Suck or Blow?

Discussion in 'Sailboats' started by RHough, Nov 20, 2006.

  1. RHough
    Joined: Nov 2005
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    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    Is there a "best practice" for mounting bilge ventilation fans? Should the fan be close to the engine compartment and blow through a long duct to the outlet or should the fan be mounted close to the outlet and suck through a long duct?
     
  2. kenJ
    Joined: Jul 2005
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    kenJ Senior Member

    location

    Since all the "bad" fumes the fan is supposed to disperse are low it makes more sense to mount the fan high near the exit and suck through a long tube. Keeps any errant sparks from the fan motor from igniting the fumes you are trying to get rid of.
     
  3. RHough
    Joined: Nov 2005
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    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    Fair enough.

    The reason I ask is that most fans are better at blowing than sucking :)

    Thanks for the reply.
     
  4. Frosty

    Frosty Previous Member

    Not only that but if you blow the engine comartment all the smells and fumes will not necceserily go out the hole you want . it will also go through all the little holes and feed pipes spreading fumes throught the boat.
     
  5. messabout
    Joined: Jan 2006
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    messabout Senior Member

    Squirrel cage fans suck pretty good. Centrifugal paddle fans suck even better...Think vacuum cleaners. Conventional bladed fans do not pull air in as well as the other types unless they are tightly shrouded. Think Kort nozzle.
     
  6. yokebutt
    Joined: Aug 2004
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    yokebutt Boatbuilder

    Ought to suck about as much as it blows, you know, conservation of mass and all that pesky stuff.
     

  7. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    With a std 4 inch engine room blower I'm not sure you could measure the difference, but blowing is more efficent.

    However mounting any electrics as far above any possible water is the most rational.

    FAST FRED
     
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