soundproofing core material

Discussion in 'Materials' started by Rick375, Aug 19, 2019.

  1. Rick375
    Joined: Aug 2019
    Posts: 2
    Likes: 0, Points: 1
    Location: Newburyport

    Rick375 New Member

    I’m going to re-core the cockpit on our 31 Pacemaker this year and I’m wondering if there is a good core material that will help with soundproofing and be structurally sound. Trying to kill 2 birds with one stone if possible. Any suggestions I know I’m not going to completely eliminate sound. I have little to no space between my engines and the hatches so if I can use a core material that helps with sound deadening, it will help to quiet them down.
     
  2. Yellowjacket
    Joined: May 2009
    Posts: 611
    Likes: 90, Points: 28, Legacy Rep: 447
    Location: Landlocked...

    Yellowjacket Senior Member

    No, you can't kill two birds with one stone in this case. Sound will bounce off the hard outer surface, the core isn't moving or absorbing sound. The stiffer the sandwich the more it will resist letting sound in. So if you're looking to keep sound out then that's good. Any sound absorbent material isn't going to be stiff enough to be a structural core. In the case of interior generated noise it's important to have soft walls with sound absorbent material in that soft surface. The harder the surface the more sound bounces back into the cavity. Higher frequency noise is attenuated by blocking the sound path. Low frequency noise is stopped by mass. But to some extent very stiff surfaces act a bit like heavier surfaces because they don't move as much in response to sound waves. Still, the rules still apply.
     
  3. Rick375
    Joined: Aug 2019
    Posts: 2
    Likes: 0, Points: 1
    Location: Newburyport

    Rick375 New Member

    Thank you Yellowjacket. That’s all I was looking for. So the best way to block the sound would be a soundproofing material between the engine and the hatch. From what I’m understanding is that with a fiberglass outer layer, the core material won’t matter.
     

  4. Yellowjacket
    Joined: May 2009
    Posts: 611
    Likes: 90, Points: 28, Legacy Rep: 447
    Location: Landlocked...

    Yellowjacket Senior Member

    Yes the problem with adding a box around a sound source is that while the box walls decrease the sound level outside the box some, if the box is "hard" on the inside, the box actually increases the sound around the engine. So, if for instance, you have an engine that emits 85 db without a cover around it, and then put a box around it that has a 10 db reduction, the sound pressure level inside the box could go to 90 db and the noise level outside the box goes to 80db. Instead of getting a 10 db reduction from the box like you would expect, you only got 5 because of the increase This is why it's important to add sound absorption material inside the engine area. And that also means not just on the hatch where most of the sound is coming out, it's important to reduce the reverberation inside the engine area. That means even surfaces like inside the transom. This means all of the walls inside the engine room being treated will pay.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.