Intact Stability - Weather Criteria USCG-DHS

Discussion in 'Stability' started by Niru, Mar 25, 2014.

  1. Niru
    Joined: Jul 2010
    Posts: 50
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    Location: Philippines

    Niru Mr.

    Good Prime Meridian!

    From attached file Criteria.jpg, H = vertical distance in feet/meters.

    From other attached file Barge.jpg (assume without load)

    is the value of H =

    a.)black line to green line (bottom plating to upper deck plating)

    b.)magenta line to red line (center of underwater body to center of freeboard)

    ...cause if the case would be a.) regardless of the loaded draft value of H is constant.

    ...for case b.) makes more sense. since value changes at every different draft

    can anyone clarify this?

    Thanks peeps!
     

    Attached Files:

  2. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    I think "center of underwater area" refers to the centroid of the projected lateral area below the waterline, and it changes as the draft changes.
     
  3. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    It comes from the excellent paper by Sarchin & Goldberg.

    It is the distance from half the draft to the centre of the projected area that is above the waterline. So the more superstructure/deckhouse you have and with more tiers (decks), the greater the distance to the centroid of "A". Basically the higher the superstructure/deckhouse the greater the effect from wind on rolling and hence stability.
     
  4. Niru
    Joined: Jul 2010
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    Location: Philippines

    Niru Mr.

    @ DCokey ... when we use the term "centroid" it refers to the central part of a volume.
    in other words the Center of Bouyancy above keel.

    @ Ad Hoc. Copy!
     

  5. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    Centroid can be used with either two dimensional or three dimensional shapes. "centroid of the projected lateral area" from my response above refers to the centroid of a two dimensional shape, the "projected lateral area".
     
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