Last voyage for Costa Concordia cruise ship

Discussion in 'All Things Boats & Boating' started by daiquiri, Jan 14, 2012.

  1. Yobarnacle
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    Yobarnacle Senior Member holding true course

    while I agree with your long gash analysis and unsurvivability assesment og both Titanic and Concordia, I beg to differ about riveted hulls built before WWII.
    I have sailed on many riveted ships on the Great Lakes, some built before 1900. Operating in heavy ice! Welding replacing rivets was a labor saving factor. Not an improvement of strength. Rivets need doubler plates over seams. Most of the vessels I've sailed on "threw" rivets pounding into heavey ice. We'd nail a marlin spike in the rivet hole, weld a bead around the inside and carry on. These were strong ships, some lasted more than 100 years. True fresh water was a major contributer to longevity. But the ice is equally hard or harder than salty ice.
     
  2. hoytedow
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    hoytedow Carbon Based Life Form

  3. IEWinkle
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    IEWinkle Retired Naval Architect

    I'm afraid this is incorrect as a rivetted plate is only about 80-85% as strong as a the same welded one simply because of the loss of cross section at the rivet holes. For this reason the scantlings of rivetted vessels are significantly greater than their welded equivalents. Less steel, less resistance and less labour are the major savings in welded construction.

    Your Lakers would all have been built with ice strengthened bows with extra frames and thicker plating in way of the waterline and would happily deal with fresh water ice sheets or broken ice, even though harder than sea ice. The difference in the case of an iceberg (which is also fresh water ice) is its mass and inertia, similar to that of the Titanic itself, in this example with the ability to punch through plating and fracture rivet seams exactly as occurred with the Costa Concordia.
     
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  4. IEWinkle
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    IEWinkle Retired Naval Architect

    But in the case of sea ice the salt remains trapped at the crystal boundaries to produce the equivalent of frozen slush - hence the weakness of sea ice - not to be confused with icebergs which are pure fresh water ice.
     
  5. BPL
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    BPL Senior Member

  6. annex
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    annex New Member

    This article mentions closing off some compartments for shallow water:

    http://travel.usatoday.com/cruises/...osta-Concordia-disaster/52808568/1?csp=34news

    and one I saw a week ago mentioned crew seeing two holes...one long one with a rock in it, and a shorter one...here's what the article had, from a French interview with the chaplain:
    'I saw a few members of the crew who were working in the engine rooms. They told me: "We are all going to die. On the hull we have a 70m-long gash with a rock inside and another about 10m long."'

    Read more: http://www.dailymail.co.uk/news/art...aby-abandoning-cruise-ship.html#ixzz1kcYFlKHA

    I've been following along in the boatdesign forum, finding you after the accident. I have learned so much from you all. Thank you!
     
  7. Yobarnacle
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    Yobarnacle Senior Member holding true course

    I'm not disputing you. The old ships had inch thick plate and the horizontal seams were doubled so 2 inchs thick. The ice wasn't thin sheet ice though. Ice cracks from wind stresses and the ice sheets ride over each other and freeze together again and again. We have been stuck 5 miles from the seabuoy on occassion because the ice went all the way to the bottom. We would travel in a convoy in line. The lead ship kept a 2 to 2.5 mile lead. Because when she got stuck, she'd back up 2 miles, pour the coal to her and ram again, untill busted through. we'd navigate in the ice cracks that were going generally where we wanted to go, then we break ice to get in a better crack when the crack deviated too much.
    Sounded like living in a continuos train wreck. Very noisy business breaking ice. :)
     
  8. Angélique
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    Angélique aka Angel (only by name)

    I was away from the web when this thread started and quick scanned over the first pages before I joined, but I missed the stabi not being hit mentioned early in thread by Daiquiri [​IMG]

    For those intersted in the not hit stabi, it's mentioned and discussed till now in the posts - #28 - #39 - #42 - #721 - #742 - #744 - #747 - #762 - #763 - hope I didn't miss any . . ?

    Sorry Daiquiri for my doubles about this, luckily the responses brought up interesting views about the subject :)

    Just did a web search on this topic for more info and of course landed in this thread :D

    Cheers,
    Angel
     
  9. nettersheim
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    nettersheim Consultant

    Thank you BPL and Annex for site references quoted (posts 787 and 788).
    They are providing some fundamental informations.

    The pictures of "Costa Concordia" 's abandoning and evacuation (seen from the starboard side) are quite interesting. They show clearly that evacuation has been rather very well carried out and that the crew looks to have behavioured professionnally despite some medias reports in the first hours and days. There is no indication of time for this pictures (or maybe I have missed something) ; this would be of most importance to get this info for evacuation analysis. The report of the vessel's chaplain is also worth to be read.

    Francois-Xavier Nettersheim
     
  10. nettersheim
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    nettersheim Consultant

    In USA Travel quoted by Annex in post 788 there is following statement from Prof. D.Vassalos. First time I see some reaction from one of the most influential person in nowadays naval architecture circles.

    QUOTE <<<Why did the ship roll on its right, or starboard side, when the gash in the vessel was on the left, or port, side? In addition to a possible failure of the water-tight compartments, wind, currents and maneuvering of the ship could tilt the wounded vessel away from the damage, says Dracos Vassalos, professor of maritime safety at Britain's University of Strathclyde.

    "The internal architecture of cruise ships is so complex that even with the same effects being accounted for in … experiments, computer simulations or, indeed, in real-life accidents, we could potentially see a different outcome every time we simulate the accident," Vassalos says.>>> UNQUOTE

    I am afraid we have to wait a lot to get more...

    Francois-Xavier Nettersheim
     
  11. daiquiri
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    daiquiri Engineering and Design

    No problem Angel, it always happens when the number of pages in a thread becomes large. Due to time constraints, usually only a first and a last couple of pages are read by newcomers. :)
    Cheers.
     
  12. bjornb
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    bjornb New Member

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  13. janneke
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    janneke New Member

    Hello Mr N
    I did some research on the internet to prove what i said about twin screws
    Here below is some information:

    Xtracted from Wikipedia :
    A propeller that turns clockwise to produce forward thrust, when viewed from aft, is called right-handed. One that turns anticlockwise is said to be left-handed. Larger vessels often have twin screws to reduce heeling torque, counter-rotating propellers, the starboard screw is usually right-handed and the port left-handed, this is called outward turning. The opposite case is called inward turning. (see also en.wikipedia.org/wiki/Propeller )

    Youtube movie about the azipod drives of Freedom of the seas:
    http://www.youtube.com/watch?v=skMd8Yi6th8 at about 1min 50 sec : view from the rear of the three azipods on the Freedom
    If one looks closely , one can see that one prop is Lh and the other RH

    Extracted from : http://www.windwardtechnologyhawaii.com/ship_simulators_000001.htm
    Rotation of a propeller has several effects other than driving the ship forward or in reverse.*
    Rotational Direction Effect.- The direction of rotation will turn the ship. With clockwise rotation, the stern will turn to starboard, the direction in which maximum sideways thrust is exerted. The opposite is true for counter-clockwise rotation. For this reason, if the ship has 2 propellers, the starboard prop has clockwise rotation and the port prop has counter-clockwise rotation to cancel the rotational direction effect. When only one propeller is in use, this effect must be taken into account. In the picture above, notice the opposite pitch of the port and starboard propellers.*

    On this site one can see the QM2 with the 4 azipods : 2 fixed up front and 2 rotatable. On the latter one can see the “handedness” of the props and consequently their counter-rotation property.
    http://malcolmoliver.wordpress.com/tag/azipods/
    I have tried to attach two foto's , look there at the asymmetric shape of the propeller blades, to see which way they rotate. But one thing is for sure : they rotate in opposite direction.
    Bye now
    JP
     

    Attached Files:

  14. nettersheim
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    nettersheim Consultant

    Hello Janneke,

    You did a considerable research job !

    But be careful with different things:


    1) pods are completely different compared to propeller with shaftlines ; you can't compare their behaviour with conventional twin propeller arrangement

    2) with twin propeller arrangement propeller are always turning on CW the other one anti CW; the big question is which one is CW and which one is anti CW ...

    3) as already mentioned there is no imperative rule regarding twin propellers arrangement; on the Epic they have choised inner rotation : port propeller CW and starboard anti CW ... but ... but these are fixed pitch propeller which is again something very different compare to variable pitch propeller where you may have a different choice !

    4) the last word is always for the tank test (especially with variable pitch propellers) .

    Francois-Xavier Nettersheim
     

  15. nettersheim
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    nettersheim Consultant

    I beg your pardon for my gobbledegook in my last post , § 2 ; please read :

    2) with twin propeller arrangement, you have always one propeller turning CW and the other one anti CW ; the big question is is which one is CW and which one is anti CW ...

    Francois-Xavier Nettersheim
     
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