Engine Bay Soundproofing

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tarik

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Evening all,

I would like to reduce the engine noise in the wheelhouse, only because I have difficulty hearing harbour control etc on the radio.

Any economical suggestions?

As always many thanks for all replies.



David
 
tarik said:
Evening all,

I would like to reduce the engine noise in the wheelhouse, only because I have difficulty hearing harbour control etc on the radio.

Any economical suggestions?

As always many thanks for all replies.

David
Click to expand...

The good stuff ain't cheap and the cheap stuff ain't any good!

I used Noisekiller's lead sandwich to good effect.
Also try ASAP Supplies.
 
One thing I found helpful was to rubber mount the engine cover.
I glued fairly stiff neoprene 'hatch tape' on the edges of the box where it contacts the hull.

Then make sure things like the throttle cables, exhaust, fuel hose etc are rubber mounted where they leave the engine, and where they first mount to the hull, and don't restrict the engine on its rubber mounts.

Make sure any panels are not drumming, if so, stiffen them with battens glued on with sikaflex.

Some heavy carpet over the outside of the box is cheap to try.
 
First step is to seal all openings with thick and soft hatch seal tape. As you do more and more you will find the sound escaping to be easier to track down. You can make your own soundproofing using perforated hardboard and 40mm x 40mm timbers for the frames. Frame every surface you want to soundproof. Hull sides, bulkheads, underside of hatches etc. Then thickly paint the bottom of the framed area with the thickest creosote type jollop you can find. This acts as the sound deadening medium. Then stuff the framed area with rockwool and screw the perforated hardboard over it to keep it in place. (Paint the hardboard well before fitting). It is surprisingly effective and cheap but time consuming to make. Did it on my first boat but would now save up and buy the real stuff for convenience sake!
 
The two things that made the biggest difference on our boat were:

1. Installing a Halyard Marine Aquadrive. It completely isolates the engine from the drive shaft in vibration terms. Its amazing how much sound was transmitted through the hull etc via the shaft.

2. Lots of decent engine sound insulation. The stuff that comes in several layers with a solid heavy layer in the middle. Its heavy and not cheap, but boy does it work!

Eliminating holes and gaps helps as well. I had to leave some to allow the engine to breathe!

People comment on how quiet our engine is on Serendipity. It really is barely audible when you start it up.
 
The problem with sealing all openings is that you can starve the engine of air, which will mean having to use a blower.
The way I deadened the noise coming from my previous boat's engine, which had the T90 in a space open to the cockpit under-sole, was to use an acoustic blanket.
Most of the noise was top end valve clatter and the blanket was moulded around the rocker box.
The blanket is made of a lead sheet sandwiched between acoustic thinsulate layers in a heat resistant outer envelope. By memory I paid about £80 about five years ago.
 
PCUK said:
First step is to seal all openings with thick and soft hatch seal tape. As you do more and more you will find the sound escaping to be easier to track down. You can make your own soundproofing using perforated hardboard and 40mm x 40mm timbers for the frames. Frame every surface you want to soundproof. Hull sides, bulkheads, underside of hatches etc. Then thickly paint the bottom of the framed area with the thickest creosote type jollop you can find. This acts as the sound deadening medium. Then stuff the framed area with rockwool and screw the perforated hardboard over it to keep it in place. (Paint the hardboard well before fitting). It is surprisingly effective and cheap but time consuming to make. Did it on my first boat but would now save up and buy the real stuff for convenience sake!
Click to expand...

You should take care that nothing is going to melt and drip on the exhaust etc.
With the insulation, the box will get hotter!
'Tarry Black ****' is often used to deaden panels in cars.
The key is a heavy, flexible substance, which absorbs energy as it flexes.

Mind how you go, and think about an auto fire extinguisher for the engine box.
If nothing else it fills a bit of echoing space!
 
Elessar of this parish does the drape on sound deadening cloth. His website gives some info. Seems like a nice easy way to achieve a significant reduction in noise, without the problems that can occur trying to box the engine room in completely.
 
Gordonmc said:
The problem with sealing all openings is that you can starve the engine of air, which will mean having to use a blower.
The way I deadened the noise coming from my previous boat's engine, which had the T90 in a space open to the cockpit under-sole, was to use an acoustic blanket.
Most of the noise was top end valve clatter and the blanket was moulded around the rocker box.
The blanket is made of a lead sheet sandwiched between acoustic thinsulate layers in a heat resistant outer envelope. By memory I paid about £80 about five years ago.
Click to expand...

I have often wondered if the acoustic blankets are any good. Do they not make the engine hot?
 
A decent installation will have ducted air to the engine compartment and not rely on leaks to get the air in. Sound insulated ducting is equally easy and cheap to make and with baffles on the inboard ends stop the maximum amount of noise. Of course the trouble with yachts is that the builders don't bother to sound insulate which is why yacht engines are almost always far noisier than properly insulated motor boats.:cool:
 
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