Refloating the Concordia

Discussion in 'All Things Boats & Boating' started by Minusadegree, Feb 26, 2012.

  1. Frosty

    Frosty Previous Member

    I know you all waiting for me to come up with a good idea but to be honest with you I'm a bit baffled by this one.

    It will be worth quite a bit more now though with the serious mussel beds stuck to it. There could be as much as 1000 dollars of edible shell fish on it by now.

    Every little helps.
     
  2. bntii
    Joined: Jun 2006
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    bntii Senior Member

    You first- provide a 'proper engineering report' that concludes that the balloon concept is a viable approach in the case of the CC..


    My second criticism- buoyancy is a dynamic state.
    The simplest approach to shifting the wreck into deeper water is to provide lift on the inboard side.
    Give it a go and the ship is guaranteed to shift on the bottom.
    A slide into deeper water will result in a roll towards land that can't be controlled by compressors, their lines to bags and the lighters carrying the gear- all will be as risk as the rotation proceeds and there is no simple manner of limiting the oscillation caused till stability is reached. If it is in fact found with any portion on the ship still above water as the event proceeds..
    As the ships shifts, the real risk is taken that the hull will fail compounding the environmental cost. As the ship shifts, the bottom will be scoured causing greater damage then the piles placed in the platform approach.

    The diagram you linked to above is a artists rendition with wholesale assumptions over the evolution of the lift process.
     
  3. Jonno
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    Jonno New Member

    Your assumption that the ship will roll towards land when the wreck is moved seawards is incorrect.

    In the balloon method, the ship is actually "righted" by placing balloons on the inland side. As these are inflated, so THAT side of the ship starts to lift ie roll upright.

    Here's where your comment about "dynamics" does ring true. The ship is now also lighter, and because of this new dynamic, she now becomes lively, and starts to move to a new position of equilibrium downhill ie seawards and further down the slope.

    But - and it is the really important "BUT" in this development - the NEW angle that the ship has rotated to REMAINS - no matter what.

    So, if she was previously listing at 80 degrees or so, and she has now rotated to (say) 60 degrees, she will now - entirely due to the buoyancy added by the balloons, remain at this 60 degree angle. EVEN if (as suspected will happen), she slides (sinks!) into deeper water down the slope.

    It is entirely acceptable that this happens during the course of up-righting. And indeed, it is actually beneficial that this occurs!

    There is NO issue with air pumps not being able to keep up and prevent a roll. In the balloon method, these issues are non-events, and simply do not occur.

    Capiche? http://www.boatdesign.net/forums/images/smilies/smile.gif
     
  4. bntii
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    bntii Senior Member

    The stability open water is the issue.
    Partial inflation of bags may very cause the ship to shift in position - towards open water.
    If that shift occurs at any before the weight is born by the bags, the ship will rotate about its new cg.

    The lift diagram you provided assumes a stable grounding point around which the ship will rotate till the moment when buoyancy can be taken up by the bags.

    I don't buy it.
    Apparently the engineers in charge of the salvage design don't either..
     
  5. Jonno
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    Jonno New Member

    It is a key feature of the balloon method that the Concordia is secured to the shore with cables. So, the ship never moves seaward unless deliberately under control.

    Under these conditions, once the balloons take effect, and visibly start to rotate the ship, that amount of rotation (whatever it is) REMAINS positive, and does NOT disappear - even if the ship is deliberately allowed to move seaward.

    The "problems" you surmise simply do not occur.
     
  6. bntii
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    bntii Senior Member

    So external sponsons vs internal bags...?

    Both use cable to shore, both provide for lift to occur towards upright first then floatation.
    Internal adds the burden of bag placement and control with a 'do what you will' thinking towards how the ship takes to the bottom.
    External adds the platform to insure control.

    The discussion might be simplified if we think of the approach that would be taken if the ship was lying on a level sea floor.

    I believe external sponsons would still be the best choice.
     
  7. Jonno
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    Jonno New Member

    Whether the ship is lying flat on the seafloor, or on a slope, doesn't make any difference to understanding the dynamics.

    The problem with sponsons is that they are an external attachment to the side of the ship - which is a helluva problem when you need to attach them to the side that is lying against the ground, and you therefore can't easily place then in an effective position.

    Balloons are really easily placed inside the ship, and because the Concordia is a passenger ship, it has literally hundreds of small compartments. The advantage of these compartments is that they helpfully keep the balloons in their original positions ie they cannot go drifting off into some other part of the ship as the ship orientation changes (which wouldn't be a good thing).

    Adding sponsons to the Concordia is MAJOR engineering work - which takes a great deal of time, huge expense, is VERY risky work, and initially at least, is very difficult to get an effective result out of it (because you need to - but can't - get easy access to the side of the ship that is lying against the seabed).

    The other very real risks with sponsons is that they can break away during the righting motion. If this happened with a ship of the size of the Concordia, the consequences will be catastrophic - if not even fatal.

    The solution seems an absolute no-brainer to me.

    In THIS particular situation of the Concordia (I'm NOT generalizing this to other salvage situations, where other factors may over-ride), deploying a few hundred (even a few thousand) balloons at what has to be a ridiculously minimal cost and with very easy and simple deployment, will have the Concordia re-floated and into dry-dock before the draftsmen have even finished the drawings for the sponsons, never mind waiting for the salesmen getting around to submitting their quote for the job!
     
  8. bntii
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    bntii Senior Member

    Will be interesting to see as the work progresses.
    Anyone know when the salvage gets underway?

    Jonno- don't you think that if internal balloons were "an absolute no-brainer" that this solution would have been selected by the pros?
     
  9. Jonno
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    Jonno New Member

    It is quite clear that this method was completely overlooked initially.

    Each salvage firm has their own favorite "go-to" solutions. And this mind-set is very entrenched. Some people like a BMW, others think Mercedes is THE car.

    Basically, quick and efficient salvage techniques are NOT very profitable compared to complex, drawn-out methods. If a stranding can be turned into a wreck-removal exercise, rather than a mere re-float, then it becomes really profitable. There is no incentive not to encourage this outcome either.

    AND ... there are massive EGO's involved in these companies. Nobody wants to be seen to be adopting some other salvor's idea! And to admit now, that there exists a better idea - AFTER they have announced their "Grand Plan". Heaven forbid! Never going to happen.
     
  10. bntii
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    bntii Senior Member

    I don't agree with any of that.
    Are you the author of that blog?
    Don't quit your day job if you are..
     
  11. Jonno
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    Jonno New Member

    You sound a tad too defensive. Have we touched a salvor's nerve?

    If you can't justify your opinion, don't resort to sarcasm - it doesn't impress.
     
  12. bntii
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    bntii Senior Member

    You read the blog I take it?

    "I have no experience"
    "I have no ideal how much this will cost"
    "I don't even know how to to this but will hire outside consultants to tell me how"
    "I am going to have the job done in two or three weeks and anyone who can't do it this fast is milking it.."
    "My plan is far superior to those who have extensive experience and know what they are doing"

    The web site/blog is a joke- thanks for posting it.
     
  13. Jonno
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    Jonno New Member

    You are rather liberal with your so-called "quotations" from this web-site. Rephrasing other people's sentences in YOUR own words, and then presenting YOUR incorrect and out-of-context interpretation in bogus "quotes" and thus attempting to pass YOUR garbage off as what the blog-site says, is just plain wrong.

    If you read these so-called statements in the context they are given in the blog, they sound pretty reasonable to me. It's really idiotic to find fault with a blogger who has the candor to admit he doesn't know everything (and you do?) and will resort to expert advice from knowledgeable consultants. That is a very sane thing to do!

    Are you actually suggesting that Titan, Smit and whoever else we care to think of, MUST actually ALSO be fools and not know what they are doing BECAUSE (gasp!) they ALSO resort to employing consultants???

    Every technical objection YOU have previously raised has been shown to be either lacking in knowledge (on your part) or has been thoroughly rolled back with a valid explanation.

    If you still have valid technical objections (and it is always quite in order to have these), then please remain civil, and don't descend into personal attacks or belittlement.
     
  14. macka17
    Joined: Jul 2012
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    macka17 macka17

    Hi.

    This could go on forever Yak Yak YAk..

    We've floated a few boats over the yrs. Up to a 100ft trawler.
    Only toys I know ..
    but only difference Basically. Is volume of vessel and buoyancy req'd to do the same job..
    Enuff space for the bags\pontoons. Internal\external. You can float anything.

    If they chain her to the rocks first. to stop any sliding.
    Fill the high side with floatation first. to counteract the over rotation And possibly weld a wing of some sort (like the sponson of a sailing cat??)
    to her at new calculated waterline. to help.
    Then fix and start to inflate the under\inside bags.
    she'll float and be stable.
    Then can be raised\floated to calculated waterline for safe towing..

    It'd be a prick to seal all the tears. AND the existing openings in hull.
    Don't bother. Just plate the main tears
    .Float with enuf buoyancy to suit tow.
    Then if extra lift.\less draught req'd for destination. External bouyancy to lift
    when they arrive.
    Lower in water for tow will be a lot more stable..

    Just my thoughts on it..

    But. there again. Bad weather comes.
    it all goes out the window.and we have a new diving wreck...
    Macka
     

  15. ancient kayaker
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    ancient kayaker aka Terry Haines

    I don't see how balloons can be used internally to refloat a passenger vessel of this size. It isn't constructed to support heavy spot loads. The largest volumes internally are probably swimming pools and ballrooms mostly roofed in glass, the upper decks are designed to support people not cargo, and the partitions are probably built closer to house standards than what you'd find in a cargo ship. Enough internal balloons to float it would destroy it first. Filling it with unrestrained air would be even worse.
     
    Last edited: Aug 5, 2012
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