. Conversely, a propeller blade rate would be felt more in the lower body at a rate too high to count. Without the aid of instruments Joe hypothesized that shaft rate was the problem. And as the inspection progressed, it was observed that the starboard shaft was significantly out of alignment - very possibly the source of the problem. Joe and his team at J&A are always careful to rely on further measurements and testing before coming to the ultimate conclusions given to the client, but it is that wealth of knowledge and experience that the client has come to rely on and seek out when enlisting the services of J&A Enterprises.