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Silent Running


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I doubt you could spray it. If you can, the technical info should tell you how and you would be looking at high pressure airless application I expect. Are you intending to use it on steel/ally? These products are often trowel on types of products. The work by dampening the material you apply it to, to stop noise ringing through the Hull.

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I’ve tested a similar product and it made no noticeable difference – albeit it was a wall in a building rather than on a boat. I agree with Wheels in that it’s a dampening material. I’ve seen a supplier’s video where a paint-on product appeared quite effective. However, the resonating surface was very thin and flexible and lent itself to any form of dampening. For something heavier and stiffer (boat hull or engine for example), the same product would be tits on a bull. If you’re keen, I’d be asking for references from the supplier and follow those up.

 

It’d also be worth considering what’s making the noise in your situation. Is it airborne, in which case dampening the source would be effective, or structure borne, in which case it would not.

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My engine sits under the cockpit in an enormous open space (transom is 6 ft across) and the engine noise reverberates. I painted the entire area last winter with a primer, which made an appreciable difference. I'm thinking the Silet Running paint would be a relatively-cheap experiment compared to the sound-proofing sheets, which I estimate would cost me $1000 in materials alone.

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It's one of those situations where you would have to suck and see. There are too many unknowns for any of us to comment accurately enough.

There are two ways sound is transmitted. Mechanical, which is vibration through solid objects and those objects vibrating create sound. And Acoustic, which is Air pressure. The problem with acoustic transmission is it is all about Air pressure. If there is a hole somewhere, then Sound gets through. Certainly both the paint or the batt stuff absorbs a certain amount of the energy and either will certainly help lessen, but there is no way any of us could guess as to just how much.

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compared to the sound-proofing sheets, which I estimate would cost me $1000 in materials alone.

 

Perhaps try the likes of Forman Insulation or an automotive supply place such as Autodec in East Tamaki. There's a number of sound deadening foams around that are a fraction of the cost of the foil/lead/foam stuff sold over the counter at the chandlery and im sure they would work considerebly better than a paint on system. I redid my engine compartment for less than a few hundred bucks with underbonnet automotive foam.

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Hi Tuffy, what difference did it make?

 

Hard to say as it was done along with a number of other improvements in the engine compartment including sealing up some gaps where noise was escaping.

 

We can now have a normal conversation down below with the engine at full revs whereas before you'd be yelling

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An engine is usually in a pretty well sealed compartment. There are two things to do to reduce the noise you get outside the compartment.

 

1) absorb the sound energy in the compartment - you need to put some soft stuff in there to absorb the sound. The thicker the soft stuff the lower the frequencies it will absorb. If you don't have any soft stuff in there, the sound level in the cavity just keeps on building up (ie it gets louder) until the energy transmitted from the cavity by vibrating the walls balances the sound energy being produced by the engine.

 

2) stop the sound energy from coming out - you need heavy walls to stop sound transmission - lead or concrete are effective, but not ideal on boats. Cavity walls with soft insulation material in the cavity can work better than nothing, and if the faces are isolated from each other (box within a box) then that's even better.

 

All of this could be useless if there is transmission of vibration direct from the engine to the boat structure - then it's not the engine making the noise, but the whole boat.

 

A paint could be effective at reducing some particular resonance, but otherwise I can't see how it would be very useful on any reasonably thick substrate.

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A paint could be effective at reducing some particular resonance, but otherwise I can't see how it would be very useful on any reasonably thick substrate.

 

The paint is not as you think of paint, only in that it is a thick liquid you coat on. Often using a trowel or a sprayer designed for super thick stuff. It dries to a dense rubbery substance and due to it's weight, it dampens sound by poorly transmitting and dampening sound energy.

 

bbay, yes you could use a system you describe, but you need a good amount of amplification and a really good wide range speaker and a good microphone. Not really suited to Boats, but now a common thing in some high market cars and inside Airport lounges.

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