Wonder why ships don't tip over?

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#1
Central FL
422 Posts
Joined Jan 2008
I do. I remember when ships had heavy, deep keels as ballast. Their draft was so deep they couldn't get into shallow ports, (remember the Cunard France always anchored outside St. Thomas bay?)
It is my understanding that newer ships have more of a flat bottom instead of a pointy keel (and they draft shallower), then huge water holding tanks inside the hull act as ballast. These are controlled by computers to keep the ship level and up.
Anyone knows more about this?
#2
1,864 Posts
Joined May 2009
Originally posted by gonzo1124
I do. I remember when ships had heavy, deep keels as ballast. Their draft was so deep they couldn't get into shallow ports, (remember the Cunard France always anchored outside St. Thomas bay?)
It is my understanding that newer ships have more of a flat bottom instead of a pointy keel (and they draft shallower), then huge water holding tanks inside the hull act as ballast. These are controlled by computers to keep the ship level and up.
Anyone knows more about this?
Actually an interesting question, but I don't have an answer.

But I betcha Hank knows the answer? Perhaps ask him.

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#3
435 Posts
Joined Apr 2010
Originally posted by Yo Eleven
But I betcha Hank knows the answer? Perhaps ask him.

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Marginally better than Cynthia McKinney, but still a state embarrassment.

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#5
Lynn Haven, Fl
2,736 Posts
Joined Mar 2007
Fixed ballast, very wide beam, high cube design, water ballast, are all elements that combine to give a very stable ship with a draft of less than 26 feet in most cases. The deepest draft ship running until recently was the old Regal Empress which drew at least 32 feet. She was built in 1953, so that makes sense.

The modern cruise ship is flat bottomed and slab sided. This is why they are very stable.

A very good discussion about this aspect of ship design can be found in George W. Hilton's book Eastland: Legacy of the Titanic. The Eastland capsized in the Chicago River in 1915. It is out of print, but should be available at Amazon or ABE Books.

Doc
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#6
Florida
570 Posts
Joined Mar 2010
http://www.youtube.com/watch?v=deX7R9RbmX0 - Here is a video of very rough seas with a cruise ship.

I also dug up this realic from the past http://boards.cruisecritic.com/showthread.php?t=154578
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#7
Michigan
374 Posts
Joined Oct 2009
Originally posted by gonzo1124
I do. I remember when ships had heavy, deep keels as ballast. Their draft was so deep they couldn't get into shallow ports, (remember the Cunard France always anchored outside St. Thomas bay?)
It is my understanding that newer ships have more of a flat bottom instead of a pointy keel (and they draft shallower), then huge water holding tanks inside the hull act as ballast. These are controlled by computers to keep the ship level and up.
Anyone knows more about this?
If I remember right, believe it's called draft, the Valor goes 28' under the water line, 3 floors plus, and the engines are down there, very heavy..
#9
Rome,Ga
105 Posts
Joined Jul 2003
Originally posted by gonzo1124
I do. I remember when ships had heavy, deep keels as ballast. Their draft was so deep they couldn't get into shallow ports, (remember the Cunard France always anchored outside St. Thomas bay?)
It is my understanding that newer ships have more of a flat bottom instead of a pointy keel (and they draft shallower), then huge water holding tanks inside the hull act as ballast. These are controlled by computers to keep the ship level and up.
Anyone knows more about this?
I think it is probably related to the concern that Congressmn Coleman made in a Congressional hearing a few weeks ago about the possibility of Guam tipping over because it would become too populated if we enlarge our military base there. The cruiseships are not islands so I'm sure they wouldn't tip over.
#10
Texas
913 Posts
Joined Sep 2008
This is the real reason, you may wish the question had not been asked:

http://en.wikipedia.org/wiki/Metacentric_height

These ships are built of steel in the bottom, with the engines, fuel and ballast tanks down low to give lots of weight. The superstructures are aluminum and are basically huge empty spaces. Instant stability.
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#12
in the midwest
2,604 Posts
Joined Sep 2009
The financial liability would be enormous if modern ships were not built to be stable in even the worst seas. You're safe even in a hurricane as long as you don't get so drunk that you decide to take a nose dive off your balcony.
#15
Douglasville,Georgia
311 Posts
Joined Mar 2005
Originally posted by dd2355
Marginally better than Cynthia McKinney, but still a state embarrassment.

Props to the Admiral. I couldn't have held it together. (see vid @ 1:30)
I want to deny I even live in Georgia!! What a disgrace for a political leader. And that stupid ass is going to draw retirement and health care plus all the other benefits that a congressman gets for THE REST OF HIS LIFE!! It's a pity one can't resend the appointment.
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#16
Edmonton, Alberta, CANADA!
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I suggest that on your next cruise you sign up for the Behind the Fun tour and you can ask the chief engineer that very question!!!!
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#19
16 Posts
Joined Apr 2010
Originally posted by DocF
Fixed ballast, very wide beam, high cube design, water ballast, are all elements that combine to give a very stable ship with a draft of less than 26 feet in most cases. The deepest draft ship running until recently was the old Regal Empress which drew at least 32 feet. She was built in 1953, so that makes sense.

The modern cruise ship is flat bottomed and slab sided. This is why they are very stable.

A very good discussion about this aspect of ship design can be found in George W. Hilton's book Eastland: Legacy of the Titanic. The Eastland capsized in the Chicago River in 1915. It is out of print, but should be available at Amazon or ABE Books.

Doc
My first cruise was on the regal empress when she was the caribe I back in 1989.
Anyway like most have said here these ships have huge heavy keels google for some pics of some of these ships in dry dock you'll see.

KZ
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