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

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

  1. Squidly-Diddly
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    Squidly-Diddly Senior Member

    http://www.sfgate.com/news/world/ar...Korea-ferry-sinking-5405747.php#photo-6172548

    Captain seems to be taking responsibility.

    Boat said to have been making turn too fast.

    I'm thinking "Wouldn't a passenger ferry be designed so it wouldn't tip over no matter what the helmsman and passengers were doing? Like even if making its most extreme turn and all the passengers run to one side to look at something?"


    SOUTH KOREA OUT - BEST QUALITY AVAILABLE An undated file picture made available on 16 April 2014 shows the Sewol vessel at sea, South Korea. The ferry, with 470 people on board on 16 April 2014, was reported sinking off the south-western coast of South Korea while en route from the port of Incheon, west of Seoul, to Jeju Island. The passengers were mostly secondary school students on a field trip to Jeju island. The Coast Guard dispatched patrol boats and aircraft for rescue operations are under way.



    PIC OF BOAT BEFORE SINKING
    Read more: http://www.nydailynews.com/news/wor...engers-aboard-article-1.1757694#ixzz2z9Dq0TYu


    PS-now (as per standard Third World practice) the captain was among the very first to abandon ship.
     
    Last edited: Apr 19, 2014
  2. Manie B
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    Manie B Senior Member

    Looking at this photo wasn't this bad design = top heavy ????

    Just my 2 cents ????
    Accident waiting to happen ???
     

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  3. IEWinkle
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    IEWinkle Retired Naval Architect

    A Possible Cause?

    It would seem that the vessel may have suffered raking damage underwater similar to that sustained by Costa Concordia. If this was the case it is likely to have opened up a number of empty wing compartments on the port side up to 4.5 m wide by about 8.0m deep. These should be cross-connected to the starboard spaces, but if sufficient inflow occurred to more than 2 of these spaces it is possible that the vessel's list would become larger than that which would allow the cross-connections to function, effectively holding the vessel down on its port side, an effect compounded by cargo movement on the vehicle deck. The lack of trim in the later photos suggests that such damage would probably have been around the mid section of the vessel where these compartments would have the largest volume. Although the vessel seems to have stabilised with a large list, progressive flooding within the superstructure would have gradually increased the list until capsize.

    Such a scenario may be unique in the Ro-Ro world and might suggest the need for a review of the practice of using large void wing tanks in such vessels (there are several examples of large Ro-Pax vessels where these spaces are filled with empty plastic drums to reduce permeability).

    I have just seen photographic evidence that this vessel has also had an extra deck added to the aft end of the superstructure aft of the funnel within the last two years (when she transferred from Japanese ownership) which would have compromised her stability to some extent as there were no compensating blisters added.

    Much will no doubt be said about the apparent lack of crew comprehension of the critical state the vessel was in and the lack of any organised evacuation of passengers who had been told to stay where they were inside the vessel - a probable death sentence in a vessel listing to more than 45 degrees! This is further reinforced by the fact that only two of the many life rafts were released for use just before the capsize from their storage racks to port and starboard just behind the bridge. There do not appear to have been any other form of lifesaving appliances on board other than life jackets!
     

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    Last edited: Apr 17, 2014
  4. Sailor Alan
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    Sailor Alan Senior Member

    Ferry Stability

    Thank you IEWinkle, interesting analysis.

    Thank you Manie B for the photo. The chine line on this vessel seems interesting, with a rather short section of relatively ‘square’ hull cross section, and a long ‘run’ aft, presumably to the propellers etc. I am learning hull design on Rhino, and some of the exercises show hull shapes very similar to this. Does this mean this hull shape is fairly common?

    IEWinkle, if superstructure was added aft, and there seems far less deep, or ‘hard’ chine area aft than i would expect, does this imply poor judgement with the modification, or just a restriction in operating wave height/wind speed?

    Suffering raking damage implies hitting something, a rock, or could a container do this kind of damage?

    Hitting a rock implies being off course, which happens, even if it is inexcusable these days.

    I heard navy divers were swept away from the site too, must be rough tidal or weather conditions there.
    The photos all seem to show virtually no rafts having been launched at all. Certainly manny seem to have died as a result of poor instructions.
     
  5. IEWinkle
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    IEWinkle Retired Naval Architect

    Some additional analysis and thoughts

    Further to my Post 3 above, I have managed to estimate the effect of flooding from 5 to 15 % of the vessel's displacement (about 520 to 1550 tonnes) in its port wing tanks. Despite considering initial GM values from 0.15m (IMO minimum) to 2.0m I can only obtain angles of list up to 28 degrees (with the largest flooding value and lowest GM) and about 10 degrees for the lowest flooding and largest GM. This is not sufficient to flood the superstructure above the vehicle spaces which should have been watertight at least to 14m depth (about 35 degrees).

    At angles of 25 degrees plus there will be added contributions from some movement of cargo but in calm conditions this will not become significant until about 35 degrees or more depending on cargo type. In order to get the larger list clearly indicated in the the many photographs it is necessary to consider flooding of the vehicle deck, but there seems to be no obvious entry point other than the possibility of faulty scuppers which should have non-return valves fitted. If these were jammed open, then progressive flooding of the vehicle space could take place which would provide a slow mechanism to achieve angles of 45 degrees or so within about half an hour to an hour. This would require about 1000-1500 tonne of water on the vehicle deck as well as the flooded wing tanks below. Shortly after this the superstructure decks reach the water level and will start to accelerate the capsize as water enters through open doors etc. It is clear from the immediate pre-capsize photos and video when the vessel is at about 85 degrees that more than half the vessel is out of the water indicating that she still had a great deal of further flooding to take place before she could roll right over and sink. In the final capsize video sequences there are clearly visible openings venting air which would appear to be from some of the vehicle deck scuppers as water flooded in.
     
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  6. rwatson
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    rwatson Senior Member

    Interesting observations IW. Thabnks for the posts.

    The other day, they had a marine architect being interviewed on TV about the accident, and he stated that as little as a foot of water on the lower vessel deck could compromise stability badly for this design.

    I have no way of knowing if this was true, but it will be interesting to see the analysis unfold over the coming weeks.

    One report I saw
    "Also, the captain was on a vacation so the one who was driving the ship was a temp, they altered from the original route to make up time they lost for the fog delay."

    The human factor looks like it may have been a big part. Speculation of course.

    I feel very bad for the poor passengers.
     
  7. rwatson
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    rwatson Senior Member

    I saw the photos of him being recused early.

    But, I did think - what the heck could he do about it ?

    He didn't have a craft he could command, he had no chance of doing anything with his ship as it was totally out of control, there were hundreds of boats on site trying to get to people already.

    Going down wit the ship is noble if there is a shortage of lifeboats, or you are trying to manoeuvre the ship to assist passenger rescue right up to the last moment, but when its upside down, and your bridge is twenty feet underwater - WITFP ?

    It would be like the driver of a car in a crash - with the police, ambulance, firetrucks etc - what on earth was he qualified to do for any injured passengers ?
     
  8. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I think it is pretty standard in 1st world that the captain would be the most qualified to direct crew to evac passengers and even to direct any outside rescuers as to where trapped passengers might be, and to any particulars of the vessel and incident.

    Plus, the captain should be able to 'handle himself' much better than hapless passengers, so he should be able to hang out to the last moments.

    He should be able to be doing stuff like deploying life rafts, even if he can't see passengers, in hopes anyone in the water will make it to them, etc.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    South Korea isn't Third World, you would expect better than this, someone was negligent in putting a rookie at the wheel, or not adequately supervising her.
     
  10. powerabout
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    powerabout Senior Member

    I thought the only safe design for a ferry is a cat?
    Monos's keep proving they are killers
     
  11. nettersheim
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    nettersheim Consultant

    Ferries are basically wrong designs...
    Un-subdivided deck just few meters above summer draught level...

    Even with most stringents rules (deterministic "Solas 90" or probabilistic "Solas 2009") ferries are unsafe.

    European Union decided after "Estonia" disaster (1994) to increase the Solas requirements for ferries trading in european waters : on top of Solas chap. II-1 designers have to consider some water on the main ro-ro deck (so called "Stockholm agreement").

    European ferries are therefore "Solas 90 + Stockholm agreement" designs or even "Solas 90 + Stockholm agreement" + "Solas 2009" for the most recent ones.
     
  12. IEWinkle
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    IEWinkle Retired Naval Architect

    Cats vvs Monos

    The only problem is that cats can't carry the same amount of cargo which pays the bills for most of this type of ship. The nearest comparison in Europe with the type of vessel represented by SEWOL is the overnight North Sea ferries running from Hull and Tyneside to the near continent. They may be somewhat bigger, but the nature of their cargo/passenger mix does not seem that different - cats could not carry the cargo efficiently!
     
  13. Rastapop
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    Rastapop Naval Architect

    I think his biggest fault is probably not recognising that he should have told the passengers to evacuate.

    From what the survivors say it pretty much sounds like the people who ignored the crew instructions lived, and the ones who listened died.
     
  14. rwatson
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    rwatson Senior Member

    Its always easy to criticize someone thousands of miles away from reports by third parties.

    The inquiry may reveal many mistakes - but I have pondered his situation where he could have forced hundreds of small children into the freezing, fast flowing water.

    Then we could have a debate about how he caused hundreds of deaths by ordering drowning and exposure.

    Its a common human reaction to want to find a 'scapegoat' to direct their anger on, but like all accidents, its a always a case of a cascading series of events that culminate in the incident.
     

  15. morkisthatu
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    morkisthatu Junior Member

    The sudden turn of the Sewol seems to be the first sign of trouble. I've seen conflicting reports on which way they turned. It seems they were on course and no threat of reefs in the area. Could there have been a sudden failure of an engine/drive shaft/propeller which caused the sudden turn? Perhaps exaggerated by strong current and waves? Approximately ten minutes after the sharp turn the ship was reporting capsizing and then came the "bang". Likely cargo, but could it also have been the propulsion system?
     
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