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

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

  1. IEWinkle
    Joined: Jan 2012
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    IEWinkle Retired Naval Architect

    Inevitability of Capsize!

    To my knowledge there are no other Ro-Pax accidents that appear to have generated lists of 45 degrees or more from cargo shift alone. One example of slow progressive flooding that I can recall, is the case of the WAHINI (in a storm) which also grounded. The only other example of slow progressive flooding (in a force 12 storm) leading to capsize without hull damage is the ill fated PRINCESS VICTORIA, 61 years ago, which was unable to successfully evacuate its passengers (despite many heroic attempts) due to the excessive sea state. Slow capsize is associated with slow progressive flooding without any compensating down-flooding to cross-connected lower wing tank spaces. An example of a ship which survived a major collision (holed above and below the vehicle deck) is the MV HAMBURG in the Elbe estuary which teetered at 35 degrees before slowly recovering through crew action to establish down-flooding of the floodwater on the vehicle deck to the cross-connected lower wing tank spaces (I have personally interviewed the Master of that vessel in transit after its repair and reinstatement). The less fortunate EUROPEAN GATEWAY, after similar damage both above and below the vehicle deck, grounded on a sandbank and reached about 40 degrees in 20 minutes and then rapidly rolled on her side. I am not aware of a single Ro-Pax vessel that has ever survived a list of more than 35 degrees.

    SEWOL now appears to have suffered only an initial cargo shift which led to a substantial heel angle (probably 20-30 degrees initially). To get to 45 degrees requires progressive flooding from some source(s) (yet to be determined) and unless this is halted or compensated by down-flooding to the cross-connected lower spaces, capsize is guaranteed. A competent crew would have checked all major spaces for flooding and drawn the logical conclusion that there would be no recovery without some means of stopping or reducing that flooding. It is a major lack of understanding of the fundamental nature of their vessel and its inherent stability weakness (common in many Ro-Pax crews) that has lead to a complacent approach to passenger evacuation which has proved so fatal in this case. Marshalling of the passengers on the side or top decks should have commenced as soon as the list started to increase once the vessel was dead in the water. Leaving any passengers inside once the list started to increase is to my mind completely culpable. Evacuation into life-rafts should have proceeded as soon as possible thereafter given the relatively calm conditions. Unfortunately this vessel (and its sister) do not appear to have had any small powered vessel to port and starboard which would normally have been lowered to marshal the liferafts.
     
    Last edited: Apr 27, 2014
  2. morkisthatu
    Joined: Apr 2014
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    Location: Ft Myers, FL USA

    morkisthatu Junior Member

    Sewol

    The more I read about this disaster I begin to understand the enormous task before the prosecutors and investigators. Everyone seems to have contributed to it in some way.
    1) Crew: conduct; skill; commands.
    2) Ship modifications: design; inspections; revised cargo and passenger capacities; revised balllast reqmts.
    3) Safety: Faulty equipment; lack of training; Korea Shipping Association.
    4) Ship operating systems: ballast; steering; drainage scuppers; electrical; etc.
    5)Cargo: Actual versus design capacity; stowage; balance; Union Transport Co.
    6) Owner: Cheonghaejin Marine Company; multiple topics.
    7) Governance: Korea Register of Shipping; Ministry of Ocean and Fisheries; Korea Shipping Association; ROK Coast Guard.
    8) Conclusions about flooding and capsizing.
    9) Rescue and recovery efforts.

    The sister ship, Ohamana, is reported to have safety issues as well.
     
  3. powerabout
    Joined: Nov 2007
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    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    what you will learn is the shipping industry is re-active not pro-active.
    There are only changes after you kill lots of people and then many of those changes only apply to new buildings
     
  4. IEWinkle
    Joined: Jan 2012
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    IEWinkle Retired Naval Architect

    The more you look the worse it gets!

    Having looked again at the loss of ARIAKE (a very similar design to SEWOL built in the same Japanese yard a year later) which was lost (with all passengers and crew saved) to partial capsize following severe cargo shift (after being hit by a freak wave) and eventual grounding with about 45 degrees list in Nov 2009, a Google search will quickly take you to SUPERFERRY 9 (ex-ARIAKE completed 1986 in Japan) which capsized on 9th Sept 2009 in the Philippines- just a little larger than SEWOL, but with similar stern ramp design but an open upper vehicle deck. In this case she took about 5 hours to capsize after reporting a starboard list. Cargo shift was suspected, but she lies 5000m deep and there has been no investigation of the cause of any flooding. All this occurred only a year after the loss of PRINCESS OF THE STARS (June 21st 2008) which was sent to sea in the Philippines to encounter Typhoon Fengshen which precipitated another example of cargo shift, followed by slow capsize. She was also Japanese, of similar arrangement but significantly larger than SEWOL, built in 1984 and sold on in 2001 to Sulpicio Lines in the Philippines, capsized in about 6 hours with only 48 survivors from 862 passengers and crew despite an early attempt at evacuation. In this case the sea was rough and passengers were having to jump considerable distances into the sea to reach life rafts. Each dead passenger's family was compensated only $4,500. Sulpico Lines were also the owners of the ill-fated Dona Paz - largest loss of life (4341) from any passenger ship in 1987 - and have been involved in 3 other passenger vessel losses since. In addition, Sulpicio, uniquely, is the only passenger carrier that has been dropped from membership in the Protection & Indemnity Club, a cooperative insurance venture that would otherwise have provided adequate coverage.

    All this indicates carelessness, poor maintenance and disorganised evacuation on top of a propensity to vessel capsize. How much of this is repeated in the SEWOL incident remains to be seen.
     
  5. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    plenty in the Korean English papers..Classification society staff past and current have had their passports pulled and office raided
     
  6. morkisthatu
    Joined: Apr 2014
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    Location: Ft Myers, FL USA

    morkisthatu Junior Member

    Damn, this is depressing.
     
  7. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    Then you would be even more depressed to learn that the for profit classification socities that make income from newbuilds have absolutley no interest to make a vessel that will last nor does the shipyard
    How would you like to fly if that was the system...luckily its not.
    You can buy a car andget 5 year warranty
    Spend a billion on a drill ship get 12months...
    Have a guess who is the most important crewman on a modern vessel....
     
  8. Sailor Alan
    Joined: Mar 2014
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    Location: Gig Harbor WA

    Sailor Alan Senior Member

    Rudders and things

    Thank you all, especially IEW for your masterful explanations. I was there for the Wahini disaster, in Wellington, not on the ferry.

    It was ‘surfed’ up on the rocks, and the forward bottom ripped out. Then the wave surge dragged it back into the harbor, where it filled and rolled over. I would not have called it a ‘slow’ rollover, but it wasn't very fast either. I think everybody got off the boat, but there was horrific loss of life getting ashore. A very large number of casualties were from people in life jackets washed against the ragged rocks by that same surf, heartbreaking to watch live survivors in the waves became bodies lodged in the rocks ashore, where i was standing.

    I have heard little more speculation about the rudder. I think there is only one, no photographic evidence of more. Our 737 experienced an un-commanded ‘hard over’ rudder failure, leading to the March 3/91, UA-585 and the Sept 8/94 US-427 crashes. The root cause was contaminated hydraulic oil, no one had changed the hydraulic oil since new, in spite of an AD to do so after a certain number of flight hours. The actual cause of the rudder failing ‘hard over’ was complicated, and relied on a strange combination of leaking seals, and ‘stuck’ valves. The seals were damaged by the contaminants, and no designer could have imagined the weird combination of seal leaks and stuck valves that lead to this failure. A rare case where not enough backups were provided. Please note; this is rarely mentioned in documents pertaining to these incidents.

    Could it be possible that a similar lack of maintenance caused a similar ‘hard over’ failure.

    This still doesn't' explain why the boat rolled so far, and so quickly. I get the added partial aft deck, the shifted cargo, and possibly stuck scuppers, but even given all that, IEW shows it should not still have rolled so far, so fast.

    Please Note; IEW, all ferries that i know of in the PNW are bow and stern load/unload. The Canadian ones and the “Black Ball’ from America have ‘proper’ bows with doors, all the rest are simple two ended hulls/superstructure.
     
  9. powerabout
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    powerabout Senior Member

    Ships like 737 only need a single actuator ( correct me if I'm wrong)
     
  10. ImaginaryNumber
    Joined: May 2009
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    ImaginaryNumber Imaginary Member

    Here’s the exact moment South Korean ferry captain abandoned ship and kids to die | WASHINGTON POST
    [​IMG]
     
  11. Sailor Alan
    Joined: Mar 2014
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    Sailor Alan Senior Member

    Rudder controls

    #Powerabout,

    Im not sure how to answer this. The 737 airplane has a single casing with two concentric actuators inside it. These *were operated by a single dual valve, powered by completely different hydraulics circuits, each from a different main engine. If a hydraulic circuit looses fluid, it usually becomes ‘free’ and simply slides uselessly. If it seizes, it is stuck. This was our answer to the issue of one hydraulic piston being jammed/seized. Under normal operation, both slides worked together. If one slide was stuck, the other made the whole stroke, and the pilot didn't feel any different, nor did he have to make any changes. If both systems failed, or he felt the controls too heavy, he ‘stomped’ on one pedal, and the main power system disengaged. This caused the 3rd system, powered by hydraulic accumulator (i think) to operate the controls, at at least half power, though probably diminishing as the reservoir was used up. New versions of this plane have this circuit powered by the APU. Finally the 4th system came into play, the manual steel cables. These are connected all the time, and in fact the 737 system is technically ‘power boosted’ and not full power controls. Please note, the rudder on a plane, unlike a ship, is not regarded as a necessary control. In fact you can fly the plane, if a little roughly, without a rudder control at all.

    The investigation was very controversial. FAA, Boeing, and Parker-Hannifin (the manufacturer) all inspected all components and could find NO evidence of sticking, no scratches etc. Extensive tests in a physical simulator, real components connected properly, but on the ground, using engineers who had no previous knowledge of the system, showed no faults ever. Someone eventually found that a 180’ difference in inlet oil temperature to system casing temperature might cause some seals to not seal properly, they called it ‘thermal shock’. But as the maximum temperature possible between the components (-40’ ambient) and the highest temperature the oil could get, about 90’, this didn't seem likely either. My thoughts are; and i wasn't very close to this investigation, it was the hydraulic oil like split pea soup probably compounded by the co-pilot ‘stomping’ on the pedal in his effort to pull back on the stick that did it. No pilot should ever ‘stomp’ on a pedal, hence the choice of this method to disengage the original power system. The NTSB and others were very unhappy with this decision, still claiming there is a flaw in Boeings remaining design.

    Regardless, a very good plane, and the early ones at least were a bit of a rocket to fly.

    * all these valves were replaced in all 737’s at Boeing expense with a pair of separate valves, though still in the same body, for mounting/compatibility.
     
  12. Navygate

    Navygate Previous Member

    Sailer Alan,
    Always good input, thank you.
    If I may clarify:
    Canadian west coast ferries (BC Ferries) use bow - stern door vehicle loading while USA Black Ball COHO uses a stern door and a forward-midship side door and has so since 1959 when she was launched.
    Even the semi truck trailers use it.
    Craziest thing I've ever seen.
    Not unlike their spring-line stern-to landing method State side in Port Angeles.
    :)
     
  13. Sailor Alan
    Joined: Mar 2014
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    Location: Gig Harbor WA

    Sailor Alan Senior Member

    Seawol

    Thanks Navygate, i was relying on memory, not a good thing these days. :)
     
  14. Navygate

    Navygate Previous Member

    Oh I don't know, you seem to be doing alright to me.
    :)
     

  15. Corley
    Joined: Oct 2009
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    Location: Melbourne, Australia

    Corley epoxy coated

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