Sunday, April 17, 2011

Generator Exhaust

     One of my goals with this boat is to enhance comfort through noise reduction. One way to do this is through acoustical isolation, and that is the subject of today's post. Those of you following along have probably noted that I mounted the A/C circulating pump on silicone foam pads, with great success (see the December 11, 2010 post). Continuing that methodology, I am mounting the generator muffler on isolation pads as well.
     The first step is to open up the 4 mounting holes on the muffler base, to approximately 1/2". Next, I fit rubber grommets into the holes. These are sized with a 1/4" central hole, which allows the 1/4" mounting screws to fit through easily. The purpose of the grommets is to isolate the muffler from the mounting screws in the horizontal plane, so that no vibration is transmitted from the muffler to the screws, and then to the hull.
     Next, my wife cut out some some mounting pads, using 1/4" thick closed cell silicone foam. These pads are trimmed to fit the corners of the muffler base, and are almost invisible once the muffler is placed on top of them. We used a 1/4" hole punch to make holes in the pads for the screws to pass through.
     Finally, we made some circular foam pads that are slightly larger than the stainless steel flat washers that are placed on top of the muffler base, and similarly punched a central mounting hole in these as well. These pads isolate the muffler in the vertical plane, with the result that the muffler is now in no direct contact with any rigid structure of the boat. The final installation looks like this:
     You can push the top of the muffler around about 3/8" of an inch in any direction, but it is still securely mounted to the boat, and is in no danger of coming loose. Lightly tapping on the muffler with a blunt object (I used my head) results in no vibration being transmitted to the hull. The final installation is shown in the following pictures. Note that all hose connections are double clamped, and that the discharge hose is installed with the highest possible arc, to prevent water reversion. As you can see, both the bilge discharge hoses, and the muffler discharge hose, are routed directly up and underneath the cockpit sole - the highest possible point. In both cases, I was able to increase the height of these hoses, as compared to the factory installation, by several inches.

     I will be detailing the generator installation soon, but in the meantime, here are a few more pictures of it, as it arrived:

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