Costa Concordia, 80 deg list, really scary !!

Discussion in 'Stability' started by smartbight, Jan 15, 2012.

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  1. Pascal Warin
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    Pascal Warin Junior Member

    You should be careful with such straightforward assessment.
    This ship is complying with SOLAS but not build to withstand a three compartments damage. Thus no calculation with such long breech has been performed.

    But of course, you may question SOLAS requirements.
     
  2. Heiwa
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    Heiwa Naval architect

    IMO in London only organizes meetings (I have attended plenty) for their members so they can agree to, e.g. SOLAS. It is then the IMO members that try to apply the SOLAS requirements to their ships that are certified accordingly.
    The SOLAS rules, evidently, do not allow watertight doors between stores and crew spaces on passenger ships. But individual IMO members may interpret the rules differently ... and allow watertight doors (where they should not be). If you do not agree ... you have no chance.
    The only clear on this IMO member is actually the USA! When The USA could not agree to the MARPOL rules September 1997 they simply informed IMO that any ship coming to USA had to be certified according US local rules. USA does not accept the MARPOL rules! IMO approved Coulombi Egg tankers cannot enter US ports. They spill too little oil in any accidents. So much for free trade and liberty.
    Prove me wrong and earn € 1 000 000:-. Visit my web site.
     
  3. Heiwa
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    Heiwa Naval architect

    Back to topic!
    [​IMG]
    Can anybody explain to me what type of contact damages the vertical port aft side one meter below waterline down to the bilge on a ship ... but not its bottom?
    I will then update http://heiwaco.tripod.com/news8.htm#S
     
  4. smartbight
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    smartbight Naval Architect

    Here is my version:
    The Captain took the 'wheel' (joystick) for the 'sail by' at 15 knt (to impress the 'Moldovan beauty' next to him). He reported that he saw the white surf around 'Le Scole' on the bow. Too late! He knew he was in a jam. He swung the 'wheel' hard to stbd and the port side crashed into the rock, aft of the stab. fin. The deep floors (500mm c to c) in the double bottom put out a good fight, as shown on your photo, but the sudden 'shock' roll of the whole ship (20-30> deg) exposed the soft plating and long. above (3000mm c to c transv. deep frames). The fractured plating snatched that piece of 50-100 ton granite rock like a sugar tongue.
    The 3D chart of that 'can opener' rock explains the side damage.
    Nothing mysterious here, except for that 'Moldovan beauty'. Do they still say "cherchez la famme " in France ? Was she planted by the KGB or a competitor ? :confused:
    P.S.
    Same thing happened to the Capt. of the nucl. sub. "Greenville". Distracted by 1/2 dozen US beauties around him he rammed that Japanese ship 'kamikaze' style, 50 years after Pearl Harbor ?? :eek:
     

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  5. Heiwa
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    Heiwa Naval architect

    Thanks - so the port bilge 8.5-6.5 m below water aft of the extended stabilizer fin (not damaged) contacted the sea floor (at some starboard turn) and sheared off a 100 tons piece of granite sea bed. Ship listed for some reason to port and scooped up the 100 tons granite rock piece so it pushed in the ship's vertical side above the double bottom and then loaded itself on the double bottom pushing in the vertical side up to 1 m below waterline. Then vessel bounced off the obstruction so prop/rudder went free.
    Sorry, I don't think it is possible. :rolleyes:
     
  6. IEWinkle
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    IEWinkle Retired Naval Architect

    I don't see why not. The initial impact with the rock in the form of a side swipe at or around the bilge (at a draft of about 7.5 m) would have provided a lateral thust to the vessel which would have induced futher roll to port allowing the rock to rip open the relatively soft side shell above (longitudinal framing supported on web frames at 2900 mm intervals). Note the longitudinal hard point just below the waterline where the lower deck meets the side shell providing a resistance to further roll and a perfect baseball glove to catch the rock between it and the tank top - and what is probably an engine room bulkhead aft, shearing it from its reef. The rudder and propeller were well inboard of the line of impact and there is no reason the believe that they suffered any damage. The diver video of the strike area clearly shows a near vertical rock outcrop dropping away well below the vessel's 8.2 m draft.

    The stabiliser fin was above the original impact line and propably swept just above the offending rock outcrop in a relatively near miss.
     
    Last edited: Feb 13, 2012
  7. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Any thoughts on why the ship increased speed to 16 knots before impact?
     
  8. Heiwa
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    Heiwa Naval architect

    Definition of an outcrop is a visible part above ground/seabed so if stabiliser fin at 6 meter draught passes it we know the top of the outcrop is at >6 meter depth. This outcrop thus contacts bilge and rips it open (fair enough) ... what I cannot understand is that now 100 tons of the outcrop is supposed to be sheared off and then damage the vertical side up to 1 m below waterline ... and lodges itself on top of the inner bottom of the ship itself (which looks like magic). :?:
     
  9. IEWinkle
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    IEWinkle Retired Naval Architect

    It only requires that the vessel rolls to port by approx an extra 10 degrees (under the action of a large reactive side force some 12 m or more below the centroid of the vessel) with the shearing action taking place as the outcrop became entapped in the hull and probably hit by the bulkhead structure at some 10 or more knots. For a loss of speed of 7-8 knots over some 50 m of travel the average friction/shearing force on the rock over the approximate 5 secs of impact would be of the order of 85-90,000 tonnef. This seems more than enough to tear off a large chunk at or near the end of the process! I don't see the need for any magic!
     
    Last edited: Feb 14, 2012
  10. nettersheim
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    nettersheim Consultant

    You are right, we must at time assume that the vessel is supposed to comply with SOLAS with 2 compartments standard.

    We also must question SOLAS requirements. "Costa Concordia" has been designed according to SOLAS 90 (with amendts). These deterministic rules have been considered not good enough for large passenger vessels and for this reason Int. Marit. Org. has developped (from the late 90s up to 2006) a new set of rules paradigme the so-called SOLAS 2009 probabilistic rules. Such changing of principles was a way to hide the shortcomings of former deterministic rules for large passenger vessels (which are the rules of most of current passenger vessels).

    The question is : what about the SOLAS 2009 probabilistic rules ? They have not been basically developped with the aim of making progress in safety level even if in the process of their development some improvements have been done.
     
  11. Pascal Warin
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    Pascal Warin Junior Member

    Actually Reg.8 of the new SOLAS 2009 (probabilistic) is re-using in a hidden way the former deterministic requirements.
    This means that new SOLAS 2009 is requiring same level of safety as previous one plus something.
    Whether this "something" is enough is difficult to evaluate.

    What appears for sure is that design of SOLAS 2009 compliant vessel requires more cautious approach regarding progressive flooding through pipes, air conditioning casing a.s.o.
    This comes from the fact that all possible breeches need to be considered up to center line and there disappear the good old B/5 breech limit inside which you were supposed not to have any trouble and be allowed to do any funny things.
     
  12. Heiwa
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    Heiwa Naval architect

    Ok, ship's draught is 8.5 m, say, vertical side below waterline is 6.5 m, bilge radius is 2 m (same a height double bottom). 10° permanent heel puts top of bilge 1.14 m inside side at WL. Say B = 36 m. Inside of bilge will be 2.82 m below keel at CL, i.e. vessel's draught at inside bilge increases from 8.5 to 11.32 m, when heel is 10°.
    Now - where is this granite outcrop on the seabed that is sheared off a contact?
    In my opinion it is more probable that vessel contacts the bottom at inside bilge than anyting in the side above bilge/inner bottom. :rolleyes:
    That's the purpose of a double bottom. ;)
    That a ship's side can shear off anything from the seabed and flip it onto the top of the inner bottom after the side has been pushed in 3 m and is damaged up to 1 m below waterline is ... magic! :?:

    It has been suggested elsewhere that the sharp turn starboard caused a 20° heel to port (so everything on the tables in restaurants flew away), which means that the draught at inside bilge would have increased from 8.5 to 14.32 m. Don't you agree it is more likely that the inside bilge area of the flat bottom is more likely to contact the seabed than anything higher up in the vertical side above the rounded bilge?

    Underwater photos show something looking like the bilge keel being rolled up on the sea floor. If the bilge keel was fitted 1 m above baseline (7.5 m below waterline) and 17 m from centerline, it drops down to 13.69 m below waterline at 20° heel. It would appear the contact may have been at 13-14 m depth. So how then flip up a 100 tons granite piece of rock from that depth?
     
  13. Pascal Warin
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    Pascal Warin Junior Member

    20° is enormous heel. I don't trust that turning at full speed can create such heel.
     
  14. Heiwa
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    Heiwa Naval architect

    Well, somebody blames the Master having produced a sharp turn starboard (rudders swung out 35° which takes at least 20-30 seconds) when ship was doing 15 knots and as a result the vessel heeled 20° to port during the long starboard turn and as a result of that all food/porcelain/glasses on all tables in all the restaurants/bars flew down on the deck with sitting/standing passengers.

    And after that, during the starboard turn, vessel apparently contacted a rock outcrop on the seabed and sheared off a 100 tons boulder, etc, etc.

    I don't believe it but plenty of people say it happens all the time. I just try to visualize how anybody damaged the vertical side of the ship up to 1 m below waterline leaving (apparently) the flat bottom inside the bilge intact.
     

  15. Pascal Warin
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    Pascal Warin Junior Member

    When in the navy I happened to be on wheelhouse of a mine sweeper which rolled 12°.
    The feeling is like being on roller coaster in free fall !!

    Dining room in such vessel like Costa Concordia are rather high, thus it is not a surprise that passengers estimate roll far beyond actual one.
     
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