Acoustiblok for engine compartment

[hapibeli]

I'm thinking of removing the eggshell foam in our engine compartment and replacing it with something with stronger sound deadening properties. The foam is at least 10 years old.
Does anyone have experience with Acoustiblok ? <http://www.acoustiblok.com/>
Seems pretty incredible as a soundproofing material, but as always, caveat emptor?

[exMaggieDrum]

I just looked at the website and it does not quote prices or have an order form, etc. so it looks like it is not really for small project purchase, or at least, not readily apparent. Is there a way to purchase it elsewhere?

It does look promising.

[hapibeli]

I left an email message with the company asking if they had retail sales here on Vancouver Island. We shall see what they say.

[Rock-Head]

Subscribed. My old Yanmar yammers very loudly & I would be very happy to minimize it.

[MarkSF]

I used Soundown on my engine, and it worked quite well, such that most of the noise is now from the prop and the exhaust. It is designed on sound (no pun intended) principles, with a dense layer separated by two less dense ones.

Got mine from Jamestown Distributors.

[exMaggieDrum]

I also left a message for Acoustiblock on their website asking how to purchase their products. I will post their response when I get it.

[Roy M]

I notice that they require complete encapsulation (i.e., air tight) for the product to reach full potential. In one of their videos, a high school construction site, they simply surrounded the site with the product and achieved a 10 decibel noise reduction. This is still quite significant. My engine room (and all others, as well) needs fresh air and a ventilation exhaust port to outside the boat, and the product requires a three (or so) inch air space. In a small boat, that is a large lost volume. It will be interesting to see how this product serves my particular needs. Perhaps it's all about learning how to use it effectively. Sounds (no pun intended) interesting.

[rostan1]

That doesn't mean you have to seal the area. Air can enter the compartment via an opening that is not a straight path. Put a 90 degree turn in the air path and put acoustic insulation in that path. That will attenuate the sound just about the same as if you had sealed the area.

[Moontide]

From one ofthe magazine articles on Acousticblok's web site.

Acoustiblok comes in 4’6”-wide rolls, 30 feet and 60 feet in length. It costs about $2.50 per square foot (psf). The standard material, which we used, is 16-ounce Acoustiblok, which weighs one pound psf. Two-pound-psf Acoustiblok is also available. In addition to being heavier, it is thicker and not as easy to work with, but it’s said to be almost twice as effective and costs only a bit more.


Bill

[Lepke]

If you're really looking for quiet. put down lead sheeting first.

[Bill Seal]

Look into something automotive like Dynamat. Good for underhood temperatures.

[ski69sail]

Hi there,. I have been to their head office and had a good chat about the product. I used the stuff between the floor of two noisy flats.. The product is fantastic. I intend to use it on my yacht engine room now that I have the time to carry out the work... Ray

[Roy M]

ski69sail, I am unclear about the installation. Can one use a single layer of the product, or does it require two layers with a separated air space between layers? For me, that results in a serious reduction of interior volume of my engine room and would be a deal-breaker.

[exMaggieDrum]

I just received a reply from a Mr. Paul Getts at Acoustiblok. He said that they could provide 4'x5' sheets at $65/sheet. He did not indicate what weight of sheet that was.

I asked for some info such as what weight should be used, what the suitability would be in an engine room (oil, diesel, heat), what the flammability characteristics (rating, fumes, etc.), and whether it can be installed flat to panels without furring strips. I also told him about CF.

It is very clear that air tightness seems very important as they emphasize tightly sealing all electrical boxes in walls and having slack in the spanning material between wall studs to allow the material to "move" to attenuate the sound. So it is not clear how effective it might be on older boat with no way to completely seal off the engine room. Not all gear currently mounted to the bulkheads would be able to be removed and reinstalled in my case. Possible may be but just not realistic really.

I won't be ready to do anything until after our boating season here but it sounds promising. I suspect the air space issues may be a deal killer though.

[leftbrainstuff]

Originally Posted by Roy M

I notice that they require complete encapsulation (i.e., air tight) for the product to reach full potential. In one of their videos, a high school construction site, they simply surrounded the site with the product and achieved a 10 decibel noise reduction. This is still quite significant. My engine room (and all others, as well) needs fresh air and a ventilation exhaust port to outside the boat, and the product requires a three (or so) inch air space. In a small boat, that is a large lost volume. It will be interesting to see how this product serves my particular needs. Perhaps it's all about learning how to use it effectively. Sounds (no pun intended) interesting.

Noise will be a combination of structure borne and airborne noise. Structure borne noise is dominant in a boat engine room. There is little induction roar or air movement in the engine bay. The air volume is also small. The exhaust is also cold so there is little exhaust noise to worry about.

These forms of insulation deal with the airborne component only. They will be optimised for a particular sound frequency range. You can mix and match to tune out certain parts of the spectrum.

If you map the noise spectrum its possible to achieve sound reduction close to what you predict. Unfortunately a simple dBa sound meter is pretty useless.

In our Liberty 458 with a Perkins 4-236 we have the original hard constrained layer sound deadening. It works fine for airborne noise control.

I've been addressing structure borne noise. Rattling aft stateroom door which is located close to the generator frame is the main culprit as it resonates when the generator is running. The frame is rigid and transfers structure borne energy to the door. A compression seal for this door eliminates all that noise. Simple fix.

The two ways to tune out structure borne noise are to change the stiffness or mass of the reactive component to change its natural frequency. We cant change the rotational speed of the generator so we cant change the source.

Any misalignment in your drivetrain will drive structure borne noise. Check this carefully. Alternators running too fast will also be noisy.

Any prop imbalance or shaft bend will also drive noise into the hull. This will create lots of airborne noise over a wide area.

Also look for oil canning of any flat areas adjacent to the engine room. Constrained layer sound deadening can be used to change the natural frequency and tune this out.

We can hear our electric fuel pumps which are rigidly mounted. We like this sound as you are always aware when the pump is running.



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