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    Re: A credible AIS track for the Costa Concordia
    From: Lu Abel
    Date: 2012 Jan 25, 09:24 -0800
    The seemingly increasing top-heaviness of cruise ships worries me.  I wonder what their stability or righting-moment curves look like.   Such a curve is very familiar to sailors -- tells how far a sailboat can roll before it wants to point down instead of up.   For the typical monohull sailboat, the tip of the mast can be brought down to the water and the boat will handily right itself.   Usually takes a heel of 120~140 degrees before it will not right itself.

    I realize one can achieve great stability in ships by taking on ballast water, but I nonetheless have to wonder how any amount of water ballast 20 or 30 feet below the water can right stem-to-stern steel superstructures 100 feet above the waterline from all but the most trivial heel.

    Lu Abel

    From: Greg Rudzinski <gregrudzinski@yahoo.com>
    To: NavList@fer3.com
    Sent: Wednesday, January 25, 2012 6:13 AM
    Subject: [NavList] Re: A credible AIS track for the Costa Concordia

    Lots of excellent analysis from the list.
    The ship should also be analyzed as to why it couldn't sustain a rip in the hull and stay afloat. An excessively high center of gravity by design may have compromised the ships stability. Accidents still happen even with fail safe devises and well trained crew in place so naval architecture needs to keep up to reduce the consequences of groundings, collisions, and acts of war .
    Greg Rudzinski
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