sound deadening

[dreadnought]

hi all,can anyone give me any tips on sound proofing my engine bay,what does the forum recommend product wise, many thanks

[koukouvagia]

Hmm.  Trying to post a reference to a previous thread that deals with this.  All I seem to be able to get is an irrelevant posting within the thread.  

I give up.

Google "Canalworld sound proofing"  There's plenty of information on this site dealing with this subject.

 

 

 

 

Edited July 22, 2017 by koukouvagia

[Robbo]

21 minutes ago, dreadnought said:

hi all,can anyone give me any tips on sound proofing my engine bay,what does the forum recommend product wise, many thanks

Here’s a article on sound insulation; https://www.nkgroup.co.uk/wp-content/uploads/2014/06/Marine-Soundproofing-YM-article.pdf

Here’s a previous topic on the subject.

The main thing is that noise comes from exhaust, engine and drivetrain.   Each one needs to be tackled differently.

Edited July 22, 2017 by Robbo

[chubby]

only this morning i read a thread from 2013 which was good w links to products . 

It was titled " how to make an engine bay quieter - boat building and maintenence " 

 

[DHutch]

Big silencer for the exhaust, but for preventing it coming through the deck boards you need both something with mass to block transmission, and something to absorb what's retained, ideal with some mixed layers. Glass matting, and lead sheet. 

You also need to ensure you maintain reasonable clearance and ventilation to hot parts, do not rely on anything sticky back above the engine or near the exhaust.

Also look at the engine mounts!

 

Daniel

[Neil2]

Most engines are flexible mounted but they still transmit vibration - noise - through the hull via the transmission.  Fitting an Aquadrive or Python drive makes a big difference by allowing the flexible mounts to do their job properly. 

A big/hospital silencer is probably the best value for money thing you can fit though.  

[Tony Brooks]

Also exhaust through the back, not the side so sound does not bounce back from the bank.

My engine is surrounded by a fairly easily dismantled plywood box with sound deadening stuck on the inside. It uses less expensive materiel than trying to cover the whole engine bay in sound deadening.

[Murflynn]

1 hour ago, Neil2 said:

 

A big/hospital silencer is probably the best value for money thing you can fit though.  

it is certainly a good investment for reducing the sound heard by passers-by, but I didn't notice much improvement from the tiller position because the major part of the noise was not associated with the exhaust .

when I ran my Isuzu 55 engine at tickover whilst on the hard I had to put my ear next to the exhaust outlet to hear it at all.

Edited July 22, 2017 by Murflynn

[Detling]

After I had put loads of lead filled foam onto the underside of the deck boards I will got a reduction in noise level, when I did the rear bulkhead I got as much sound reduction again. I have not yet found a way of stopping everything rattling to the small vibrations that escape through the engine mounts but am working on it, cupboard doors, glasses on the shelf, even the keys on the hook, all are audible now, and so is the wife.

[Neil2]

40 minutes ago, Detling said:

After I had put loads of lead filled foam onto the underside of the deck boards I will got a reduction in noise level, when I did the rear bulkhead I got as much sound reduction again. I have not yet found a way of stopping everything rattling to the small vibrations that escape through the engine mounts but am working on it, cupboard doors, glasses on the shelf, even the keys on the hook, all are audible now, and so is the wife.

That's what the Aquadrive does.  Flexible engine mounts should not transmit vibration, most of it goes through the transmission.  No rattling glasses/doors etc on our boat.

[Chewbacka]

3 hours ago, Detling said:

After I had put loads of lead filled foam onto the underside of the deck boards I will got a reduction in noise level, when I did the rear bulkhead I got as much sound reduction again. I have not yet found a way of stopping everything rattling to the small vibrations that escape through the engine mounts but am working on it, cupboard doors, glasses on the shelf, even the keys on the hook, all are audible now, and so is the wife.

A quiet engine does come with certain disadvantages, so you may want to think about how quiet you really want your boat..................

Silencing all sources of unwanted noises is not always possible.

[Tom766]

I'm in the middle of sound deadening my engine bay, the whole deck is chequer plate so its a huge sound box down there. I bought 10mm thick rubber sheet with heat shielding foil.  Unfortunately there are a couple of big gaps around the steps into the boat which were left when the deck was made. Closing the gaps will make a vast improvement I hope...

Wondering what a silencer would cost to have made/fitted, the pipe is straight through!!

[ditchcrawler]

6 minutes ago, Tom766 said:

I'm in the middle of sound deadening my engine bay, the whole deck is chequer plate so its a huge sound box down there. I bought 10mm thick rubber sheet with heat shielding foil.  Unfortunately there are a couple of big gaps around the steps into the boat which were left when the deck was made. Closing the gaps will make a vast improvement I hope...

Wondering what a silencer would cost to have made/fitted, the pipe is straight through!!

I just fitted one of these about £80 https://www.asap-supplies.com/exhaust/dry-exhaust-silencers-accessories/exhaust-silencers/dry-exhaust-noise-silencer-sn112-417008

[Northstar]

there's a lot of good acoustic info and products in the construction sector in which i work, but the main principal is to prevent the noise transferring onto surfaces which link to the areas you wish to silence using a mixture of dense and aerated materials that break down the frequency pattern of the noise.

if i knew more about the specific problem i would be able to suggest a fix.

[Northstar]

My solution to my engine bay lid was quite simple and very effective, I used an 18mm all weather deck board often used on wagon decks which after 12 years still looks good. I stapled a sheet of 10mm dense closed cell foam (throwaway packaging) to the underside of it right up to the edges which is important because the board sits on the rain gulley edge and by making the foam seperate the board from the steel support it isolates the floor from transmitting sound from the engine bay and the hull generally.

I had considered using checker plate aluminium but metal is an efficient conductor of sound whereas timber is a natural insulator. I also would have had to apply a slip resistant coating.

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[JJPHG]

On 22/07/2017 at 22:32, koukouvagia said:

Google "Canalworld sound proofing"  There's plenty of information on this site dealing with this subject.

 

 

 

 

Apart from using the search function on the forum itself if you want to restrict your Google hits to the site itself type in "sound proofing" site:canalworld.net or "soundproofing" site:canalworld.net

[JJPHG]

On 23/07/2017 at 00:35, Neil2 said:

Most engines are flexible mounted but they still transmit vibration - noise - through the hull via the transmission.  Fitting an Aquadrive or Python drive makes a big difference by allowing the flexible mounts to do their job properly. 

A big/hospital silencer is probably the best value for money thing you can fit though.  

Not come across these before - anybody know what they are like reliability/cost wise?  Do they really reduce noise/vibration by 50% as claimed?

[Neil2]

5 minutes ago, JJPHG said:

Not come across these before - anybody know what they are like reliability/cost wise?  Do they really reduce noise/vibration by 50% as claimed?

The Aquadrive in my boat is now 30 years old still on the original bearings, they are extremely durable.  Ballpark figure for a complete installation I guess £1500, Python drives are cheaper and according to one hire fleet operator, less durable.  I don't know about a figure of 50% or what criteria they use for coming up with that figure but I wouldn't have a narrowboat without one.  They can't be fitted to all narrowboats mind, often there isn't enough space behind the gearbox output flange. 

[theodon]

I agree that Aquadrive is heavy-duty. It is worth the cost.

[Machpoint005]

On 8/15/2017 at 22:00, Neil2 said:

I don't know about a figure of 50% or what criteria they use for coming up with that figure

That's why they use it -- you would get a different answer subjectively than you would mathematically, because the human hearing response to a change in levels is non-linear.  The answer could be anything between 3dB (only just discernible) and 10dB (definite improvement).

[Kwacker]

http://www.soundservice.co.uk/marine_noise_reduction.html