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

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

  1. Rastapop
    Joined: Mar 2014
    Posts: 278
    Likes: 5, Points: 18, Legacy Rep: 46
    Location: Australia

    Rastapop Naval Architect

    This is misleading.

    A builder builds what he's told to build.

    Class societies do include provisions for vessels to last (for example extra hull thickness to allow for losses over the life of the vessel).
     
  2. powerabout
    Joined: Nov 2007
    Posts: 2,931
    Likes: 66, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    Nice dream but its not reality
     
  3. Rastapop
    Joined: Mar 2014
    Posts: 278
    Likes: 5, Points: 18, Legacy Rep: 46
    Location: Australia

    Rastapop Naval Architect

    Care to elaborate?
     
  4. powerabout
    Joined: Nov 2007
    Posts: 2,931
    Likes: 66, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    here's a starter pack to how class works and the results there of;
    www.c4tx.org/ctx/pub/tromedy2.pdf‎

    Investment bankers that dictate how the industry runs now ensure they get vessels that they can scrap in 5 - 10 years and having worked on both of these types I can tell you your most important crew member is the welder just trying to get it to its design life.
    Mention the work 'class' to a decent Mega Yacht builder and they say sorry we dont build down to class
     
  5. Rastapop
    Joined: Mar 2014
    Posts: 278
    Likes: 5, Points: 18, Legacy Rep: 46
    Location: Australia

    Rastapop Naval Architect

    Who do you think own the shipping firms, and want the ships to last their intended 20-25 years?

    You're a fully paid up member of the tin foil hat brigade.
     
  6. powerabout
    Joined: Nov 2007
    Posts: 2,931
    Likes: 66, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    In 1970 I'll bet that was true but not today.
    I think you will find the finance companies have a bit of say.
    Do you work in this industry?
     
  7. Sailor Alan
    Joined: Mar 2014
    Posts: 299
    Likes: 15, Points: 18, Legacy Rep: 85
    Location: Gig Harbor WA

    Sailor Alan Senior Member

    Seawol, Bolger, and Tredwin

    Speaking of stability. Has anyone noticed the startling similarity between the hull shapes of the Korean Ferry Seawol, Bolger’s Romp, and the barge yacht designs of Tredwin, Griffith's et-al. Is this 'real', an illusion, or does the 'rules' of fluid dynamics force this solution.
     
  8. JosephT
    Joined: Jun 2009
    Posts: 859
    Likes: 107, Points: 43, Legacy Rep: 218
    Location: Roaring Forties

    JosephT Senior Member

  9. Sailor Alan
    Joined: Mar 2014
    Posts: 299
    Likes: 15, Points: 18, Legacy Rep: 85
    Location: Gig Harbor WA

    Sailor Alan Senior Member

    I for one find this extremely suspicious. Do i understand IEW correctly, that ships, like airplanes, ‘feel’ completely stable until they actually roll over? Presumably this is another captain excusing himself from testimony on behalf of either the company or the jailed captain.

    With an airplanes stability speed is a factor, ie with a too far aft CG, the plane ‘feels’ stable until you slow down, whereupon it might just fall out of the sky unless you are pretty slippy with the throttle, or you have room to put your nose down for speed.
    Note; really hot shot P-51 Mustang pilots used to fly with their rear auxiliary tank partially full, completely against regulations, so the plane would be dynamically neutral, nearly unstable. It would flick into a roll faster than anything else in the air. Unfortunately, the slightest sign of icing, at 30,000ft no less, and it was an unrecoverable spin. Some reports had it more Mustang pilots were in German POW camps from this than from enemy action?

    Sorry about the rabbit trail.
     
  10. powerabout
    Joined: Nov 2007
    Posts: 2,931
    Likes: 66, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    Many ships are more stable when they are upside down....lol
    Did you read the carnival cruise ship issue, some big rudder movements got 28 degree heal.
    31 degree was max stability. Sounds like a helmsman could actually roll one over maybe?
     
  11. ImaginaryNumber
    Joined: May 2009
    Posts: 435
    Likes: 59, Points: 28, Legacy Rep: 399
    Location: USA

    ImaginaryNumber Imaginary Member

    South Korea Ferry Was Routinely Overloaded | New York Times
     
  12. sharpii2
    Joined: May 2004
    Posts: 2,138
    Likes: 261, Points: 83, Legacy Rep: 611
    Location: Michigan, USA

    sharpii2 Senior Member

    Now this explanation has a real ring of truth about it.

    Cargo substituted for ballast. Got away with it through careful helmsmanship and a careful eye on the weather.

    Then bam! The steering gear fails.

    The poor ship plainly ran out of luck.
     
  13. CliffordK
    Joined: Feb 2012
    Posts: 24
    Likes: 2, Points: 0, Legacy Rep: 20
    Location: Oregon, USA

    CliffordK Junior Member

    Ballast, of course must be kept low.

    Does anybody know how low the vehicle deck was?

    Ahh, found some layouts from the clip:
    http://www.youtube.com/watch?v=ALZFk1a0Q2Y

    So, the Ro-Ro cargo deck is low, but appears to be just above the water level (when the ship is on an even keel, probably below water level when listing). Substituting cargo on the lower deck for ballast raises the center of gravity slightly. Adding more cargo on the foredeck is much worse. And, of course leaving it unsecured at open sea is ill advised.

    Not draining the ballast tanks reduces the freeboard, and increases the likelihood of water ingress. Draining the ballast tanks reduces the ability to pump water to where it is needed, and further compromises the ship's stability. The ship should have had quite a bit of freeboard, but apparently let water in through either the rear cargo hatch, or through poorly designed/maintained scuppers.

    Anyway, I'm surprised there isn't better monitoring of the loading of passenger ships.

    As far as when the Captain left the ship, it was listing to the point where the upper deck was nearly in the water. Five minutes later and he would have been wading. Being an elderly man, and not an acrobat, he likely couldn't do much more onboard at that time. Did they have ropes and safety harnesses? Still, with his extreme lack of good judgement, they likely were better off with him off of the ship.

    Shipping doesn't go with "FIFO"... Fist in - First off?

    One could argue whether it was a good call to wait until help arrived before ordering to abandon ship.

    The very poor judgement was to not immediately call everyone to the "muster stations" on the upper lifeboat deck at the first sign of trouble. The Sewol took over an hour to roll 90°. Some Ro-Ro ships haven't been so lucky.

    As far as survival rate, as far as I can tell, 100% of the crew who were stationed on the upper deck survived. About 60% of the crew on lower decks survived, and less than half of the passengers on the lower decks survived.

    I would have probably initially wished for the passengers to be on the "high side" for balance, but once the ship hit about a 40° angle, and rescue was imminent, they should have been moved to the lower side of the upper deck along the railing and life boats.

    There is no reason to not have just about every life boat deployed in the water.
     

    Attached Files:

  14. Pascal Warin
    Joined: Feb 2012
    Posts: 81
    Likes: 2, Points: 8, Legacy Rep: 38
    Location: Paris

    Pascal Warin Junior Member

    You will be depressed to learn that you know absolutely nothing about class industry and should rather shut up.
    The big money comes with survey during vessel life.
    Of course class societies want to have new ships in their fleet to prepare future income.
     

  15. Pascal Warin
    Joined: Feb 2012
    Posts: 81
    Likes: 2, Points: 8, Legacy Rep: 38
    Location: Paris

    Pascal Warin Junior Member

    It is mandatory that this deck be above water in every intact condition regardless of trim as it is actual freeboard deck.
    A SOLAS vessel should even have positive freeboard of 76mm in damaged condition too. Regarding national rules ... who knows ?

    For all that, "above" does not mean "high above" as cargo door is supposed to be watertight.

    As soon as flooding of Ro-Ro space starts you can consider the ship as potential total loss.
    But that is a rather slow process unless you looses the door ("Estonia") or have it open ("Herald of free entreprise").

    Here the big issue was clearly not calling passengers to muster station asap. It turned an accident to a disaster.
     
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.