I have been on
@swatski boat and the insulation did make a difference in the amount of engine noise. I have also added insulation but not in the bilge area and not to the degree of
@swatski . Mine is all focused on insulating the cabin from the engine and bilge with automotive/marine grade stuff intended for this purpose. My insulation does not make as big a difference as
@swatski. Neither mine nor
@swatski make a giant difference. I would say more like stuffing a towel under the bottom of a door than shutting a door. The biggest difference is just filling the poor manufacturing gaps between the engine/bilge compartments and the cabin along with adding a seal to the engine hatch. Those things should not cause extra heat for the water cooled engines.
I do notice engine heat soak in the middle of the summer. Keeping the blowers on for a few minutes after shutting down the engines or opening the engine hatch helps. If getting sand/silt in the cooling passages that would certainly impact things. Add that build up to the overkill insulation and extended high rpms at low speed and it may have just been a perfect storm. Water (not air) is still the main cooling method and thermal energy transfer happens much faster with water than air. I would lean far more towards any issues with the cooling water intake system, oil cooler, or exhaust manifold than towards the insulation being the root cause. Heat deforming foam sheet packing material does not take much heat. Also sometimes stuff just breaks and
@swatski may just have very bad luck with his current boat.
@swatski deserves some good boating luck.