Additional Silencing

Discussion in 'Sterndrives' started by Willallison, Jul 20, 2010.

  1. Willallison
    Joined: Oct 2001
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    Willallison Senior Member

    Is anyone aware of any additional silencing that can be installed on a sterndrive installation?
    In this case a Mercruiser 4.3 MPI
     
  2. Myoung42
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    Myoung42 Mechanical Engineer

    What is the source of the engine noise? Is it loud through the underwater prop exhaust discharge? Is it through transom exhaust? Perhaps marine mufflers are an option. They're space hungry though...

    How about tight seal around the engine hatch? Gaps introduce ventilation for sure, but they also let much noise through. You've probably already considered both of these..just some ideas from a novice to a professional.

    Quite a design company you have there by the way. Graphite is quite a looker!
     
  3. Willallison
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    Willallison Senior Member

    Thanks for the kind words Mark:)
    There is no source of engine noise at the moment... One of the primary requirements for a design I'm working on at the moment is that the vessel be quiet.
    I will, of course, be doing all the things you suggest, external to the engine - insulation etc. But was wondering about products / systems for the donk itself...
     
  4. Myoung42
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    Myoung42 Mechanical Engineer

    What do you mean by donk?
     
  5. Willallison
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    Willallison Senior Member

    :D Sorry - Donk is Australian slang for motor...
     
  6. FAST FRED
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    www.soundown.com/sitemap.htm

    A good source of a variety of products.

    Remember a box over the engine will need an engineered non reflective path intake duct to feed the unit.


    There are also USCG approved thick paints that absorb sound .

    The 2 inch thick 2lbs per sq ft lead sheeting 360 deg in engine box is best.

    FF
     
  7. gonzo
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    gonzo Senior Member

    There are two basic ways to diminish the noise you hear from an enclosed compartment. One, you line it with absorbent material. Two, you make the noise exit away form you,(an opening). You can combine both.
     
  8. CDK
    Joined: Aug 2007
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    CDK retired engineer

    The noise level in passenger cars dropped a few dB when car makers installed a large plastic cover over the engine, mounted on 4 or 5 rubber grommets.
    It is common now on all cars except the cheapest.
     

  9. powerabout
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    powerabout Senior Member

    Most of the noise comes from the induction which is not designed to be quiet like a car.
    Merc fitted a kit to 454 inboards many years ago. It comprised of a housing that went over the flame arrestor to allow for a hose connection and had a meter of flex hose with an aluminium bell mouth in the end.
    It made a huge difference to quieting the induction noise
     
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