Lateral motion by twin waterjets

Discussion in 'Jet Drives' started by telrunya, Sep 6, 2011.

  1. telrunya
    Joined: Sep 2011
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    Location: Singapore

    telrunya New Member

    Hi all

    I'm interested in using twin waterjets and I'm curious on how it provides a lateral thrust to the boat without yawing.

    Can anyone explain what's the combination of machineries (i.e. nozzle, bucket, throttle) that produces a lateral thrust to the boat?

    Thank you!
  2. BMcF
    Joined: Mar 2007
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    Location: Maryland

    BMcF Senior Member

    It's a simple vector addition. Typically, both jet units are turned outward/outboard and one placed in forward and one in reverse. The fore-aft thrust vectors cancel and you are left with only the residual combination of side thrust vectors, which side direction depending simply on which unit is in the forward bucket position and which in reverse.

    I had a simple diagram somewhere that shows what I described above. I'll try to find it.
  3. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    The large catamaran ferries here use such a system.
    Nozzles and buckets are articulated by hydraulics, but the actual controls are electronic: Two joysticks, each controlling one jet and the corresponding engine, plus a lock/unlock switch for normal navigation and docking.

  4. powerabout
    Joined: Nov 2007
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    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    not great though as many of the large high speed ferrys have smacked the dock
    For their windage they need something more
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