Re: Help with outboard sound-proofing
Car audio shops (the ones that sell and install the very annoying bass
"boom boxes") carry a number of sound-deadening materials, from foams
to sprays to rubber-like sheets. You can get a lot of information
from the installers on sound absorption. Sounds odd, but these fellows
have found that if the car's panels cannot vibrate, the sound they are
looking for comes through better; they have become *very good* at just
a technology that we need.
Cheers/Don Carron
Dana Audio... mfgr of annoying auto audio bass subwoofers :-)
"boom boxes") carry a number of sound-deadening materials, from foams
to sprays to rubber-like sheets. You can get a lot of information
from the installers on sound absorption. Sounds odd, but these fellows
have found that if the car's panels cannot vibrate, the sound they are
looking for comes through better; they have become *very good* at just
a technology that we need.
Cheers/Don Carron
Dana Audio... mfgr of annoying auto audio bass subwoofers :-)
In a message dated 6/9/03 9:52:25 AM Central Daylight Time,calex@...
writes:
any lead in them, but have a sheet of PVC sheet sandwiched between two foam
layers. They claim it provides "dramatic noise reduction compared with single
layer foam barriers." I can't say I find this ad copy claim particularly
enlightening.
One side is faced with shiny aluminized mylar film and the other has
peel-and-stick adhesive. The foam layers are different in thickness and perhaps
composition. I infer that the shiny side is supposed to face the source of the
noise. I haven't tried it yet, so can't speak to how effective it is.
The stuff is pretty expensive. 32" by 54" by 1" goes for $90 + S&H and is
not quite enough material to completely wrap a 40 HP. Merc. - at least not
without cutting on the diagonal and piecing together, anyway. I haven't hefted my
sheet in a while, but the stuff is pretty heavy for foam - 10-12# per sheet or
so, maybe, or maybe not. (I can be as enlightening as an ad copy writer if I
try hard enough!) The 1/2" stuff goes for $70.00. I didn't order the
"installation hanger kit," but the sheet I received had a goodly bunch of bits thrown in
the box that seemed to correspond to the description given.
The product seems primarily intended for installation on the interior
surfaces of an inboard engine box. I'm pretty sure that the foam is of the open-cell
variety, which might or might cause problems used in an outboard well -
perhaps any water that got into the foam would only enhance the sound-deadening
properties, perhaps the stuff would delaminate or provide a home for obnoxious
biological growth. I dunno.
My Merc is conventionally mounted on a transom, sticking up in the air for
all the world to admire. My plan is to incorporate the foam in a fabric sack
that I can pull over the powerhead and secure with a drawstring around the bottom
of the powerhead. In appearance it would look like an oversized sleeping bag
in a stuff sack. I believe that West Marine once sold a ready-made cover like
this but their current catalog doesn't carry any, so evidently it wasn't a big
seller. Seems like a good idea to me, but time will tell. I doubt if I will
get to this project this summer.
Please let us know what, if anything, you come up with. The person comes up
with a slick way to soundproof old powerheads will be a public benefactor. If
that person came up with a commercially viable product that boatowners would be
motivated to buy and install in large numbers, he/she would deserve
canonization!
Ciao for Niao,
Bill in MN
[Non-text portions of this message have been removed]
writes:
> For example, name/source of foam - CdnWest Marine sells sheets of "noise control barrier foam" - they don't have
> sources appreciated. Thanks Cam
>
any lead in them, but have a sheet of PVC sheet sandwiched between two foam
layers. They claim it provides "dramatic noise reduction compared with single
layer foam barriers." I can't say I find this ad copy claim particularly
enlightening.
One side is faced with shiny aluminized mylar film and the other has
peel-and-stick adhesive. The foam layers are different in thickness and perhaps
composition. I infer that the shiny side is supposed to face the source of the
noise. I haven't tried it yet, so can't speak to how effective it is.
The stuff is pretty expensive. 32" by 54" by 1" goes for $90 + S&H and is
not quite enough material to completely wrap a 40 HP. Merc. - at least not
without cutting on the diagonal and piecing together, anyway. I haven't hefted my
sheet in a while, but the stuff is pretty heavy for foam - 10-12# per sheet or
so, maybe, or maybe not. (I can be as enlightening as an ad copy writer if I
try hard enough!) The 1/2" stuff goes for $70.00. I didn't order the
"installation hanger kit," but the sheet I received had a goodly bunch of bits thrown in
the box that seemed to correspond to the description given.
The product seems primarily intended for installation on the interior
surfaces of an inboard engine box. I'm pretty sure that the foam is of the open-cell
variety, which might or might cause problems used in an outboard well -
perhaps any water that got into the foam would only enhance the sound-deadening
properties, perhaps the stuff would delaminate or provide a home for obnoxious
biological growth. I dunno.
My Merc is conventionally mounted on a transom, sticking up in the air for
all the world to admire. My plan is to incorporate the foam in a fabric sack
that I can pull over the powerhead and secure with a drawstring around the bottom
of the powerhead. In appearance it would look like an oversized sleeping bag
in a stuff sack. I believe that West Marine once sold a ready-made cover like
this but their current catalog doesn't carry any, so evidently it wasn't a big
seller. Seems like a good idea to me, but time will tell. I doubt if I will
get to this project this summer.
Please let us know what, if anything, you come up with. The person comes up
with a slick way to soundproof old powerheads will be a public benefactor. If
that person came up with a commercially viable product that boatowners would be
motivated to buy and install in large numbers, he/she would deserve
canonization!
Ciao for Niao,
Bill in MN
[Non-text portions of this message have been removed]
Cam,
I have a drawing in an old book (1964) showing a box with a small hole
at the front for the tiller, covering the motor but with the rear of the box
cut away. The box is lined with glued-on foam. The idea is that the noise is
left behind.
I would urge a water cooled motor, not air cooled.
Alvan.
I have a drawing in an old book (1964) showing a box with a small hole
at the front for the tiller, covering the motor but with the rear of the box
cut away. The box is lined with glued-on foam. The idea is that the noise is
left behind.
I would urge a water cooled motor, not air cooled.
Alvan.
Cam - I have some interest in Bantam also. Where are you located and might you want to do some direct communication?- Jim
----- Original Message -----
From: Cam Alexander
To:bolger@yahoogroups.com
Sent: Monday, June 09, 2003 10:50 AM
Subject: [bolger] Help with outboard sound-proofing
I am trying to find a way to quiet a two-stroke outboard. The ideal
solution is a four-stroke, but that will have to wait a while $$ 8-(.
I'm lusting heavily after building a Bantam, and would like to get
the quietest & cheapest propulsion; there's a lot of used two-strokes
out there. I've heard of lead lining as well as foam. Anyone out
there with experience? For example, name/source of foam - Cdn
sources appreciated. Thanks Cam
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[Non-text portions of this message have been removed]
>--- "Cam Alexander" <calex@e...> wrote:Lead blankets or sheeting is often used among many other things in
>> I am trying to find a way to
>> quiet a two-stroke outboard.
buildings, but adding lead to a boat seems silly.
I'd suggest a sandwhich of ply and extruded foam (1/4" ply perhaps
and 1/2" foam and 1/4" ply on the inside) as the "shell" over the
engine, and fiberglass batting on the inside.
This is assuming the outboard is in a covered well. You can rig a
couple pipes to the outside for ventilation and perhaps come up with
an air intake setup ... don't ask me <chuckle>. Somewhere around I
have a Chapelle boat from the 1950s with an outboard well amidships
with this sort of arrangement.
--
Craig O'Donnell
Sinepuxent Ancestors & Boats
<http://freepages.genealogy.rootsweb.com/~fassitt/>
The Proa FAQ <http://boat-links.com/proafaq.html>
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Sailing Canoes, Polytarp Sails, Bamboo, Chinese Junks,
American Proas, the Bolger Boat Honor Roll,
Plywood Boats, Bamboo Rafts, &c.
_________________________________
-- Professor of Boatology -- Junkomologist
-- Macintosh kinda guy
Friend of Wanda the Wonder Cat, 1991-1997.
_________________________________
---
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--- "Cam Alexander" <calex@e...> wrote:
is that high frequency sound can
be stopped by a thin, but relatively
air tight 'shell'. Low frequency
sound is only stopped if the 'shell'
has significant mass.
I think that the accoustic baffling
applied to the walls of a music room
serve mostly to scramble the echoing
inside the room, and you still need
'air tightness' and 'mass' to stop the
sound from passing through the walls.
Of course, gas motors need to breath
air, and cannot function long in an
air tight chamber.
> I am trying to find a way toThe theory, I recall from school,
> quiet a two-stroke outboard.
is that high frequency sound can
be stopped by a thin, but relatively
air tight 'shell'. Low frequency
sound is only stopped if the 'shell'
has significant mass.
I think that the accoustic baffling
applied to the walls of a music room
serve mostly to scramble the echoing
inside the room, and you still need
'air tightness' and 'mass' to stop the
sound from passing through the walls.
Of course, gas motors need to breath
air, and cannot function long in an
air tight chamber.
I am trying to find a way to quiet a two-stroke outboard. The ideal
solution is a four-stroke, but that will have to wait a while $$ 8-(.
I'm lusting heavily after building a Bantam, and would like to get
the quietest & cheapest propulsion; there's a lot of used two-strokes
out there. I've heard of lead lining as well as foam. Anyone out
there with experience? For example, name/source of foam - Cdn
sources appreciated. Thanks Cam
solution is a four-stroke, but that will have to wait a while $$ 8-(.
I'm lusting heavily after building a Bantam, and would like to get
the quietest & cheapest propulsion; there's a lot of used two-strokes
out there. I've heard of lead lining as well as foam. Anyone out
there with experience? For example, name/source of foam - Cdn
sources appreciated. Thanks Cam