Engine Box Noise Reduction

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prjacobs
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Joined: Fri Oct 12, 2012 4:06 pm

Engine Box Noise Reduction

Post by prjacobs » Mon Feb 09, 2015 11:10 pm

My latest project has been to reduce some of the noise from the engine box that houses my Yanmar 2GMF 20 Diesel engine.
I've used 1" (25mm) sheets of Foam Sandwiched Mass Loaded Vinyl Barrier with a vapor barrier on one side. I used these directions as an installation guide.
Cardboard templates were made for each piece, allowing for the actual thickness of the material.

To affix the sheets to the inside of the engine box a spray-on adhesive combined with "pins" epoxy'd to the inside of the fibreglass box were used.
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All insulation sheet seams and edges were taped with HVAC aluminum tape.
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This sound deadening material adds a bit of extra weight to the boxes, but this only proved an inconvenience when transporting them to the boat and fitting them through the companionway opening.
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The Yanmar has a fuel filter bolt sticking out on the starboard side so I needed to notch the wood frame on the forward box to get it to fit. Other than that, once inside the cabin, they were relatively easy to slide into place.
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Approximate weight of the material is 4.8kg/m² (1 lb/ft²). Amount used on the rear box was 0.73 m² (3.5 kg) and the front box 0.69 m² (3.3 kg), for a total added weight of about 6.8 kg (15 lbs)

Being concerned about possible heat buildup in the engine room I've installed a remote heat sensor on the inside of the box.
I have only run the engine at the dock, but noticed an immediate reduction in noise. Next job is to test it under way, with the Admirable along for a second opinion. :)

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