Our Perkins 4-108 is located under the companionway steps right next to the galley and quarter berth and is fairly noisy. There is existing insulation, but it’s now over 40 years old. When we did the sea trial, we used a free phone app decibel meter and clocked the noise at around 80 dB. And like most engines it also heats up the inside of the boat.
The existing insulation is some sort of acoustic ceiling tiles. We considered removing them, but opted to just add new insulation over the top. We chose a self-adhesive, foil-lined sound deadening foam from McMaster Carr. We used the same free decibel app to test the before and after and didn’t really see any difference; however, we could certainly hear a difference. It sounds much quieter now.
One concern we have is ventilation for the engine room. We have a vent hole in the cockpit that we screw a cowl into when we run the engine. We also have a bilge blower, but it’s not vented properly and doesn’t do much at this point. Hopefully, we haven’t created an overheating problem by adding more insulation. We’re going to wait and see.
Here’s a quick video of what we did.
