Container ship "flexing" in heavy seas. Awesome sight below deck.

Discussion in 'All Things Boats & Boating' started by djaus, Feb 20, 2014.

  1. djaus
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    djaus Salted Nut!

  2. rwatson
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    rwatson Senior Member

  3. jehardiman
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    jehardiman Senior Member

    Meehh, typical, and why ships are built of steel. Hogging or sagging a foot or two is common. On ore carriers you can actually see the hull girder troque in a cross seaway. This is why catwalks have expansion joints and transfer pipes on supertanker decks have relief bends.

    Normal flexure of a structure has nothing to do with failure, as a ship will flex in a seaway. The failure occurs not because of the flexure, but because of design, fabrication, or material issues.
     
  4. djaus
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    djaus Salted Nut!

    Well I'd never seen it happen before. Bet I'm not the only one too. Some of the comments under that YouTube vid mention how first time viewers react.
     
  5. djaus
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    djaus Salted Nut!

  6. Ike
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    Ike Senior Member

    Most large cargo are designed lightly, and the cargo, especially in bulk carriers is part of the structural strength of the hull. That is they are stronger loaded than when they are unloaded.
     
  7. TANSL
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    TANSL Senior Member

    Here's a concept that can be misleading, or perhaps I misunderstood. A structure, when fully charged, acquires a deformation which, until discharged, it is difficult to remove. But that does not mean that the structure is stronger: the structure is the same, just as strong as before, but distort it a bit more, it's hard.
    Regarding the video, without having quantified the problem (deformation), it appears that the structure is too deformed. If I were the owner, I'd be worried about my boat.
     
  8. Ike
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    Ike Senior Member

    I used a poor choice of words to state what is a complicated subject. But the point is, the load is considered in the design as adding to the structural integrity of the ship.
     
  9. TeddyDiver
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    TeddyDiver Gollywobbler

    Like Saturn V fuel tanks..
     
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  10. rxcomposite
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    rxcomposite Senior Member

    All ships are limber for two good reasons. Economics and design requirements.

    It is designed with a minimum amount of material while keeping within the safety standards. It is designed to flex to absorb the shock of the waves.

    This flexing design principle is not limited to ships. Bridges flex, so does airplane wings. The bridge flex to sway with the wind. It is built with the minimum of structure so as not to present a large cross sectional area to the wind. The airplane, when taking off, its wings flex downward reducing drag and adding to ground effect. In flight, the wings flex upward, adding stability.
     

  11. djaus
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    djaus Salted Nut!

    Build anything 400ft long & it's going to flex. Cool video ha' !
     
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