Sound proofing

[sherlock]

Can anyone recommend the best way to sound proof the engine bay of a Bavaria powerboat fitted with twin diesels or recommend a suitable supplier of sound proofing material please?

Many thanks

 

[CPD]

I bought my a box of sheets of the stuff from Halyard. Expensive but works well.

http://www.halyard.eu.com/NoiseVibrationReduction/NoiseInsulationMaterials.aspx

 

[tobble]

for starters seal the compartment so there are no direct noise paths into the cabin or other areas you don't want to be disturbed. I guess neoprene hatch tape stuff with some sort of compression fittings would do this job. after that, you want to add weight to the walls, not fluff as is the common misconception. so maybe bond extra layers of ply to the inside of the bay. even better, as I have postulated before but never got round to trying, would be to make a sandwich of enigne bay wall -> foam - > sheet of ply, so you have a nice isolated mass to break the sound transmission path. prob cheaper than the sheets with lead in, and works on the same principle. you will also have a lot of noise transmitted though the hull as vibration direct from the engines which can be reduced by rubber engine mounts which presumeably you already have fitted. the other problem is that the prop shaft presents a nice vibration path and there's not a lot you can do about it! the only thing I can thing of is to put some stuff called constrained layer damping on the hull around the shaft, but I don't know where you can get the stuff! it's basically a self-adhesive sheet of rubber with a thick foil on the back.

hope that helps, sorry if it's a bit geeky, acoustics is my profession...