South Korean ferry MV Sewol flips, 1/2 sunk in shallows, people trapped.....

Discussion in 'Stability' started by Squidly-Diddly, Apr 17, 2014.

  1. morkisthatu
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    morkisthatu Junior Member

    This is a news story, not facts, which all of us should understand. This is food for thought, but I will wait for the facts to come out after the investigation. There seems to be a tremendous variation in cargo data and I have a few thoughts on that. I have no knowledge of the marine shipping industry so I make assumptions:
    1) Cargo- manufacturers/suppliers place goods into containers and send to customers. I assume they pay shipping costs based upon weight. It would be in their best interest to understate weight. I assume they do.
    2) Union Transport Company are the stevedores who run the docks and load the ships. I assume they bill for their services based upon cargo weight. It would be in their best interest to overstate weight. I assume they do.
    3) Cheonghaejin Marine Company is the owner of the SEWOL. They haul cargo and charge the shipper based upon weight. It is in their best interest to overstate cargo weight. I assume they do.
    4) SEWOL manifest should list the cargo and weight. Why it would be significantly less confuses me. Perhaps there is a tax or dock fee. If so, it would be in their best interest to understate the cargo weight and I assume they do.

    I think there will be a maze of confusion regarding actual cargo weights and applicable billing fraud. What was sent, what was loaded, and what was hauled will all differ.

    One article I read said: following modifications SEWOL has made 197 round trips (394 voyages) between Incheon and JeJu since March 2013, 246 overloaded-1 underloaded-147 no record of load. How can there be "no record"?
     
  2. jehardiman
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    jehardiman Senior Member

    Probably for the inverse of same reason you gave above, no body was getting paid based on CARGO weight. The ship logs will have a rough idea of how much weight is aboard due to drafts and comps; but if no freight, then it is only auto/truck and passanger load...no external lading/consignment document held by a broker/stevedore, no record.

    I wonder who did the pre-departure stability curve and trims; Master, Mate (usual person), or a company officier? And what stability book they were using?...

    I guess it will all out in the end, and somebody will hang, but again this is a human problem, not a naval architecture or ship survivabilty one.
     
  3. morkisthatu
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    morkisthatu Junior Member

    Are you saying a container of lead ingots would be loaded and shipped for the same cost as a container of feathered boas?
     
  4. morkisthatu
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    morkisthatu Junior Member

    Sorry, I read through this again and understand that some voyages may have been without general cargo. It makes sense actually. Return voyages from a vacation spot like JeJu may have been only passengers. vehicles, and empty containers being returned to Incheon. I'm slow, but I got it.
     
  5. CliffordK
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    CliffordK Junior Member

    They may also fudge logs if they are taxed based on cargo, ship capacity, or believe they could be subject to law enforcement sanctions for overloading the ship.

    A log truck driver may overload his truck if he thinks the truck will never get weighed, but will charge the mill for the number of board feet he carried (a different measurement).

    A shipping container will have a maximum rated weight, and an actual weight which may not be the same.

    Based on water displacement of the loaded ship and balast being carried, it should be relatively easy to determine the weight of the whole load.

    I think I read somewhere that divers have already counted the number of cars and trucks physically on the sunken Sewol. Preparations are being made to raise the Sewol, at which time the cargo will be closely scrutinized, although it may be difficult to calculate the previous dry weight of a bunch of waterlogged items. But by that time, it may be old news.

    The notes I'm seeing indicate that the ship was rated for 987 tons of cargo, but was actually carring about 3,600 tons of cargo including 45 containers on the front decks, and 60 on the lower decks.

    It doesn't list the weight distribution of the shipping containers. I'm sure the front upper deck is much easier to load, but also far more damaging to the overall weight distribution of the ship.
     
  6. CliffordK
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    CliffordK Junior Member

    I saw a video suggesting floor drains in RoRo decks dropping into longitudinal below deck compartments. It would seem to me that it would stabilize the ship if water entered uniformly, but destabilize the ship if the water entered predominantly from one side.

    However, what about cross compartmentalization?

    Send the water from the port side of the RoRo deck to a tank/compartment on the starboard side of the ship, and send water from the starboard to a port side tank.

    Obviously add valves, so if the scuppers are above sea level, most of the water would just go out the scuppers unless one consciously desired to fill the tanks (probably use some computer control defaults to detect emergency conditions with manual overrides)

    I'm not sure about the angles based on height, width, and draft, but it should be able to automatically rebalance the ship up to quite a bit of listing, especially as the ship begins to sit lower in the water.

    One might end up allowing more water to enter lower compartments of the ship which could be damaging overall to the probability of sinking if the primary cause of water ingress can't be remedied, but it should help the ship remain vertical as it settles into the water, preventing the very dangerous listing and rollover conditions. If water ingress is exacerbated by listing, then it may in fact help slow the flooding of the ship.

    A ship like the Costa Concordia would be more complex, but as the water rises on one side, it would still be beneficial to get it moved to the opposite side. But, I'm still a bit puzzled by why the Costa couldn't stop the flooding of the starboard side through a gash on the port side.

    The other thing is that I would expect the ships to be able to divert 100% of their motive power into the bilge pumps. So, the Sewol with 15,000 HP engines should have been designed to shunt up to 15,000 HP into the bilge pumps, or ballast transfer pumps. Would we get too many captains over-compensating like the Cougar Ace?
     

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  7. jehardiman
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    jehardiman Senior Member

    Actually, that is true. As far as ISO shipping containers go, they have a max weight limit based on container size, but every container size has a port-to-port alongside terminal offered flat rate (save for minor line margin costs...i.e. a Maersk container will go cheaper on a Maersk bottom than on a APL bottom). Now customs, excise, and port fees are a different matter, but mainline container shipping is all about stows.

    That may not apply to container shipped as deck cargo as opposed to dedicated container stows. From the looks of the original pictures, a lot of that cargo on Sewol was not containerized...way too much flotsam in the water.
     
  8. Pascal Warin
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    Pascal Warin Junior Member

    SOLAS Vessels must have KGmax after damage on board.
    But to answer your question, we need to know content of korean national voyage regulation.
     
  9. ImaginaryNumber
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    ImaginaryNumber Imaginary Member

    South Korea cracking down on operator in Sewol ferry disaster; CEO arrested | CNN
     
  10. CliffordK
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    CliffordK Junior Member

    So, the number of arrests is up to 20? More? Remind me never to draw the wrath of the South Koreans. If they start shutting down ferry lines, then the ones to loose will be the inhabitants of all the small islands that were previously served by the ferries. Will they make the situation worse by sending out smaller ships? Perhaps they will separate the ferry service from the heavy freight service.

    Have they inspected the port side of the Sewol yet? There still is little explanation of what flooded the ship. When the freight shifted, did it knock a hole in the port side of the Sewol superstructure? Did this hole also create a hole in the lower hull and flood one of the watertight compartments? Did it knock a hole in the deck plating? Reports indicate the main generator also shut down. Why? Did that affect the bilge pumps?

    My theory is that the Sewol was running with no ballast, or very little ballast. It may have still been stable after the initial turn (it didn't roll in the first few minutes). However, to correct the listing, the crew filled the Starboard ballast tank with 1000 tons of water, which in turn lowered the ship to the point where the port side flooded.
     
  11. morkisthatu
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    morkisthatu Junior Member

    The incident occurred almost 12 hours into a 14 hour trip of 250 miles. They must have made a great many course adjustments in the first 12 hours, without any issues I've read of. Hard to imagine no ballast.
     
  12. CliffordK
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    CliffordK Junior Member

    The government is still trying to get an accurate estimate of the cargo. I would think the cranes loading the ship would be able to tally the weight of the containers. But they are trying to figure out what was acutally shiped (which will also be needed for insurance or loss claims). Somewhere they have found records of the Sewol being repeatedly overloaded carrying as much as 3,000 Tons of cargo in the past, so the 3,608 T value is not unbelievable.

    The ship was rated at 3,794 DWT.
    Max Cargo: 987 Tons
    Recommended Ballast: 2030 Tons.

    The cargo estimates I've read are 3,608 Tons of cargo (2621 tons overloaded). These may be the highest possible estimates, and may be revised somewhat lower, but notes indicate that there have been at least 30 more cars found on the seabed than were on the official cargo manifest.

    It likely left port with enough fuel to go to the island, and make the return trip (of which some would have been used during the southern voyage), but nonetheless adding to the weight on the ship.

    There was supposed to be an inspection of the "load line" before leaving port.

    The numbers just don't add up to be carrying a singificant amount of water ballast assuming the load line was marked at the 3,794 T mark. The fuel carried would have provided some ballast, but would also decrease during the voyage.
     
  13. powerabout
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    powerabout Senior Member

    ok give us price breakdown, choose a vessel and show us the class charges for the build followed by 4 annuals then a 5 year
     
  14. morkisthatu
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    morkisthatu Junior Member

    Thanks, I'm beginning to understand. With such a heavy cargo load there was no room for ballast weight or they would have exceeded the 3794 "load line". Do ships automatically replace used fuel weight with ballast water to stay in balance during a voyage? Now it's clearer how the ship became "tippy".
     

  15. ImaginaryNumber
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    ImaginaryNumber Imaginary Member

    Pulling up the Sewol could take six months and cost US$98,240,000
     
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