Soundproofing, worth the cost?

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SimonA

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I've been looking at boxing in my engine with sound proofing panels, I've an ancient BMC diesel which sits under the helm position. The panels I'm looking at are the Quietlife 2 45mm at £85 for two sheets and the Quietlife standard at £111 for four sheets. The more expensive sheets claim a noise reduction of 29db and the cheaper ones 24db, both seem a very small reduction.

Has anyone used these products and is the noise reduction worthwhile?
 
Unable to comment on those specific products but I have added sound proofing to an engine box in the past and it did make a noticeable difference. Do you know how many db you have at the helm while cruising without the sound proofing?
 
I don't have anything to measure how many db I currently have, all I know is it it loud enough to make a conversation difficult and at present I don't have any sound proofing so the large engine bay amplifies the noise.
 
the products seem to be good, I have no experience with these, but I do have experience with acoustics.
the panels have one or more heavy layers inside and that is good for sound proofing
if you do the work of placing such panels, I would go for the thickest size, and most heavy weight / m2 you can get
mass stops the noise, not so much foam.

24..29db reduction is a lot, it would surprise me if you can achieve this with these panels,
also there will be area's where you cant place the isolating panels such as vent openings, .....

but placing the panels will anyway be a improvement regarding noise.
I guess something like 10db. (or less depending on many variables)

as a test use a db meter app on your smarphone, (doesn't need to be calibrated)
play some load music at a level compareable with your engine noise
reduce the music level so that the reading drops 10db,
this give a idea of a potential noise reduction,
10dB appears like the noise has been halved
 
Sound proofing is difficult to determine how effective it will be.. You have the airborne sound and the vibration sound that is being transmitted through the hull..

For airborne sound the soundproofing materials you speak of will reduce the radiated sound but to reach the quoted levels of sound reduction the system would have to be completely airtight which obviously it can't be as airflow is needed from somewhere for the engine.. You can create baffles (http://www.soundservice.co.uk/images/box.jpg ) with sound reducing material so there is no direct path for the sound to follow without hitting sound absorbing material but that means you need some space to create it or have some form of double skin to the enclosure.. Obviously material lining the engine bay will help but just how much is hard to determine..

For the noise transmitted through the hull you would need to look at the engine mounts and how much vibration they can absorb.. Perhaps there are larger/softer ones that would help..
 
Suggest that you give Paul Collins at Classic Acoustics a call on 01952 587360.
He is very clued-up and can supply whatever you need.
I've used 2 layers of dense polymer foam each ~15mm thick with an interlining of polymer lead.
he can apply self adhesive to the inside face for easy application and i'd recommend an aluminium layer facing out for easy cleaning and to reflect light into the engine bay.
All 'O' rated for fire resistance
Probably at less cost than elsewhere.
Have fitted to 2 boats now with a noticeable reduction in noise level.
 
I know 29db noise reduction doesn't sound a lot but it really is.

The decibel scale is logarithmic, so every 3 dB reduction is effectively halving the noise level in real terms. 29dB is a big reduction.
BUT as has been said above, it's the GAPS you need to watch, where the noise will still get through. Cracks, joints, openings etc.
 
Sandyman said:
Soundproofing, worth the cost?

Yes without doubt.
Click to expand...

+1

I fitted a load of Noisekiller "lead sandwich" to Ariam's engine bay two years ago to replace some very tatty lightweight foam. The engine is close to the box in places which ruled out thick blocks of insulation, so I bought this thinner type and doubled it up on surfaces that faced directly into the cabin.

The difference is dramatic, you can hold a conversation between helm and galley whereas previously you had to shout down the hatch to get the person in the galley to stick their head out and listen.

The sheet has an adhesive back, but I wouldn't trust it long-term. I treated it as an aid to installation, and then used stainless screws and penny-washers to fix the material permanently. I used 4" foil tape to neatly finish joins and edges - you'll use more than you expect, so order the big roll. As others have mentioned, it's important to seal gaps and joints to keep the airborne noise in; for opening hatches I used foam strip to make a seal when closed.

The foil facing makes the engine bay look much neater and cleaner, as well as quieter.

Pete
 
If you decide home brew is the way to go be damned sure the side facing the engine cannot absorb oil. You may well have flame retardant material to start with, but soak it in oil and its a whole different story.
 
+1 to prv's comments regarding retaining in place with screws and 'penny' washers and also finishing the cut edges with foil tape - available from toolstation. Ensures clean edges so no oil can soak in.
 
Before spending a lot on the sound proofing panels get some hatch seal tape and seal round all the moveable floor panels. This will make a huge difference at very little cost. Then start on the sound proofing panels after that.
 
Thanks everyone. The first change I need to make is the engine bay ventilation which at present consists of vents into the cockpit, I'll look at changing these to outside the boat instead as a lot of noise comes through them.
 
My boat is in Spain so I don't really want to spend lots of holiday time in the engine bay fitting out. How effective would it be to just buy a few large sheets and fit them where convenient without spending lots of time cutting and joining. Lets say I can cover 75% of the surface what would be the overall loss of effectiveness by leaving 25% gaps?
 
A complete waste of money as the sound will simply bypass the sound proofing like water round a rock. With sound-proofing it's all or nothing. Apart from the hatch seal tape which will make a huge difference!
 
Thanks PCUK
That saves me money and a big disappointment until I get around to doing the job "properly". I've always thought (wrongly) that the sheets would "soak" up sound and maybe the sound hiting the gaps would get reflected around and end up getting soaked up
 
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