We used that on the engine box of a racing sailboat we built.  Surrounded
an Izusu Diesel aux. motor that was right dead center in the main cabin of
this IOR design.  It sorta worked, but you couldn't talk in a normal voice
below when powering along and it was pretty heavy...Pricey, too.
  Not something I would put in a Vanagon...unless it was powered by a TT
Porsche motor or something...

  Don Hanson

On Thu, Apr 8, 2010 at 9:19 AM, David Beierl <dbeierl@attglobal.net> wrote:

> At 10:46 AM 4/8/2010, Alistair Bell wrote:
>
>> Supposedly the best thing, after applying the panel dampener is a,
>> (oh shoot, I forget the term), a "de-coupling sheet"  - heavy vinyl
>> sheet that absorbs the vibrations, then some foam type insulation
>> (closed cell foam best in the van, for obvious corrosion reasons).
>>
>
> You can get multilayer lead or lead-substitute silencing material
> from marine suppliers, intended for lining engine boxes/rooms.  It's
> pretty spendy IIRC.
>
> When I was a lad the Navy was using a composite substance for
> submarine quieting -- they called it RAL, or rubber-air-lead.  I
> found a piece of it once and asked my dad about it.  It was maybe 3/4
> or an inch thick, bendable but not stretchy, black rubber-stoffe
> impregnated with little flattened voids and similar-sized flakes of
> lead.  A bit dirty to handle; I probably took five years off my life
> playing with it.  I'm guessing it was cast in some way and then
> rolled to thickness.  No idea whether they still use it.
>
> Ah ha.  Here's a milspec for the version that superceded what I'm
> talking about.
> <http://www.tpub.com/content/MIL-SPEC/MIL-R/MIL-R-23074C/index.htm>.
> This type is made with molded grooves filled with #8 lead shot,
> weighs about 5 psf.  It was "inactivated" in 1998 -- obsoleted?  I
> don't want to pay USD24 to read one page of bumf.
>
> Yours,
> David
>