Sound Proofing?

[Greg S]

I'm looking to replace the sound insulation in the engine compartment. Has anybody installed some sound proofing lately that you've been happy with? Or maybe you're not happy with what you used and might want to share some thoughts? Would appreciate any input.

Thx, - G

[Weyalan]

I recently built a new engine box using marine ply and hardwood cleats/framing. I lined the inside with sound insulation... the foam type which has silver foil fire retardant on one side and a layer of lead (or, more accurately, some other rubber-like compound that seems to weigh almost as much as lead). I found the stuff easy to work with (sharp scissors or stanly will cut it fine, with care), easy to affix (contact adhesive), I bought a roll of 2" tape of a similar material to the fire retardant, for the seams, and am happy with the results. My only complaint is the weight, but, apparently, this is standard material, plus the weight is fairly low down.

[Alan Wheeler]

There are a few on the market now. But I used to sell and have used a product called Acustop. Was very good. It was damn expensive though. It used a barium oxide layer inbetween foam sandwiches to mechanicaly isolate the sound energy. There are versions with lead in them and then there are the new materials that are just a white plain fluffy substance.
For an engine room you need to ensure two things. The insulation needs to have a silver finish to one side of it. This keeps the oil out which will break down the foam very quickly, and it keeps the heat out which will break down the glue very quickly.
Think of sound as pressure. Sound will want to "squeeze" through holes. so you insulation job is only as good as the covering. The more you cover, the better your absorbtion will be.

[skipperaris]

I did this two years ago and am very happy with the result.
The motor sounds a lot quiter than it did.
I used a locally made material and fixed it in place with contact adhesive.
The overall thickness is 30 mm and the cost was € 58 / sq.m.
I used 3.5 sq.m.

Anything else you want to know?

[cat man do]

I was thinking about using this product QUASH available at a few places but on the web here Consolidated Metro Group

Go to pricelist and look for Quash

The rep I spoke to say's while not as good as the stuff with the Barium, it was a lot better than the straight accoustic foam, and a whole lot cheaper and of course weigh's almost nothing.

I have a small sample here and it cant be lit with a lighter, but does melt.

Like the model T, it comes in white and black.

Any thought's?

Dave

[Alan Wheeler]

Hi Dave, From what I can make out in the picture, is that stuff a plastic- large closed cell foam type stuff?? I think I have seen it in freight protection lining boxes so goods are not damaged.
Hmmm, not sure how it would handle low freq sound from an engine, but I am certainly interested in how it works out, so keep us posted. I also couldn't see how some of the new sound materials work. A white hollowfill type fibre. Yet they seem to work, so I won't knock your one till I hear how it works.....or not.

[GordMay]

Dow’s “Quash” acoustic foam is the constituent product, urtilised by foam fabricators (manufacturers) in producing an end-product.
Dow “Quash” Sound Management (acoustic) Foam is a low-density closed-cell, non cross-linked, extruded polyethylene foam; which makes it inherently resistant to water absorption. Quash is particularly efficacious toward absorbing the lower frequency noise energies.

[Jon D]

We reinsulated our engine room a year or so ago. Used a combination of Glacier Bay's prduct which is 1 1/2" thick and the sailors solution squares where thickness was an issue. Was an improvement over the old stuff that was there.

[Greg S]

Thanks for all the input! I currently have the foil backed foam and the foam is falling out the bottom. Of course it's lasted 16 years, so maybe that's the way to go again. Also, maybe it's better made now.

Dave, The QUASH sounds interesting. Did the mfg indicate any special requirements for attaching it? Glue it on I suppose?

I was also wondering about a product called Silent Running 1000. Practical Sailor did a rather limp review of it, basically saying that after painting it on a piece of sheet metal and wacking it with a hammer it wend boink, insted of bonk. I'm not at all convinced it's suitable for an engine compartment. It's a paint on product and but pretty pricey stuff, so I guess I'd rather have a better review of it. Has anybody used, or heard of this stuff?

[skipperaris]

Just a thought Greg.

I changed my insulation when I took out the motor for an overhaul. Even then I had to work doubled up in the engine compartment.

Have you thought how you'll have access to where the old insulation must come away and the new go in with glue on both the supporting surface and the new sheet of insulation?

As for Silent Running 1000 it sounds like the tarry coating on car body panels to deaden the sound of the sheet metal panels flexing as you drive along. It also serves as a rust inhibitor.

Of course I could be wrong.

[knottybuoyz]

I'm not positive but I think Silent Running 1000 is what's used in the 47' MLB's build in Canada.

SR 1000 Silent Running - World's Best soundproofing and vibration dampening Products

Could also be this one....

Delta T Marine Ceramic Insulating Paint and Coating

[cat man do]

Hi Greg S, i'd be guessing about the glueing of Quash, maybe some sort of contact glue would be used?

I asked about sillent running on a post on CF a while back, and spoke to the suppliers in OZ about it and got shown the same bang the bit of metal test with a huge difference displayed.

While I agreed that this would shut up some of the engine contact through structure noise, I wasn't convinced on the air born noise being absorbed by the product.

While promising to put me in contact with user's who have had great result's, six mth's later and at least a dozen phone call's have produced no result's on speaking to said user's.

It is a shame as if it is as good as they say, it would be the best thing to use, for me at least.

Dave

[Greg S]

skipperaris - Fortunately I have pretty good access to the engine compartment. Even at that I know it's going to be an ugly job to get all the old insulation removed and the surfaces, FRP and wood, clean enough to apply any new insulation.

Rick - The Delta T Marine stuff, Delta~db, sounds very similar Silent Running product. Both seem to work by turning sound into low-grade heat. Applications, drying times, etc are also close to the same. Booth would seem to be possibilities.

Dave - The Quash product looks to be a little too thick for the space I have. The Silent Running stuff would seem to be a nice way to go. I like the claims and the application of it, but you're right, it's tough to spend that amount of time and $$ on something with so little real world results to go on.

Thanks again everybody for the input. No matter what I decided to use, I'll have to wait 'till the weather warms up a bit first so I can keep the boat open for the gluing or painting. Plenty of time for procrastination!

Greg

[cat man do]

A bit more info on Quash for all you tech head's.

How does it stack up compared to some of the other stuff ?

Dave

[skipperaris]

Originally Posted by Greg S

skipperaris - Fortunately I have pretty good access to the engine compartment. Even at that I know it's going to be an ugly job to get all the old insulation removed and the surfaces, FRP and wood, clean enough to apply any new insulation.

Greg

You are lucky to have such a roomy engine compartment, Greg. I would not consider replacing my insulation with the engine in place. I would at least loosen it on its supports so that I could move it around enough to gain a bit more room while glueing a new sheet in. Even then it could get messy where pipes and wiring are supported to the walls over the insulation. There are also some spots with zero clearance.

If I were building my yacht from scratch I would put the motor in the middle of the salon with removable insulated walls all around it