Making waves to increase stability

Discussion in 'Stability' started by Leo Lazauskas, Sep 24, 2013.

  1. Leo Lazauskas
    Joined: Jan 2002
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    Leo Lazauskas Senior Member

  2. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Nowt new here, but a new application :)

    Their model testing was with Hs=2m..not a lot for a vessel that size anyway!
     
  3. Leo Lazauskas
    Joined: Jan 2002
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    Leo Lazauskas Senior Member

    Good number, John.
    I suspected they were testing in smallish waves, hence my comment about
    "real seas".
    They would have to pump a lot of water around quite quickly to counter the
    size of seas the ships might operate in near Norway!
     
  4. Yobarnacle
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    Yobarnacle Senior Member

    http://www.ottocandies.com/index.html

    Candies has included Frahm anti-rolling tanks in their vessels for at least 20 years.

    http://en.wikipedia.org/wiki/Antiroll_Tanks

    "U-Tube Tanks[edit]

    The use of these tanks were pioneered by Frahm in Germany during the turn of the 20th century and they are often referred to as Frahm tanks. These partially filled tanks consists of two wing tanks connected at the bottom by a substantial crossover duct. The air column above the liquid in the two tanks are also connected by a duct. As in the Free Surface Tanks as the ship begins to roll the fluid flows from wing tank to wing tank causing a time varying roll moment to the ship and with careful design this roll moment is of correct phasing to reduce the roll motion of the ship. They do not restrict fore and aft passage as space above and below water crossover duct is available for other purposes."


    Some of Candies vessels pictures below
     

    Attached Files:

  5. El_Guero

    El_Guero Previous Member

    Leo,

    Would this give the rest of us an advantage? I do not plan on being in bigger seas.

    :)

    wayne
     
  6. philSweet
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    philSweet Senior Member

    Here's a neat survey of antiroll gadgetry.
     

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  7. BMcF
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    BMcF Senior Member

    Unfortunately, that report was incomplete and outdated from he moment it was issued; not the fault of the authors really, because the real advancements were all being made in arenas (fast ferry mainly) in to which they had almost zero visiblity or awareness of.

    Not a bad overview but many of the author's comments or conclusions about application and effectiveness were way off the mark when compared to the actual state of the art in ship motion stabilization in 1990.
     
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