Naked Science Forum
Non Life Sciences => Technology => Topic started by: CliffordK on 04/05/2014 10:24:37
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On both the Sewol and the Consta Concordia, the captain/crew ordered the passengers to their cabins shortly before the ships capsized.
In these cases, the more logical order would have been to don the life jackets, then head to the lifeboat decks to await further instruction. There may in fact be some benefit of sending 500 passengers (say 500x100 lbs = 25 tons) to the high side, although life boats should be launched from both sides of the ship.
If the ship was in fact able to recover, one just chalks it down as a "drill". Obviously getting 500 kids crammed against the railing, someone might fall overboard. Would they just start jumping before the abandon ship order?
Anyway, so the question is how frequently are there "false negatives"? Times in which the proper action would be just to wait and see if the ship will recover.
The MV Cougar Ace [img float=right]https://upload.wikimedia.org/wikipedia/commons/thumb/b/b6/Cougar_Ace_on_side_%28starboard_side%29.jpg/320px-Cougar_Ace_on_side_%28starboard_side%29.jpg[/img] (https://en.wikipedia.org/wiki/MV_Cougar_Ace) was a cargo ship that developed a severe list, but ended up not sinking, and eventually was salvaged and repaired.
Recently, there were also one or two cruise ships that had significant fire damage, but managed to stay afloat.
However, at least the passenger ships that hit the news that developed a mild list eventually capsized. In some cases, Ro-Ro Ferries have capsized in a matter of minutes, whereas the Sewol took about an hour between the time where a critical danger was discovered and the tilting ship made egress difficult.
So, is "go to your quarters and await further instruction" ever appropriate?
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I think I would ignore the order and get as close to a lifeboat as I could
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There is an extra risk with Ro-Ro ferries in that there are doors which are not completely sealed going much further down the hull than on other ships, and that means that once they've tipped far enough for parts of these doors to be under the surface, it's unlikely that sinking can be prevented. They are inherently dangerous designs of ship and should really be done away with. Whenever I've travelled on them, I've always taken a good look around to see where the liferafts are and I've either stayed on deck throughout the trip or just inside if the weather's bad. On a long ferry trip I'd rather do without a night of sleep than go down into a cabin.
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I was looking at the Sewol information again today. None of the cabins were down near the waterline, but were restricted to the top 3 decks.
However, the top (open air) deck appears to be wide open, and could have easily handled all of the 500 passengers, and is also where the life rafts seem to have been located (of which 1 out of 46 were deployed).
The passenger cabins apparently had non-opening windows, and no balconies, although all of the decks with people had some open air areas.
I think David's comment is good. While one might not shun the cabins while the ship is sailing, as soon as an emergency occurred, all passengers should have been urged to quickly head to the top lifeboat deck. If the ship had been saved, they would have just had to contend with a few chilled kids.
Once the ships hits about 45°, it becomes very difficult to climb, and one might easily get stuck in the cabins. At 90°, cabins would be very difficult to get out of without a rope, and the only way out may be an underwater plunge through icy water. But, even that may be difficult as water would be flowing into the ship, so escape would be swimming against the current. Thus... one would need ropes and ladders to climb. I do, however, believe the ships still need an evacuation plan for high angles of listing.
It may have been appropriate to wait on ordering the evacuation of the ship until rescue's imminent arrival, but "stay put" should have meant at their life raft muster stations. Fortunately, by the time of the abandon ship order, the life rafts were essentially sitting at water level. still only one was deployed.