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Capt. Patrick or Bruce, I was told that 80% of engine noise from a running deisel was coming from the air cleaner / turbo area of the engine, is this true and ifso what could I do to slow up the sound?

Brewster,

A significant amount of higher pitch noise comes from the turbos once they kick in. The only way to reduce all engine noise is to install as much sound proofing to as many engine compartment surfaces as you can. Not just under the engine box itself, but also the forward bulkheads, the drop panels, under the wings, & the hull. The more surfaces covered with sound insulation material, the more the sounds will be absorbed. Sound hitting a hard surface is just magnified...

I used almost two full boxes of insulation on "Buddy Boy" and it's very quite, even at full throttle. Granted, the Yanmars are quiter to begin with than most other engines, especially Cummins.

Another source of noise comes from equipment that is bolted to the boat but not isolated from vibration. For example, Bruce & I usually double insolate generator mounts. Gen sets always have factory installed rubber isolators between the mounts and the catch pan. Most people just mount the pan directly to the shelf. We add additional rubber pads between the pan and the shelf.

Br,

Patrick

I Had not insulated the bulk heads or some of the other spaces around the engines. I did the boxes and that was good I will start to do out the rest of the spaces. Thank you very much.