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Old July 20th, 2006, 01:00 PM
Rev22:17 Rev22:17 is offline
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Join Date: May 2003
Location: Massachusetts
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Paul,

I noticed a lot of media coverage from the major networks, which you can usually find online. Interesting no one onboard managed to grab a video camera and tape it, as usually happens. But that actually says to me it was a scarier experience than it actually sounds.

Yes. Either people were too focused on hanging on for dear life or the event happened too quickly to think of reaching for a video camera.

Then again, a sudden list probably would have sent video cameras hurling, too, if they were not stowed....

The ship stayed at that angle for a good 30 seconds, usually when a ship rolls it starts to come back almost right away.

I still have not seen a report that states what "that angle" was, but it's fairly obvious that it was much larger than normal for a cruise ship, where passenger comfort is a major concern.

In any case, the behavior of the ship that you describe actually is quite normal and entirely predicted by the laws of physics. The combination of the centripetal effect on the ship's center of mass, whch is well above the waterline, the maneuvering forces, which act below the ship's waterline, creates a torque about the ship's roll axis that causes the ship to heel to an angle where the shift in the center of bouyancy counteracts the torque. Thus, the amount of heel increases with greater rudder angle applied to execute a tighter turn and with higher speed, which causes the ship to turn more quickly for a given rudder angle. These heels usually remain pretty steady for the duration of the turn. As the ship comes out of the turn, the torque from the turn diminishes and the bouyant forces right the ship again. Cruise ships obviously use only small rudder angles to execute normal maneuvers, especially at high speed, to prevent this sort of upset.

That would lead to the fear factar as well, as such a sudden change in pitch that did not immediately resolve itself would really start to make me wonder what had happened.

Yes, the heel would be very disconcerting for the majority of passengers, who do not really have a sense of how a ship reacts during a sharp turn. Of course, unsecured objects hurling across the ship, cabin, etc., would be even more disconcerting....

And what a sense of relief when she finally righted herself.

Yes, but I'm sure that the majority of the passengers -- and probably many of the crew -- were pretty badly shaken and not quite sure what to think. One of my dad's Navy buddies said that he was a beliver in terra firma -- the more firma (firmer), the less terra (terror). No doubt many passengers left the ship feeling the same way.

In any case, my curiosity would like to know (1) the speed of the ship at the time of the incident, (2) the rudder angle applied during the turn, and (3) the amount of heel that occurred. If you see this information anywhere, please post it.

Norm.
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