sound dampening / insulation

[wca_tim]

what experiences have folks had minimizing engine and drive train noise using sound insulting panels, spray on sound absorption, or any other strategies? Thanks in advance for any thoughts or advice. I'm not talking about exhaust sound...

 

[erikgreen]

Re: sound dampening / insulation

Dynamat is made to both absorb sound from engines and mechanicals, and also to dampen the resonance of panels it's attached to.

Iboats also sells a kit of rolled sound dampening material I think.

Erik

 

[oops!]

Re: sound dampening / insulation

hello again.

i did a thread on this one a little while back.

dyna mat is the item of choice.

ive used everything except that....

old sea ray....6 cyl...doghouse...jump seats...open gunnels to the front...

i re cut wood to form a solid barrier from the inside motor area...to the passenger area.....used pink solid foam...(2ins) on the back of the plywood.

then i screwed acoustical celing tile to the foam. (bad idea..it gets wet)...and gave the same treatment to the doghouse.....a real hack job as you can see....

it cut the sound 50 % for the first month....till everything got wet...

now in fabbing a full enclousure to the motor area......gonna use plastic....10 mil....then dyana mat....then another sheet of plastic.....

(if youve ever been on a construction site when theyve added vapor barrier....poly is a super sound reduction item. sound waves bounce off them and not thru)

im hoping i can get a 75 % reduction....i dont wanna hear the engine at all unless wot.

cheers
oops

 

[Bondo]

Re: sound dampening / insulation

(if youve ever been on a construction site

Ayuh,....... What I've found to work Great for sound reduction is,.........

Packing Foam found when Dumpster Diving at a jobsite.......

It's used in sheets of white foam, usually about 1/8" thick, for packing all sorts of stuff,.....
And it's as Waterproof as any Foam gets........
The Bigger the Stuff,.... The bigger, wider the sheets,... Sometimes Thicker too....

I stapled it to the motor side of the plywood cover,+ it's stayed real well,... Except for where the pulleys or belts hit it.......
On the outside of the motorbox,... I stapled another layer,+ covered it with vinyl fabric.....
I also used the same foam to line the sidepanels I built,..... A layer of foam,+ covered it with vinyl fabric......
In the open areas that needed curtains,..... I added a layer of the same foam in-between the layers of vinyl......

 

[onenomad]

Re: sound dampening / insulation

I don't know how involved you want to get, but when I changed motors (small diesels), I used a 1/2" plywood product with a sound barrier laminated in the middle of the plies. I can't remember the product name, but it was manufactured in Albany, Oregon. I would think that a google search should locate it. For me, it reduced the sound level by about 50%, maybe more. If you are using a gas motor, it should be very effective. Good luck with your project.
Gerry

 

[onenomad]

Re: sound dampening / insulation

The name of the company that I mentioned in my previous post is: Plywood Components Inc, Albany Oregon. They do have a website, and I think they sell nationally.
Gerry

 

[wca_tim]

Re: sound dampening / insulation

Thanks for the ideas. I was planning on getting a roll of dynamat for the under side of the engine hatch (I've got a 33" x 65" hatch over the engine bay), and perhaps to line the sides or front of the engine compartment.

I found a company in the next town over that makes and sells a product called "accoustaply" which is exactly what you're referring to onenomad. Since I'm doing the seats, I'd like to get a sheet of it to use for the back seat construction and then then use construction foam behind that where it won't be obvious. The acoustaply is like 300 for a sheet though.... maybe it would be better to buy a bigger amp for the stereo instead...

 

[wca_tim]

Re: sound dampening / insulation

I stapled it to the motor side of the plywood cover,+ it's stayed real well,... Except for where the pulleys or belts hit it.......
QUOTE]

My biggest fear of sticking something like dynamat to the underside of the engine hatch is flying along and and having all hell break loose under the engine hatch when the dynamat it sags a bit, get's caught up in the pulleys and belts...

 

[onenomad]

Re: sound dampening / insulation

On using the specialty acoustic ply; every cut you make almost stops your heart beat. Measure, measure, measure. Layout, layout, layout. Then, cut once.

 

[Capt. Mike]

Re: sound dampening / insulation

you better watch what you use, you could be setting yourself up for a bad fire

 

[Caveman Charlie]

Re: sound dampening / insulation

I stapled it to the motor side of the plywood cover,+ it's stayed real well,... Except for where the pulleys or belts hit it.......
QUOTE]

My biggest fear of sticking something like dynamat to the underside of the engine hatch is flying along and and having all hell break loose under the engine hatch when the dynamat it sags a bit, get's caught up in the pulleys and belts...

you better watch what you use, you could be setting yourself up for a bad fire

Those are my fears too. I need to come up with something myself. My boat originally had something on the inside of the engine cover that looked like fiberglass insulation. It was yucky and I ripped it off.

 

[Zetman]

Re: sound dampening / insulation

I'm using a sound damping/heat reducer I found at JC Whitney just search for sound proofing

 

[JAL51974]

Re: sound dampening / insulation

zetman- how has that stuff held up for soundproofing?

 

[wca_tim]

Re: sound dampening / insulation

Anybody tried the spray on sound damping undercoating?

The high dollar wood laminated sound proofing stuff shouldn't be any more of a flammability issue than the wood you're replaceing with it.

When I rip things apart this time, I'm going to paint the engine compartment and am going to do the sides and front, and probably the underside of the engine hatch as well with sound damping rubberized undercoating and see if that does any good. Even if it diesn't help with sound much, it's durable tough stuff... and my engine compartment is black anyhow...

next from that if still noiser than I want is the dynamat made for high heat areas...

 

[reelfishin]

Re: sound dampening / insulation

Dynamat can be held in place more securely by using strips of aluminum or wood every so often to secure it. My problem with Dynamat is it's weight.
I custom re built an engine box on a buddies boat and used that pink 3/4" foam to insulate it and to kill some noise, it worked very well and has never absorbed any water. I did two layers with some air space in between on top, the motor was almost completely silenced that way. I covered the foam in all crucial points with some Tyvek type sheeting and used huge plastic washers and stainless screws to secure it all. It was a far cry better than the original glued on fiberglass insulation that had fallen down and been mauled by the belts and pulleys several times. The two jump seats were now usable without scolding anyone in shorts and the motor noise was reduced by more than half. He also upholstered the outer box with foam and vinyl as well which added even more sound deadening to it.

 

[oops!]

Re: sound dampening / insulation

i havent tried the spray on....but im gonna try it all !

including bondo-s dumpster diving...i know what material hes talking about....its like pool noodles....from what i know about sound...that would be good stuff.


tim....i dont know the properties of dynamat, but i was looking at it, at a local sterio store.....looked a lot like pond liner.....the kind you find in gardning centers


one of the tricks im also gonna try is putting a small layer of rubber between the deck joists and the deck.....that way the motor sound wont travel thru the stringers and frames and reverberate to the passengers...

btw....hows the power plant comin?

cheers
oops

 

[i386]

Re: sound dampening / insulation

Dynamat Technical Specs.

 

[oops!]

Re: sound dampening / insulation

Dynamat Technical Specs.

thanks...you just gave me and idea

 

[i386]

Re: sound dampening / insulation

I should have linked here. It has the specs for all their products, not just the original.

 

[wca_tim]

Re: sound dampening / insulation

Looks like I'm going to try rubberized spray on undercoating on teh sides of the engine compartment and bilge area (black already) and on the underside of the hatch. Add either dynamat or dumpster retreived materials aka bond-o to the back of the back seat (front of engine compartment), and see how that does... Not sure why I'm going to bother at all. With the short amount of space for exhaust and the length of the risers needed to avoid sucking water back into the engine cammed the way it is... it's not going to be quiet when running no matter what....

powerplant? OH, you mean this one? has come a ways since that picture, almost to the point where I'll have everything lined up to take 2-3 days off to swap engines out and redo the engine compartment in the middle.