Sound Down Question

[Tony Meola]

I need to put Sound Down in the engine box's to cut the noise down. I spoke with Steve at Sound Down and he recommended 1 1/2 inch sound down. I estimate I have 1 3/4 inch clearance between the top of the box and the top of the engine. I figure this is going to add about 22 lbs of weight to the box. \\I was also thinking of adding it on the inside of the bulkhead behind the seat cushions and in the bathroom behind the head.

My questions are:

1) is the 1/4 inch clearance enough given the heat from the engine?

2) Did the extra weight make the box that much heavier to open?

3) Has anyone used 1 1/2 inch on the top of the box and 2 inch on the sides of the box?

4) For those with Cummins, did you really notice a noise reduction?

Thank you

[Carl]

Tony-
I run gas motors...but its an Express, so I run the boat mostly from a position of standing on motor box...

The noise was getting to me so I did the sound insulation. It definitely cut the noise level.

What I learned-

Whatever level choice you go with...it is extremely important to get complete coverage cause the noise level really only drops significantly once every hole and corner is sealed. Amazing how much noise escapes from a small area.

The stuff is heavy and weight adds up quickly. Express the hatches really need to be lifted off to work on motors. The box is removed.. This is done by standing on motor from open hatch, dead lifting box straight up a 1/2" or so, sliding out from under side panels, then up again and back a few inches to place rear of box on deck...then stand behind box and tilt back. No insulation...the box was awkward. With insulation I had a hell of a time lifting and maneuvering. Tilting was a hoot, I'd get it started but weight of box with length had me at a teetering point ...almost a two man job, but only room for one.

Anyway, big difference, I liked....
...I say liked as pulling box and hatchs was also an issue in that the stuff is thick, it would rub and catch on motor coming out and going in...tears let water in, became heavier...tears let sound out becoming louder. Less then 100% proper prep on repairs had a piece falling once in a while so I lost that real noise reduction.
Had a Bad Back one day getting boat ready to go in...wound up tearing off a large piece when stuff snagged an exhaust manifold bolt and hole clamp...saw dumpster sitting there...I ripped it all out I was done.


Anyway...you don't have same box configuration as me, so should be better for you, but yes weight adds up. 22lbs seems very light for entire compartment...if you choice not to do entire, I'm not sure a little insulation is worth the effort. Kinda like closing car windows on the highway to hear someone talking...if you leave one open just a crack, its still about as loud as if it was wide open.

My .02

[Bruce]

The insulation does reduce noise and you will notice the additional weight but not unmanagable.

Being close to the engine will not affect the material.

On 31's you should also do the lower companion way panels below boxes and I also always did the forward bulkhead.
Don't just use contact adhesive as it will eventually fail leaving sagging insulation. Use both adhesive and the spike posts epoxied to the hatch with retainer caps.

[Tony Meola]

Carl & Bruce

Thank You. I am going to use both Contact cement and the pins. I was thinking of using 2 inch on the sides and the panels and 1 1/2 on the top. Not sure using 2 inch on the side will make that big of a difference but it should. Going to do the forward Bulkhead. Actually thinking about putting it on both sides.

Glad to hear the heat will not impact the foam.

Now to get good measurements, figure out how to lay it to make sure I have little waste and then order it.

Giving shipping charges I am debating if it is worth the drive to Mass or not. About 4 hours each way. Too bad I am no longer working. I could have combined a business trip in to one of the facilities up that way, or to our 40(k) vendor. Oh well.

[Yannis]

Tony,

I was about to chime in and confirm what Carl said, how important it is not to leave any crevice or any little corner uncovered.
The difficulty here lies in that you will have to remove/unscrew everything which is hung on the sides (racors, cables, etc) and re-install them OVER the insulation. Not just cut around them.

The sites describing the different materials suitable for sound insulation provide graphs showing the efficiency of insulation as per different thicknesses. If you take a look in the net you will see that the thicker the material the better the insulation. You will be able to find the "golden rule" by reviewing these insulating mats sites.

Also, for the right material choice, be careful not to confuse sound insulation with sound absorption materials.

Good luck!

[John F.]

Tony-

I used Soundown on the Anna E. (gassers) and on Crows Nest (diesels). What was said above in spot on. I used the foam w/vinyl sound barrier--the lead stuff is really heavy, and my engine boxes are heavy enough with the vinyl stuff. Especially Crows Nest where the boxes were lengthened about 11" for the Detroits. Use the pins. I sanded the inside of the boxes, mixed up some West with colloidial silica, and epoxied the pins in place. The newer Soundown has a peel and stick backing and its a lot easier to use than the spray adhesive they gave me the first time. Like Bruce said, insulating the companion way is key. I didn't do that at first with the Anna E., and was a little disappointed with the results. I then insulated the vertical companion way panels, and then made plywood horizontals that ran from the supports for the companion deck pieces to the engine beds to block off the noise coming up through the deck. Huge difference. I haven't done this on Crows Nest yet, but will. Good luck with your project. The Soundown guy in Mass. was really great to deal with.

John

[Tony Meola]

John

Did you use 11/2?

Yannis

Sound Down tells me I don't need to sound proof the outer hull so I really only need to work around the front bulkhead. Means working around some wires and the wash down intake line. That is why I am contemplating on putting on the inside of the bulkhead also. It will be covered by the seat backs and in the bathroom it will be behind the fiberglass panel and the sink cabinet.

I am going to do the final measurement this weekend and then order it then the install. Just want to make sure I have enough, maybe some left over but only some, not like, I really did not need that extra roll. Done that too many times.

[Yannis]

Tony,

I'm not a sound expert.
What I know though, is that to fight propagation of sound you need MASS and AIR TIGHTNESS. Failing to do BOTH will lead to mediocre results.
A perfectly soundproofed engine room that omits insulating the crevices where the box meets the hull, for example, will fail, because you lack air tightness.
Much like the car window example noted by Carl.
Similarly, an airtight engine room that lacks insulating mass to stop the sound waves from going beyond the walls, is equally ineffective.
Much like you can't stop sound with a plastic bag which is airtight alright.
I'm afraid that for a good result you either need these foam/lead/foam/alum lining sandwich material, or some sort of heavy rubber alternative. Heavy is the key word.
What you're saying about insulating the inside of the bulkhead is plausible ONLY if you can find a solution to the sound propagation through the plywood, in other words insulate the whole inside wall!
Also, if working "around" cables means that you leave exposed surfaces behind the cables, it defeats the air tightness principle...
For the sides I wouldn't know. But while you're at it, you might as well do them. Or you can do them later and notice any difference.

PS: Are you sure you want to do all this NOW? One thing WILL lead to another and you might end up watching happy people going fishing, from the yard!

[Tony Meola]

Yannis

I plan on covering everything possible. It is the out board hull dides they said I can leave undone. I guess the theory is it is pushing the sound outboard over the water and if you are running the sound should get lost out there.

I also figure I should be able to do a side in be day, and if I am not lazy and start at the crack of dawn do both. Need a cool day otherwise jit will be ,3 days.

[scot]

Not wanting to hi-jack a thread.. but this is a sound deadening question as well.

I have plenty of room in my engine bay and a couple of spare sheets of 1/2" structural foam coring, I am considering coring the inside of the box. So, the question is; will the 1/2" of foam coring, under a couple of layers of mat cloth reduce noise levels in the cockpit? I would think the space (thickness) created and the nature of the foam could absorb and reduce some level of resonance.

Thoughts?

[Tony Meola]

Scott

I am told foam will not do it, but you are running gas so you might just get away with it.

I know this is not a real comparison, but I just had all new AC put in the house. Air handler is in the attic over a bedroom. The AC guy set the pan on a 3/4 inch piece of plywood that had R5 green foam on top of it. He said to cut the noise of the air handler. I can tell you that it is dead quiet when it runs. All you can hear is the air coming out the ceiling vents.

[Yannis]

Scot,

IF we're talking about the same thing, I think that what you're referring to is a thermal insulation, not a sound insulation material.
Also it is rigid; I would assume that it is too stiff to manipulate around bends and corners.
Google it and you'll see its properties.

[John F.]

Tony-

Its 1 1/2" as I remember. With the vinyl sound barrier. Not lead. Order lots of those little pin things and their caps. And tape for the seams.

John

[scot]

It's the stiff, ridged hi density structural foam (dark green). It may be dyvinacell ? or Klegicell? It will bend slightly and is much more moldable with a heat gun. Mine is 1/2". The generator example is encouraging, that sounds like the foam I have. If I recall, it was $100+ per sheet 10 years ago.

[Yannis]

Scot,

The generator example, if I understand correctly it is Tony's A/C example, is not relevant!
What this ply/foam combo probably did is it reduced vibration, not the sound. The sound is probably not important and it's one floor up so it's not heard anyway.
As for your material, I still think it's a thermal insulation material. Heat it and you destroy its properties because you'll reduce its air bubbles, let alone that you should not smell its fumes, if any...
$100 per sheet ? Holy cow, I don't know of any such thing...

[Navatech]

What this ply/foam combo probably did is it reduced vibration, not the sound. The sound is probably not important and it's one floor up so it's not heard anyway.

Yannis, sound IS vibration!... Reduce the vibrations and you reduce the sound... Just ask any submariner (who's very life depends on reducing sound)...

[Yannis]

By vibration I meant the actual shaking/moving of the machine, not the sound of it.

[Navatech]

By vibration I meant the actual shaking/moving of the machine, not the sound of it.

I know what you meant... You can cover, for example, a generator with a sound proof box but you'll still hear/feel the vibrations in the V berth if the generator isn't properly isolated from its base... You can somewhat hear my generator if you're in the cockpit... Much of that comes through the exhaust... However, if you go to the master cabin or the V berth you need to put your ear on a structural surface (like a wall) to hear anything... And even then, what you hear is a very faint humming...

[Tony Meola]

Tony-

Its 1 1/2" as I remember. With the vinyl sound barrier. Not lead. Order lots of those little pin things and their caps. And tape for the seams.

John

John

will do.

[Capt.Frank]

The biggest problem I have had with the sound down is the edge pulling back even with the tape. On a new fire engine the manufacturer used seam sealant on all the edges to seal the edge and hold edge secure. Once I get my washboards done. Next list of projects.

[scot]

As for your material, I still think it's a thermal insulation material

It's "Klegecell".. I looked it up. It is a structural foam used in boat construction for coring, i.e. sides, bottom, etc. It's not a thermal thing. It was, and is a mainstay in boat building industry. There are a few variations on the material, relating to density, stiffness and weight. It was, and is used extensively in T-tops and hardtops for thickness and strength. It can bend with a bit of heat, the resin infuses (soaks in) into the contact side of the foam sheeting and it becomes very stiff. Combined with altering the structural profile of the laminate vs just glass layers.. the structure becomes very strong.

I may give it a shot as I need the side wall stiffness in the stretched engine box. If it cuts down a little noise it's a bonus.

Thanks