Insulation (or is it soundproofing?) recommendation

[djousset]

I see no recent threads on diesel engine room insulation and am curious if anyone has found "the" product. I am in the process of cleaning house in that area and tore out the old disintegrating insulation. There are products with lead, heat barriers, firewall, foam etc. I assume this is mostly about sound and not heat containment but feel free to educate me.

[tkeithlu]

You're right. While sound and heat insulation have some properties in common, I think you are talking about sound insulation. This insulation needs a vibration barrier, with lead, which is very largely plastic and only a tiny bit elastic (it makes lousy springs) being the most common effective choice. It's expensive. Effective sound reduction requires that you insulate ALL the ways that vibrations can get out of the engine compartment, with no gaps. That includes downward to your resonating hull. Ever heard what a cotter key dropped from the top of the mast sounds like when it hits the deck?

Good luck with your project.

[marcjsmith]

i used soundown 1.5" on my recent project.


it had been a whole season since I ran the engine so it was difficult to tell if it was any quieter. I think a lot less heat comes out of the engine bay though.


not quite done yet...


sorry about the two rotated images... don't hurt your neck.

[capt jgw]

Sounddown is the stuff. I don't think it's lead anymore, but a real dense plastic layer between the foam layers. Silver mylar surface is easy to clean and reflects heat. Pricey but very effective.

[tkeithlu]

That's really pretty work, Marcjsmith.

[sailcrazy]

Following. We have a foam and alum foil-like outer surface sound barrier in our eng room, but it's been installed since before we bought (in 1998) and is old. There are several tears/cuts in the material, and I have to wonder if it needs to be replaced.

[Rumrace]

Sound insulation has come a long way but that stuff is overkill for HAV. Regular sound insulation could not handle the heat of Engine room. The suspended sheet cancels vibrations and does the majority of the work. The version used in lighting gets dangerous to handle with age. Little specs of floating fibreglass bag it.

[mlydon]

I’ve used this stuff before…..

https://www.sailorssolutions.com/?pa...ils&Item=SPM01

Matt

[PaulBck]

If you if you line out a room with carpet on the floor walls and ceiling it would be very quiet, sound absorbed. If you lined the same room with aluminium sheet it would be very echo'y (is that a word?).
Aluminium is a very loud material so i'm not sure aluminium foil surfaced foam would absorb sound.
I have egg carton foam in my engine box.

[GordMay]

Originally Posted by tkeithlu

... I think you are talking about sound insulation. This insulation needs a vibration barrier, with lead*, which is very largely plastic* and only a tiny bit elastic (it makes lousy springs) being the most common effective choice...

* "Mass Loaded Vinyl"?

Diesel engines generally emit higher sound pressures, in the lower to mid frequencies, typically 125Hz to 2,000Hz.
In addition, there is low frequency structure vibration related noise.

The ratings for classifying and comparing the various sound-proofing (attenuation) materials are:

• NRC, the noise reduction coefficient, which is for absorbers. The NRC rating is between 0 and 1 and its an average of how absorptive a material can be at these four frequencies - 250, 500, 1000 and 2000.
NRC measures how well materials stop sound from reflecting, as a percentage of sound that a surface absorbs.
• STC, the sound transmission class, which is for blockers. STC is a measure of how well a material blocks sound. The higher the rating the better.

You can improve the STC of a wall by building it from a more dense material (sound insulation improves by about 5 decibels for every doubling of mass), by adding an air gap, or by adding sound absorbing material.
• In countries outside the North America, SRI (Sound Reduction Index), describing an improvement of so many decibels (dB) sound reduction, is a more common measurement.

[Scubaseas]

I put 2" Soundown in my 323 Pearson years back when they used lead sheeting as the decoupler. The product and installation manuals on the Soundown website do a good job of explaining things.

If you run a freezer or fridge and do not have shore power then getting the heat out of the engine compartment is a good thing. Sound proofing will also act as good insulation but running an engine compartment exhaust fan during and after running the engine will really make a big difference in reducing the amp hour draw. This assumes that you motor some which in the Summer in the Northeast is inevitable most mornings.

Sound proofing while expensive is dual purpose in that it reduces the noise from the engine and also keeps the heat out of the fridge and the salon. It's harder to put in than plain insulation as it needs screws or mechanical attachment but worth the effort IMHO. A good time to do the job right is if you ever have the motor out and can easily access the compartment.

If you don't cruise with a fridge and the motor noise doesn't bother you, you need not do anything. If the cabin getting hot or you use the fridge and motor a lot then insulation alone works, especially if you run a blower when motoring to exhaust the heat of the engine. If you want it quieter and insulated go with Soundown or similar product.

[Rumrace]

My Son in Law is a rock n roll star. They are just leaving on a European tour. The guys have a studio which is mind boggling
I met their sound architect. He explained a few things to me which I barely comprehend. The aluminum is glued to the cellulose or fibreglass the sound vibration hits the metal and is disrupted and transmits through the thin fibres dissipating
Their air intake and exhaust are 3 meters in diameter filled with black foam and the whole room floats on massive springs. The recording room is built the same way and floats separately connected by a floating passage with freezer doors at each end.
So it stopping vibrations kinda

[marcjsmith]

Originally Posted by sailcrazy

Following. We have a foam and alum foil-like outer surface sound barrier in our eng room, but it's been installed since before we bought (in 1998) and is old. There are several tears/cuts in the material, and I have to wonder if it needs to be replaced.

I would purchase some aluminum tape and patch the holes.


I used the soudown mylar tape to join the panels together, and cover the corners. ran out. and ended up at HD and bought some of the aluminum metal duct tape to finish the job. I also used the 3m 90 spray adhesive to hold the panels to the bulkheads/overheads. worked well. in a few spots I had to use the fasteners. https://www.defender.com/product3.js...9105&id=940253.



i also used a large snap off razor blade to cut the foam and the plastic barrier. worked fine.




if anyone ends up doing this and needs some fasteners, PM me. we can make a deal I thought I would need more. but I did not.