Sound deadening material for engine boards?

[Boat afloat]

I’ve used the search function but couldn’t see any discussion around sound deadening options for engine boards.

 

we have an old BMC Tempest engine and I’d like to find easily implementable (and cheap) ways of reducing noise on the stern for more comfortable cruising.

 

im going to perform an oil change, because a clean engine is a happy one but have also been considering noise reduction pads for the underside of the (wooden) engine/stern boards. Has anyone tried this sort of thing with good results or indeed tried anything else that worked?

Someone has mentioned hospital silencers but that seems like a bigger job for another day, and at considerable cost. I’d be happy with something I can install next week, on my own without having to warn the bank manager!!

 

below is the stuff I have used in automotive applications in the past.

 

cheers

 

Edited April 16, 2022 by Boat afloat

[Thames Bhaji]

You get what you pay for, and anything that thin probably won’t make much difference. The stuff I used was along the lines of the product below, and you can see a few variations on the ASAP site. It really wants to be at least an inch thick and quite heavy. 
 

https://www.asap-supplies.com/products/quietlife-32mm-soundproofing-with-lead-barrier-silver-foil-x4-801484

[Boat afloat]

3 minutes ago, Thames Bhaji said:

You get what you pay for, and anything that thin probably won’t make much difference. The stuff I used was along the lines of the product below, and you can see a few variations on the ASAP site. It really wants to be at least an inch thick and quite heavy. 
 

https://www.asap-supplies.com/products/quietlife-32mm-soundproofing-with-lead-barrier-silver-foil-x4-801484

thanks for that. Yeah that’s quite a bit more expensive than the stuff I used but if it works then it’s worth a go.

 

did you notice much difference when you used something similar and did you deem it a value for money job? 

[Quattrodave]

I used this:

 

https://www.ebay.co.uk/itm/263415099245?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=IA0irpl2QnG&sssrc=2349624&ssuid=yeWIvTWvSVy&var=&widget_ver=artemis&media=COPY

 

married with the thickest MLV (mass loaded vinyl) you can purchase.  It works really well, do the boards, sides, firewall & stern.  The only other thing to consider is vibration, are your engine mounts good...

[Murflynn]

and check if the engine mounts are transferring the engine vibration into the boat structure.  "sound deadening" of the covering boards only addresses a small part of the problem.

[pearley]

Just bought 5 of these panels to do my engine bay. Let you know when fitted how it is.

http://www.soundservice.co.uk/foam_laminates_SA25FFB6 _SA25FFL6.html

[OldGoat]

I fitted Quietlife insulation in our biuld.   Whether it makes that much difference I don't know as the deckboards reduce some of the noise.

 

If you want a quiet(er) boat you need a freshwater cooled engine... But that's too revolutionary.

[Thames Bhaji]

2 hours ago, Boat afloat said:

did you notice much difference when you used something similar and did you deem it a value for money job? 

It did make a difference, but as others have said it was one of several things that helped. You need to try to work out what each sound is being created by. I’ve recently made the biggest difference so far by a) changing my props which had previously been creating a deep drumming and b) rubber mounting my thrust bearings and electric motors that had previously sent noise throughout the hull.

[GUMPY]

30 minutes ago, OldGoat said:

I fitted Quietlife insulation in our biuld.   Whether it makes that much difference I don't know as the deckboards reduce some of the noise.

 

If you want a quiet(er) boat you need a freshwater cooled engine... But that's too revolutionary.

Almost🤭

Just a water cooled exhaust would be good enough.

Mine has that plus sound deadening 🥱

Edited April 16, 2022 by Loddon

[David Schweizer]

Diesel engines are noisy, but having started my boating on a former Working Boat, I guess that the BMC on Helvetia sounded much quieter. Nevertheless, when Helvetia's engine was re-built, I did replace the tatty old felt insulation in the engine box with Quietlife Insulation board which reduced the noise a bit.

 

 

 

 

Edited April 16, 2022 by David Schweizer

[David Mack]

How well do the deck boards fit? Any gaps will let sound through.

Others have reported improvement simply by fitting foam strips to the underside of the boards where they rest on the supporting beams. This will both reduce sound transmission through the air gap and cushion any drumming which may occur if the deck boards vibrate.

[beerbeerbeerbeerbeer]

57 minutes ago, David Mack said:

How well do the deck boards fit? Any gaps will let sound through.

Others have reported improvement simply by fitting foam strips to the underside of the boards where they rest on the supporting beams. This will both reduce sound transmission through the air gap and cushion any drumming which may occur if the deck boards vibrate.

Would weed hatch tape be sufficient? 

[Ryeland]

What made the biggest difference for me was to seal the edge of the engine cover board when it is down by a strip of butyl rubber foam.

 

Richard 

[Chris Lowe]

Rockwool acoustic insulation might help Rockwool

[Tracy D'arth]

90% of the noise comes through 5% of the gaps. You need to totally cover the deck but then you may need to think about how the engine is ventilated. Furnace Vale Marina did some great sound absorbing stuff with a lead layer in.

 

You will need to screw the stuff to the boards with big washers, don't rely on any glue holding it on against gravity when it gets hot under there.

[ditchcrawler]

Its surprising what difference a good thick rug or carpet will do laid on top of the boards

[Mike Jordan]

As already suggested it’s far more effective and cheaper to effectively seal the engine space to contain the noise.

The deck boards are ideally hinged and fitted with “budget” locks which operate with a square shaped key together with gas struts to hold them open when needed. The adhesive foam strip must be compressed when the boards are locked down to make the deck airtight. Obviously air must be admitted through a sound trapped vent to keep the engine running.

It’s not a five minute job but works much better than trying to absorb the noise. My last two boats were treated in this way together with absorbent materials on the underside of the boards. On several occasions I was asked what engine I had, only to surprise the person asking by saying it was a 1.8 Leyland rattling like all the others but sealed in. Photo to follow with luck!

[Mike Jordan]

Showing stainless steel hinges and plated budget locks

Foam rubber strip 6mm X 25mm