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Re: [Phys-l] hurricane question



Large ships may be more stable, but some small ships can also be very
stable, but not in a hurricane. Sailing ships do not roll much when the
sails are up. I went on a very small ship aroung the Bahamas with a tiny
passenger capacity, but it was a sailing ship. It sailed at night, but had
an engine just in case the winds were not good. So at night we had a good
rest with only a little gentle rocking. But during the day it put down
anchor and then it wallowed. But we all jumped into the ocean to either
dive or snorkel around the fantastic coral formations.

The one problem with sail is that if you have a good breeze in the early
morning, half of the ship rolls out of the bunks, while the other half
snuggles in.

I was under the impression that large ships also have a stabilizer to dampen
the rolling. Sail only dampens the sideways roll. And of course we steered
well clear of a hurricane, and raced it to Miami. But it didn't follow us.

John M. Clement
Houston, TX



Jack,
I looked up the size comparison of the Nimitz class carriers and the
current fleet of cruise ships. We were on the Adventure of the Seas
(Poyal Caribbean). That ship is 1020 feet long and has a tonnage of
137,000+, top speed of 22 K. This is what they call the Voyager class
of ships which has several other sister ships all built between 1999
and 2002. Royal is now building the largest cruise ships called the
Oasis class which will be 1181 ft with GNT = 220,000. The QM2 by
comparison is 1132 ft and GNT 148,000.
Wikipedia lists the Nimitz carriers as 1115 ft and 104,000 tons with
top speed of 30 K.

These cruise ships are remarkably stable and in 20 ft swells in the
fringes of Omar the ship hardly ever *rocked and rolled*. We once
cruised the north Atlantic out of New York on a smaller ship, the
Nodic Empress (since rechristened but I don't recall the new name) to
Bermuda. Now, that was a real *rock and roller* making the entire
dinner table retreat to their cabins the first night at sea. My
friend and I were the only ones left *alive* at the table at the end
of the evening and even my wife, intrepid sailor that she is, was in
bed that night by 7 pm.

On our previous cruise (Voyager of the Seas) they had a complete
oceanographic lab on board and we jumped at a chance to go on a tour.
The University of Miami set it up with a team of scientists and the
only thing the cruise line demanded was that they give tours daily for
passengers who signed up. Otherwise the scientists and the lab were on
board *rent free* for the week. Fascinating! My wife jokingly
asked if they needed teachers to give tours. They actually said yes,
so I wrote when we got home, sent them my credentials (no ocenaography
experience needed, so they said), but we never heard from them. Oh,
well... I suppose we will always have to pay our own way.... ;-)

Marty


On Nov 8, 2008, at 1:31 PM, Jack Uretsky wrote:

Hi Marty-
I was struck by "these huge cruise ships". As one who has been
through a numbeer of hurricanes in the Atlantic, mostly on 30,000 ton
aircraft carriers, your cruise ships are not that huge. Nothing, in
fact,
made by man is THAT huge, when mother nature really gets into one of
her
frenzies. Our carrier was a midget, in the late forties, compared
even
then with the Midway class, and one of those, steaming in our
company, had
aircraft wasshed off the flight deck. We pitied the poor destroyer
sailors, tossing and bobbing as they kept their stations on the edge
of
our task group.
I think that Brian summed up the present state of knowledge of
hurricane dynamics pretty well. Weather prediction is one of the
future
targets of future large scale computer evelopment.
Regards,
Jack



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