Engine noise insulation

JohnInBKK said:

Interesting thread.
Coming from sailboats, I really want to reduce engine noise throughout. Sure, there are plenty of soundproofing "sheet" materials out there, which the manufacturers attempt to market with features such as "self-adhesive" etc, but the fact remains, the engine room walls are cluttered with pipes, cables, pumps etc. etc. So, bearing in mind that there should be no gaps, without significant work - removal of ALL (wall, ceiling) fixed appliances - a tidy and successful soundproofing solution in the engine room surely cannot be achieved using sheet materials... Thoughts?

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I was thinking the same thoughts John. It would be virtually impossible to box off my engine compartment in sheet soundproofing material. It is a small area with a proper "wall" only on one side.
However - after thinking about it. I wouldn't want to get a perfect seal as it would cut off air circulation. I only need to have a soundproof barrier between the engine and areas where people are.

The way I see it, I plan on first concentration on getting good soundproofing on the underside of the deck and hatches. There is minimal accessories attached above the engine other than wiring harnesses, which are easy to rerun on top of the soundproofing.
Next, I'd concentrate on ensuring there is a good seal on all hatches, using good weatherstripping.
I feel that these two areas will give me the biggest bang for my buck. The sides are less important unless it is a direct barrier to a lower living area. Most of the side areas would benefit with something to absorb noise, but having a complete seal is nowhere near as important as with the barrier above the engine.

JohnInBKK said:

So, bearing in mind that there should be no gaps, without significant work - removal of ALL (wall, ceiling) fixed appliances - a tidy and successful soundproofing solution in the engine room surely cannot be achieved using sheet materials... Thoughts?

Click to expand...

I did the significant work. I used sounddown sheets over silent running paint. It was very successful.

The little Albin 25 was light years ahead in engine noise and more. The engine is in a compartment (sound insulated). The compartment has a top (about 75% of the compartment) and a bottom. There is a rubber seal around the base of the top part and it hinges as does part of the cabin bulkhead .. to accommodate the eng com top to swing open. Anything that falls or drips off the engine goes into the bottom of the compartment and it is gel coated white on the inside. So cleaning is a snap and even very small engine parts can be clearly seen and reached. The compartment is air tight except for the 2 holes in the side of the engine beds that lead aft through the engine beds and beyond to the transom ... up the transom to the vents on the aft deck. All the air in the engine compartment comes through those two vents. Diesel smells inside the boat are greatly reduced and engine heat is kept mostly outside the boat.

Once you've had an A25 (built in Sweden) all other boats are something less. There is much else to admire in the A25 design too. If I sound like I wish I had my A25 back ..... there is more than a little truth in that.

Please give a thought to the flammability of the materials you are planning to introduce to your engine compartment...

Go into your engine room and turn off the lights. Every where you see light coming in sound is getting out. Plug those holes first.
You will be amazed at how much that little bit does to reduce the noise.

The Iphone has an app to measure decibels. Great little diagnostic tool for measuring sound.

SD

I did the significant work. I used sounddown sheets over silent running paint. It was very successful.

By chance did you operate any time JUST with the paint?

Did it work???