I am using SoundDown in my engine room. It and Whispermat are the standard
sound insulation for marine engine compartments. Panda, Onan and other
genset makers use it in their cabinets. Basicly they are 1/2 to 3/4" of PVC
acustical foam either side of a 1 lb/ft lead filled vinyl sheet. It is
appiled with spray on adhesive and welded or epoxied spikes and caps.

The general recomendation is to design baffel boxes so that the air has to
make at least one 180 turn so there is no direct path and the baffel should
be lined with the acustical barrier. Being cooled by a seawater heat
exchanger my diesel doesn't need quite that much vent area but here is an
example. The 28"wide x 6"high vent is on the back wall of the engine
compartment. The baffel box is 30"D x 8"H x18"D. It is oversize because
the first chamber is lined with 1.25" sound barrier. (I hope this comes out
in fixed width font.)

+----------------+
| |
| | |
| | Vent
| +--------+
Engine Compartment

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Ignoramus1606" wrote in message
...
On Thu, 20 Jan 2005 20:18:45 -0500, Glenn Ashmore
wrote:
If you have to buy it. Why not look at SoundDown or Whispermat? They
are
about the twice the price you are lookimg at but is made for the purpose
and
far more effective and 1/3 the weight..

I will check them out. Do you have experience with them?

Just lead fixed to the inside of the cabinet will not be all that
effective.
Lead needs a decoupling layer between it and the cabinet sides to
prevent
mechanical transmission of the lows and an absorbent layer in front to
take
care of the higher frequencies. Also the smallest crack will make the
whole
effort almost worthless.

Glenn, can you elaborate on this last point (about cracks invalidating
this). I will need an air opening for intake of cooling air, which
will be exhausted from the back. It has to be at least 2 square feet,
but I can somehow baffle it.

Again, I would love to be dissuaded from this idea of buying lead, if
in fact it is a wrong idea. I do not want to waste money.

i


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