Last voyage for Costa Concordia cruise ship

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

  1. Minusadegree
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    Minusadegree Junior Member

    Stabilizer or Stabi. Like the flap on an aircraft wing designed to redirect the airflow to force the wing in either an upward direction or downward direction thereby moving the entire structure.
    My uderstanding in this context of bending would mean the direction of flow? Bending the direction of the ship.
     
  2. Angélique
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    Angélique aka Angel (only by name)

    My guess is that Janneke stated ‘‘the listing (in italian: bending) of the ship’’ to explain the word ‘‘listing’’ for Gian as he had stated several times ‘‘bend’’ where ‘‘listing’’ was meant. So just some extra explaination what was meant by the word ‘‘list’’ in this context.

    Cheers,
    Angel
     
  3. Yobarnacle
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    Yobarnacle Senior Member holding true course

    I think I suggested in an earlier post they were quoting us.

    :D:p
     
  4. Yobarnacle
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    Yobarnacle Senior Member holding true course

    Sorry angelique for mis-reading.
    Twin screw vessels almost always have props counter rotating in this sense. There are two options with different advantages.
    Inboard turning props. The starboard propeller turns counter clockwise while working ahead. The Port prop turns clockwise. Advantage is more speed as the "wake" is centered and also enables the vessel to "walk". Though this size of vessel wouldn't likely walk (move sideways with main propulsion.) Disadvantage is loss of turning ability. Vessels equipped with DP and I imagine liners are, usually have this arrangement.

    Outboard wheels are opposite turning than inboard wheels moving ahead. Greater control and turning abilty. Important on Tugs. Have to turn more than one vessel.
     
  5. Yobarnacle
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    Yobarnacle Senior Member holding true course

    I worked with a company, that the office actually explored the concept of a stress meter to be worn by the watch officer. If his stress rose above a spec'd limit, it would trigger alarms at office!

    What could the office do? They aren't aboard. ridiculous.

    i always wondered how the proposed stress meter would have been worn. Between the gluts sensing clinch?

    :D:p:D:cool:
     
  6. Gian Milan

    Gian Milan Previous Member

    Dear Minus, I'm sorry ...
    it was a rhetorical question, addressed to the poster.

    As you can see Angel has realized immediate (but I had no doubt).

    My company has also built small stabilizers.
    Customer wanted to do some test and we made some prototypes, so I know them pretty well.

    I am really happy that despite the "Italian bending", my thought is perfectly perceived.
    I can only thank my exegetes that elegantly, to prevent my thinking be misunderstood, correct the terms I use improperly.
     
  7. Minusadegree
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    Minusadegree Junior Member

    Lol, I could see why captains wouldn't want a system like the one I mentioned, but thats not to say that it would have to contact anyone outside of the ship. We have AIS that anyone can monitor, thats if someone was paid to look. Nobody wants big brother over the shoulder.
     
  8. peter radclyffe
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    peter radclyffe Senior Member

  9. smartbight
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    smartbight Naval Architect

    My apologies for the low-res picture.

    Looks like the boulder is right smack in the engine rooms and beyond. Which explain the nice white paint seen through the breech.
    No wing tanks to protect those vital compartments ?.
    No wonder it was all flooded down there ! Any collision with a rock, a ship, an iceberg, and we are back to 1912 !
    Good old Harry Benford would have given us a C- if this had been our final design project.

    If you find the tank & machinery arrangement plans on the internet can you please post them.

    P.S.
    We are not trying to be 'Doom & Gloom' as posted by some. We want more of these really amazing vessels built (more work for us) but if the damage stability is not improved, the tourists are going to wise up. Granted we can always turn it into a much improved prison ship and anchor it off Alcatraz !
    http://en.wikipedia.org/wiki/Prison_ship
     

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  10. Yobarnacle
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    Yobarnacle Senior Member holding true course

    I was curious also why no "double" hull in vicinity of engineroom. Almost every vessel I've run had engineroom lined with waste oil tanks, lube oil tanks, fire suppressant liquid tanks, day tanks (fuel), slop tanks, ballast tanks, potable water tanks, ect. It's why the engine room is such a preffered "safe" room during pirate attack. Any bullets penetrate the shell, liquids leak out, not in. :)
     
  11. janneke
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    janneke New Member

    Hello Mr Nettersheim
    Ref deployed stabi :
    does anyone out there have an explanation WHY the stabi was deployed? I agree partly with your arguments, but a ship that just leaves port does NOT need a stabi, and the accident only happened 2 or 3 hours later and the weather was not stormy enough to need a stabi. So why then deploy this device? Nobody seems to have noticed or explained this!

    I will try to clarify another phenomenom:
    I made a little planview sketch of the Concord :
    the port fin is located approx 120 m from the bow , the start of the tear in the hull is ~ 60 m after the fin while the tear is ~ 60m long (one source even says it is 50 m long) till where the boulder is jammed in the hull. If i draw a line between where the rock is jammed (and i assume the rock is 2 m in diameter ) and the start of the tear in the ship”s wall, then by triangulation the angle of incidence is apprx 1-2 deg. When i draw a similar line thru the fin tip (i guess the fin is 5 m long) and the start of the tear, the angle is 2-3 deg. In other words both these lines are not in eachothers prolongation, If they would have been in line the boulder would have been imbedded deeper in the ship. An explanation for the second line's smaller angle may be due to the friction of the accident.
    But a 100,000 ton ship is not easily pushed away by a piece of stone. And once the rock was detached from the island, there was no obstacle anylonger to create friction.

    But here i think i have proven that the stabi was not deployed at the time the ship hit the rock.

    The ship started to turn only a few minutes before the impact, not in time to actually start turning due to to the inertia. Let's not forget that this is a 100,000 brt ship that reacts with a lot of delay and that still sailed at 16 knts. Before it actually starts turning, minutes go by. And the turning radius of these type of ships is BIG, very big. Don't forget the Concord had traditional (counterrotating) propellers and rudders. They don't turn as quick as the ships with azipods.

    Why the counterrotating props? Because this way they eliminate the rotation momentum. All ships with two props have this.
    Submarines also have two props, but in concentric mounting on one shaft and counterrotating as well.
     
  12. nettersheim
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    nettersheim Consultant

    Hello Janneke,

    I don't want to play the guy who never agrees but again I will do, I must apologize for this !

    Things are alaways more complicate than expected... Regarding the main propellers, it is a common but false idea to consider they should be counterotating. On passenger vessels (cruise and ferries) the choice is always made based on the towing tank tests which determine the best water flow lines for propellers in all operative conditions. The consequences in terms of side forces, side momentum, etc in between outer and inner rotation for propellers are of second order compared to the water flow pattern importance. Therefore at time nobody can tell which solution has been adopted at Costa Concordia project stage and only people from Costa technical department or Captain or Chief-Engineer would be able to answer (together with shipbuilder Fincantieri).

    Concerning the fin stabilizer, I don't know the Costa procedure, but according to my experience (large ferries in English Channel and North Sea), some companies ask their captains to extend fin stabilizers as soon as they are living ports except obviously if weather is definitely calm. The extra drag is considered as a minor drawback compared to platform stabilisation for passengers. Anyway, I still do not understand what would have been the idea of the people on the bridge whether they extended port fin. For which purpose ? As already mentioned in previous post it would have given no result with nearly zero speed condition. You don't fight a compartment flooding with a fin stabilizer !

    Again, at time, everything is speculation including my above feeling...

    Francois-Xavier Nettersheim
     
  13. peter radclyffe
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    peter radclyffe Senior Member

  14. Gian Milan

    Gian Milan Previous Member



    much worse, I dare say.
    ships in 1912 had fewer passengers.
    Few lifeboats that there were could be lowered into the water.
    Many similar vessels sailed a short distance on busy routes.

    However in 1912 they had all entrusted to the great designers that, having regard to considerations of traffic, given the numbers, all evaluated with great intelligence, thought adequate lifeboats for only half the passengers.

    Something makes me think that the designers have had children and grandchildren.
     

  15. BPL
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    BPL Senior Member

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