How to soundproof the engine bay?

[Leemawillams666]

Has anyone had any experience with soundproofing engine bays?
What is the best way to do it? I gather some kind of lagging.
Cheers
Frank

[Robbo]

Use the correct sound insulation (see link below for reviews) if you have a large engine bay then building a box around the engine will be cheaper.

 

http://www.nkgroup.co.uk/file/2014/06/Marine-Soundproofing-YM-article.pdf

[Dave Payne]

I've been pondering this for my boat, problem I have is being a cruiser stern, I have a lot of boards, I can see insulating bulkhead being easy but not so much the boards?

[Tonka]

shut the side doors

[Chewbacka]

The BSS has strict requirements for the type of material that can be used, and carpet and lagging is not allowed in the engine compartment.

[Detling]

You can get fire resistant foam/sponge panels with either a dense vinyl sheet or a lead sheet inside. The lead is better but a lot heavier. There is a bs number required for the bss. These are supposed to be self adhesive but not very strong ok for bulkhead but deck fell off. I used bolcotan poly something wood glue (it's like spray foam but not as foamey ) and then a car Jack holding a piece of ply whilst the glue set. Been ok since. Due to the glue you need decent temperatures for it to stick, so not in January.

[Ally]

We used to use this, with a good adhesive we bought separately locally from an insulation company. There are 4 sheets to a box. Sold a load off when we closed at a tenner a sheet!

 

http://www.force4.co.uk/force-4-acoustic-class-o-insulation-silver-faced-box-of-4.html?utm_source=google_shopping&gclid=Cj0KEQiAnIPDBRC7t5zJs4uQu5UBEiQA7u5Neyusx-W2AQo8C0kzbNq5TVxQX-AHBLCqVLZebKsnNF4aAto28P8HAQ#.WGEfYeinzMI

Edited December 26, 2016 by Ally

[Arthur Marshall]

I used the stuff with a layer of something in the middle. As far as I can tell it makes hardly any difference to just the plain wood of the deck planks. Noise cancelling earphones work though.

[Mike Jordan]

There was a excellent article on this in the Waterways World some time ago, written by A fine young chap called Mike Jordan. Look it up in the back issues, the foam sandwich panels are not worth having compared to sound proofing the engine space for a few pounds.

[pearley]

Use the correct sound insulation (see link below for reviews) if you have a large engine bay then building a box around the engine will be cheaper.

 

http://www.nkgroup.co.uk/file/2014/06/Marine-Soundproofing-YM-article.pdf

Interesting read. We have cloth faced sound deadening fitted by the original boat builders and the foil faced stuff on the generator which was installed later. The cloth faced is much more resistant to damage by bits rubbing it from vibration or stuff pressing against it.

[ditchcrawler]

The BSS has strict requirements for the type of material that can be used, and carpet and lagging is not allowed in the engine compartment.

Which regulation does that come under?

[Jak]

Noise cancelling earphones work though.

They work well with the wife as well as the BMC

[RAB]

A question; If soundproofing the engine bay floor plates do you need to worry about increased engine bay temperature, or is it minimal due to the heat loss through the bottom and sides in contact with the water. Can't help thinking it will have an effect, but can't get a feel for how much?

[mrsmelly]

Which regulation does that come under?

 

Probably different ones in Canada

[Albion]

If you use sound insulating layered foam type material on any engine bay work you have to remember to make the sheets touch each other where there are the joints between boards that have to be lifted etc., because if there is any gap then sound waves will regenerate through any small gap. See: https://www.reference.com/science/happens-waves-travel-through-gap-d6b4bdfa4c279c57. If you make it an almost continuous sheet with minimal gapping then I have found material similar to this http://www.asap-supplies.com/us/soundproofing/soundproofing-sheets/quietlife-slimslab-801884 to be good but it isn't cheap of course.

Roger

[Dave Payne]

If you use sound insulating layered foam type material on any engine bay work you have to remember to make the sheets touch each other where there are the joints between boards that have to be lifted etc., because if there is any gap then sound waves will regenerate through any small gap. See: https://www.reference.com/science/happens-waves-travel-through-gap-d6b4bdfa4c279c57. If you make it an almost continuous sheet with minimal gapping then I have found material similar to this http://www.asap-supplies.com/us/soundproofing/soundproofing-sheets/quietlife-slimslab-801884 to be good but it isn't cheap of course.

Roger

There is the problem, with gutter channels I cant see this being possible? Edited December 26, 2016 by Dave Payne

[Horace42]

You need soft mounts for the engine and flexible pipes and cables including the exhaust to prevent engine movement and vibrations reaching the body of the boat,and a silencer for the exhaust.


You need soft mounts for the engine and flexible pipes and cables including the exhaust to prevent engine movement causing and vibrations in the boat panels they are connectd to.


But make sure the extra movement can be accommodated by the prop shaft.
Whatever insulating foam used make sure ALL gaps (that let the sound out, however small) are blocked.
Particularly the deck boards.

I did this and used 1" thick closed cell dense foam, fully covering on every surface.
with all joins in the foam covered with additional foam strips.

I cut an extra large hole for the air intake to compensate for the loss of air flow due to fitting an additional air filter over the grid of the air inlet hole.

Edited December 26, 2016 by Horace42

[Dave Payne]

You need soft mounts for the engine and flexible pipes and cables including the exhaust to prevent engine movement and vibrations reaching the body of the boat,and a silencer for the exhaust.

 

 

You need soft mounts for the engine and flexible pipes and cables including the exhaust to prevent engine movement causing and vibrations in the boat panels they are connectd to.

 

 

But make sure the extra movement can be accommodated by the prop shaft.

Whatever insulating foam used make sure ALL gaps (that let the sound out, however small) are blocked.

Particularly the deck boards.

 

I did this and used 1" thick closed cell dense foam, fully covering on every surface.

with all joins in the foam covered with additional foam strips.

 

I cut an extra large hole for the air intake to compensate for the loss of air flow due to fitting an additional air filter over the grid of the air inlet hole.

Might just be passing you the next couple of says, would be nice to ha e look if that's ok?

[blackrose]

You need soft mounts for the engine and flexible pipes and cables including the exhaust to prevent engine movement and vibrations reaching the body of the boat,and a silencer for the exhaust.

 

 

You need soft mounts for the engine and flexible pipes and cables including the exhaust to prevent engine movement causing and vibrations in the boat panels they are connectd to.

 

 

Sound which is perpetuated through vibrations via solids is significant and often overlooked - probably because it's more difficult to isolate the sources than it is to attenuate airborne sound with sheets of materials of various densities. So when people say that their soundproofing hasn't made much difference that's often one of the reasons. The other main reason soundproofing may not seem to work is because low frequency sounds generally have longer wavelengths which are more difficult to attenuate (absorb) with a couple of inches of foam than high frequency (short wavelength) sound. This is why you can hear the bass sounds coming through the neighbour's wall even though you may not be able to identify the tune - the high frequency sounds have been attenuated and aren't coming through the wall but a much greater proportion of the longer wavelength low frequency sound energy has passed through. To attenuate low frequency sound you would either need an open cell foam of an infinite thickness or a layer of high density material like lead, but the lead doesn't actually absorb and get rid of the unwanted sound energy - it generally reflects it so it just bounces off somewhere else. The multi-layer sound insulation materials comprising foams and higher density layers are designed to absorb some sound waves while reflecting/breaking up others so that they bounce back into the material and are absorbed by the foam, but most are a compromise between attenuation efficacy and thickness.

Edited December 27, 2016 by blackrose

[Horace42]

Might just be passing you the next couple of says, would be nice to ha e look if that'ok

 

That's OK, be we might be out. Can you be definite about time? - then I will PM a private message with details.

[Jrtm]

shut the side doors

I was thinking remove the engine and get a horse

The BSS has strict requirements for the type of material that can be used, and carpet and lagging is not allowed in the engine compartment.

This mean i need to take up my carpet in my engine room? I didint notice anything for bss on it but i could have missed it

[Chewbacka]

I was thinking remove the engine and get a horse

 

This mean i need to take up my carpet in my engine room? I didint notice anything for bss on it but i could have missed it

Just had a look at the current version of the private boat check list and there is nothing I can find for engine space sound insulation. Maybe I remembered wrong, or maybe it was a new build CE requirement.

[Jrtm]

Just had a look at the current version of the private boat check list and there is nothing I can find for engine space sound insulation. Maybe I remembered wrong, or maybe it was a new build CE requirement.

Woo get to keep my nice grubby white carpet. (Not sure why or how i ended up putting a cream/white carpet down in the engine room prob not my best move)

[cuthound]

Woo get to keep my nice grubby white carpet. (Not sure why or how i ended up putting a cream/white carpet down in the engine room prob not my best move)

Well, looking on the bright side, it makes spotting oil leaks easier

[NB Lola]

I added a hospital silencer plus fire resistant soundproofing material on the underside of the deck boards (cruiser stern) and behind the step down into the boat. We have had a few comments on how quiet it is.