J
& A Enterprises, Inc. Noise and Vibration Control
Engineers
16
Broadway
Salem, MA 01970
01 + 978-741-1551
MOTOR
YACHTS
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.
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.
Sometimes,
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.
MOTOR
YACHTS 
Sometimes,
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.