Height of exchaust outlet

Discussion in 'Boat Design' started by Tharayman, Dec 21, 2020.

  1. Tharayman
    Joined: Dec 2020
    Posts: 11
    Likes: 0, Points: 1
    Location: North cape

    Tharayman Junior Member

    The outlet pipe for the motor is not every high above drck. About 2 meters. On days with little wind, and days with the "wrong" wind direction it feels like we are breathing in substantial amounts of exhaust gasses. Not very nice.

    Would it help if I put up a higher pipe? Let`s say 3 meters. I am getting images in my head of the tall factory chimneys spewing blsack soot over London during the industrial revolution. Did they manage to get rid of it, or did the gases just come falling down on them?

    IMG_4310.jpeg
     
  2. Benjamin
    Joined: Dec 2020
    Posts: 11
    Likes: 3, Points: 3
    Location: Florida Keys

    Benjamin Junior Member

    Just put it under the waterline on the transom. As long as you have a valve/flap on it to keep water from coming back in you will be fine and have a much quieter ride.
     
  3. kapnD
    Joined: Jan 2003
    Posts: 840
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    Location: hawaii, usa

    kapnD Senior Member

    Underwater exhaust is not that simple.
    You’ll find some excellent advice on this subject at sbmar.com.
     
  4. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    A higher pipe will help. Underwater exhausts can cause a lot of new problems if they are not designed properly. Among other things, the increased backpressure will reduce the HP of the motor.
     
  5. Benjamin
    Joined: Dec 2020
    Posts: 11
    Likes: 3, Points: 3
    Location: Florida Keys

    Benjamin Junior Member

    If it was on the transom, It wouldn't really be an underwater exhaust whenever the boat is moving. Wouldn't that mean that there wouldnt be any change to the backpressure?
     
  6. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    I don't think anybody can say without some photos of the boat at rest and underway.
     
  7. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    It being a dry stack exhaust, KISS method would be to raise outlet height.
     

  8. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    I agree.
     
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