Offshoreonly.com - sound isolation?!? need help

Tim

Sounddown has technical papers available that do an excellent job of describing the different types of acoustical barriers and acoustical attenuating materials available. For your application you may want a combination of the two.

On your bulkhead, you definitely want a "barrier" which will be a foam base containing a dead soft suspended barrier material with significant mass. The lead sheet works best, with the suspended vinyl sheet being a close second. For the sides of your engine compartment you may wish for an acoustical attenuating material. This material does nothing to "stop" sound energy, it simply traps a lot of it and keeps it from echoing around. Soundcote makes a butyl covered foam that works well for this application (and it is lightweight).

You may also wish to add automotive headliner material to your cockpit cover as it will quiet the cockpit significantly.

I've reduced the sound level at cruise at the helm of my diesel cruiser by 6 dB. That's half, twice. And it wasn't exactly loud to start with, just louder than I wanted. Before doing this, i never heard the exhaust noise. Now all I can hear is a cool little remnant of turbo shriek coming out the transom corner air intakes and a pleasantly muffled exhaust noise. At docking speeds can hear the turbos "idling" instead of mechanical clatter.

I can even go INTO the engine compartment with them running without thinking I'll be deaf before I can crawl out. Before, all of the clatter echoed around retaining its energy, whereas now it is trapped and absorbed on every large surface. I was very pleased with the results.