exhaust pipe insulation for sound ?

[Canuck Dennis]

O.K. all alternatives seem off the table as to adding additional mufflers on my 43 DC..so am considering wrapping all the pipes and existing mufflers with some sort of sound insulating blanket..any ideas ??? as to make and type etc

 

[REBrueckner]

What boat is this? What is the problem you are trying to solve....?? Can you even HEAR interior exhaust sound with engines running???

On a boat, overall sound/noise level doesn't seem to come much from interior exhausts....but from the engine low frequency sounds and resonations thru the hull....and of course the stern exhausts....

 

[Canuck Dennis]

1979 43 DC.......vernatone muffler ea side one in Master Head other in Master closet....pipe then runs within cabinetry to transom....cannot add mufflers due to space restrictions...most noise is in the steering station and comes from a combination of exit noise from the pipes plus emitting from the pipes within the boat.....any added soundproofing will surely help.

 

[Robby]

Our boat is eariler than yours and the only time its truly noisy is with the engine cover off in the salon.Robby

 

[Glory]

I added foam to the areas that my exhaust pass, It made differance of 4 db in the aft SR. I didn't secure the foam in just cut it to fit and stuffer it in. I did this mostly because there are wires, plumbing and AC lines passing in the spaces and I didn't want to restrict access.

JM

 

[George]

There is a special paint for marine use that deadens sound. You may want to do some research, but from what I recall, the results are amazing. Here is a link you may want to check out.
http://silentcoating.com/index.html

 

[Canuck Dennis]

seen that but was skeptical...maybe a bit of both would really be good...thanks for the reply.

 

[Glory]

Noxudol 311 Waterbaed sound damping compound, you can google it. I have been thinking about using this myself, I'm just not that far down the list.

JM

 

[REBrueckner]

(no "sure fire" solutions here...just some considerations.....

You sure your mufflers are working and that you are pumping adequate raw water??? (unsure exactly how to test either except by judgement.)

On my 1972 48 YF there were huge (perhaps 2ft x 2ft x 3ft) fiberglass mufflers at the aft end of the engine room, and mostly flex hose after the mufflers to the stern....With engines running at cruise all I could hear in the aft stateroom was engine noise from the engine room...which of course reverberates all over the place...hull, bulkheads, floor and so forth. I would think that's the best way to muffle exhaust noise....mufflers near the engines....Where do they place mufflers on the newest boats???

If you have a swim platform how about temporarily placing some foam of some sort or other material on the platform over the exhausts and see if that makes any difference. On my 1972 48 YF I carried an inflatible across the stern swim platform for several years and it was a BIT...not a lot... quieter than when I towed it....but NOT a big difference....but my exhaust was quiet at cruise speed anyway.


Seems like a basic decision is whether to focus your noise attenuation efforts before or after your mufflers...Your stbd muffler is forward of the stbd berth?? Unsure where your "master closet"...are you referring to the one across the stern aft of the port bunk?? Seems like sections after the muffler should be less noisey.

We've talked about side angled exhaust extensions at the stern...mainly to get exhaust smoke out of the stern area.....does this make any difference in exhaust noise????

Is the exhaust material fiberglass tube or flexible hose where you believe the majority of noise to be?? I would think flex hose is quieter than the rigid fiberglass tubing....Anybody know for sure??? Are you sure any rigid fiberglass tube in padded at the points where it is fastened....There should be some padding under the metalattachment ring but maybe you can add some there and see if it makes any difference?

Anything to reduce vibration of the exhaust should help....that's one reason why cast iron drain pipes in homes versus copper tubing or PVC is so quiet...it's so dense and heavy it barely vibrates and the material also blocks sounds.

Not be discouraging, but my limited efforts with adding soft foam or or other lightweight material suggests it is unlikely to make much difference....

 

[Canuck Dennis]

Rob, on my 43 dc the master is a centreline Queen, cabinets outboard both sides, thats where the f/g exhaust runs and it's sort of in a "tunnel" which adds to the reverb effect also, the muffler are just aft of the e/r bulkhead and hard to tell if still serviceable but appear to be sized for the engine HP, so I am looking for a lead lined "blanket" type of wrap, 5lbs sq ft would make a difference, as far as transom goes, not much I can do there....there used to be right angle rubber mufflers made for transom exhaust but discontinued.

 

[Bill Allen]

On my 43 (twin bunks) most of the noise is engine generated. Floor insulation would probally be money better spent. The old DD are a bit noisy especially when you spin them up. Althouh I love the sound when they're running hard at the price of fuel I doubt if I'll be listening to that sound anymore. At my slow (fuel efficent) cruise the noise in the salon is alright, But loud. At some point I may reinsulate the flooring and hull. But again sound travels following the shafts, controls etc. With the DD I doubt wheter you can truely make it quiet when the engines are running. I just live with it especially since most of the time I run on the aft station. I can't see how rapping your exhaust will make much of a diference for all the work. Bill

 

[Canuck Dennis]

The noise is in the aft station..the saloon is quieter than the aft station.

 

[Bill Allen]

What condition is the sound insulation on the bulkhead between the engine room and the aft stateroom? The penertarions between the bulkhead for the wires etc. are they all sealed, on mine the back of the electric panel is in the aft locker. Bill

 

[Canuck Dennis]

They look good specially the exhaust, the flange is fastened directly to the bulkhead and all wires seem well sealed..

 

[Bill Allen]

Interesting, I supose i'm just used to it. I know I'll be leaving Marathon next week and heading back to North Jersey so i'll hear the noise again and try to pay a bit more attention to where it seems to be coming from. Bill

 

[Canuck Dennis]

I know on my Vancouver boat, when I added waterlifts in the e/r the noise reduction was dramatic specially in the master aft where the pipes run through, so am assuming the f/g pipes emit a fair bit of noise as well as the transom exit.