Static stability(Academic problem)

Discussion in 'Stability' started by diegoperrera, Oct 1, 2014.

  1. daiquiri
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    daiquiri Engineering and Design

    And especially once on the sea floor, they tend to become pretty stable. :p
     
  2. sharpii2
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    sharpii2 Senior Member

    Only if it's a submarine. And only if its Center of Gravity (CG) is below its Center of Buoyancy (CB).

    This "Barge Ship", with its stack of three or more blue boxes, meets neither of these two criteria.

    With three blue boxes stacked on top, the deck will go under, then the hull will capsize, and either dump the blue boxes, or be pulled down to the depths with them.
     
  3. Nick_Sinev
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    Nick_Sinev Junior Member

    cmckesson is absolutely correct. Six boxes

    sharpii2, you've done a mistake in your calculations. In case of six boxes the deck of the barge is still above the water.
    The deck is exactly at the water level in case of 8 boxes.
     
  4. daiquiri
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    daiquiri Engineering and Design

    How many Naval Architects do we have now working on this case? :p ;)
     
  5. TANSL
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    TANSL Senior Member

    sharpii2, maybe you're forgetting that some ships can submerge er decks underwater and are not submarines or floating docks, which are either submarines, or platforms that are used to build large concrete blocks, which nor are submarines. These are just some of the cases, thinking half a minute, come to mind.
    Daiquiri, here are many amatuers trying to solve a problem that has no solution and some NA saying that the problem has no solution.
    Cheers.
     
  6. Rastapop
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    Rastapop Naval Architect

    Who are the NAs saying there isn't a solution?
    I see none.
     
  7. Grey Ghost
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    Grey Ghost Senior Member

    You'd have to make assumptions about how the "barge ship" is built. To have enough weight on deck that it pushes a barge underwater, you would want something to keep the buoyancy from turning it over when any reasonable external force happens - rough sea, small load shift, or a forklift to remove the cargo. The drawing doesn't show any ballast or weight in the bottom of the barge.
     
  8. daiquiri
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    daiquiri Engineering and Design

    Good point. The description of the problem doesn't say where is the initial CoG of the ship.
     
  9. TANSL
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    TANSL Senior Member

    Because you do not know how to look, you look with little faith.
     
  10. Nick_Sinev
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    Nick_Sinev Junior Member

    If I were a tutor in a college, I would state this problem in a much more interesting way :)))

    We have a long beam (the length is much greater then the other dimensions) with a square cross section ( rectangular parallelepiped / cuboid). The beam is made of timber, the density is uniform and is 1/3 of the water density.

    In what position would this beam float?
     
  11. Rastapop
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    Rastapop Naval Architect

    Then please enlighten us.

    Ad Hoc is an NA, and he says there's a solution.
    cmckesson is an NA and he says there's a solution.

    I see no other NAs here, do you? Which ones say there is no solution?
     
  12. philSweet
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    philSweet Senior Member

    expanding on Nick's idea a bit -

    1. Let the relative density of any long square section beam vary from 0 to 1. How does it float (orientation) as a function of density.

    2. Generalize to any regular polyhedral prism of n sides.
     
  13. daiquiri
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    daiquiri Engineering and Design

    In the same position in which a much shorter beam would. ;)
     
  14. Nick_Sinev
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    Nick_Sinev Junior Member

    Well, it's a more complicated question. One needs to calculate, what is the minimum length that doesn't affect the behaviour of the beam.

    A floating cube with 1/3 water density seems to be very interesting :)))
     

  15. TANSL
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    TANSL Senior Member

    I hope you do not get mad if I do not answer you. I said what I had to say, read my previous posts. Nothing more than I colud say will cast more light on this issue. To learn you have to go to college and / or work hard.
    Anyway, what I wanted was to continue the joke on the NAs, had begun my friend and respected Daiquiri.
    Cheers.
     
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