United Airline
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How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 3:39 pm

How do stabilizers on ships work? Do they help a lot at rough seas?
 
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Dreadnought
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 3:56 pm



Quoting United Airline (Thread starter):
How do stabilizers on ships work? Do they help a lot at rough seas?

They are gyroscopically operated, and help mostly with roll caused by medium sized seas. Really rough seas will definately overwhelm their capabilities.
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bristolflyer
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 4:17 pm

I know of 2 different types of stabilizers. Firstly, fins that stick out from the sides of the hull (underneath the waterline). They slow the boat rolling by making it harder for the hull to move through the water.

The second one was very simple, but simple os good. I saw it on a large (about 80') motor yacht. It was a 1-ton weight on a rail inside the engine bay, the rail was mounted across the boat. I believe hat other than being able to lock the weight in position, it wasn't powered - it only ever rolled 'downhill'. So the boat would roll to port, the weight would roll that way and counteract the boat rolling back to starboard so quickly.

After writing this I did a wki search for you:

http://en.wikipedia.org/wiki/Ship_stabilizer
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astuteman
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 4:24 pm



Quoting BristolFlyer (Reply 2):
The second one was very simple, but simple os good. I saw it on a large (about 80') motor yacht. It was a 1-ton weight on a rail inside the engine bay, the rail was mounted across the boat. I believe hat other than being able to lock the weight in position, it wasn't powered - it only ever rolled 'downhill'. So the boat would roll to port, the weight would roll that way and counteract the boat rolling back to starboard so quickly.

This is done with tanks of water on some bigger vessels, which are "tuned" to the natural frequency of the ship's motion......
Simple, and elegant..  Smile

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United Airline
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 6:28 pm

Any pictures of it?

I was on Oceania Insignia around Cape Horn and it was very rough.

If I was on Grand Princess, Freedom of the seas or bigger ships will it be more stable?
 
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 6:56 pm



Quoting United Airline (Reply 4):
Any pictures of it?

There are several different designs. Most common look like stabilizers on a plane. They stick out of the hull and adjust to reduce the roll...
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DocLightning
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 7:04 pm

There are two basic kinds, as has been said here.

The first are a set of fins that stick out of the side of the hull. They simply change their angle of attack just like a plane's stabilizer to counter the roll. They can reduce the ship's roll to essentially nothing.

The second type is a pair of tanks of water with a high-speed pump that pumps water between them to balance the ship against rolling. I've been on this sort of ship, too, and they roll more, but it still takes the bite out of the roll. We were also doing the Drake Passage...
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 7:06 pm



Quoting United Airline (Reply 4):
If I was on Grand Princess, Freedom of the seas or bigger ships will it be more stable?

Bigger will always help. Bigger + stabilizers even better.
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Klaus
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 7:16 pm

An image search has turned up these:

Extended:


Retracted:
 
skidmarks
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 7:56 pm

Whatever they do I recommend a trip on the Ben my Cree from Heysham to Douglas in the Isle of Man in a force 8 gale. There you will feel exactly what stabilisers are incapable of!!! Big grin

And be very sick into the bargain!  vomit 

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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 8:07 pm



Quoting Skidmarks (Reply 9):
Whatever they do I recommend a trip on the Ben my Cree from Heysham to Douglas in the Isle of Man in a force 8 gale. There you will feel exactly what stabilisers are incapable of!!! Big grin

And be very sick into the bargain! vomit

I made the Drake Passage without getting sick. Second day of the voyage I felt a bit "off" but I was faring a lot better than many of the Russian crew, who were walking into walls (admittedly at times the walls seemed more horizontal than the floors) and looking a bit green. Meanwhile, I just seem to be immune to motion sickness.
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MCOflyer
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 8:28 pm

You can have whats called Paravane roll Stabilizers. Heres a photo of one:

http://www.tsb.gc.ca/en/reports/marine/1998/m98n0064/photo_1.jpg

Note the outriggers on the side of the boat. When one side goes down or up the other helps keep the boat level. Another form of stabilization is the sea gyro used for boats from 5-50meters. Heres more information:

http://www.abc.net.au/tv/newinventors/txt/s1415189.htm

Hope this helps,
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comorin
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 9:37 pm



Quoting United Airline (Reply 4):
If I was on Grand Princess, Freedom of the seas or bigger ships will it be more stable?

Even the biggest ships ( I was on the Monarch of The Seas), you can feel really tiny in a Hurricane! The force with which the ship smashes down on the waves, the groan of the steel beams, and the unsteady floors can be a truly terrifying experience even for hardened seamen. You keep waiting for the next wave, the bow of the ship rises, the rivets creak, and Bam!, the bow smashes into the trough, flooding the decks...it goes on interminably.

Stabilizers are great for damping rolling motion over normal range but are limited in their use in extreme pitching conditions.
 
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 9:48 pm



Quoting Comorin (Reply 12):

Even the biggest ships ( I was on the Monarch of The Seas), you can feel really tiny in a Hurricane! The force with which the ship smashes down on the waves, the groan of the steel beams, and the unsteady floors can be a truly terrifying experience even for hardened seamen. You keep waiting for the next wave, the bow of the ship rises, the rivets creak, and Bam!, the bow smashes into the trough, flooding the decks...it goes on interminably.

And you sit there wondering if you're going to capsize or break in two.
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 11:15 pm



Quoting MCOflyer (Reply 11):
You can have whats called Paravane roll Stabilizers. Heres a photo of one:

Huh, I thought those were for spreading fishing nets wide. I did a search and they have fin-like devices that cut throught the water beneath them.
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RE: How Do Stabilizers On Ships Work?

Sun Oct 26, 2008 11:25 pm



Quoting BristolFlyer (Reply 14):

Huh, I thought those were for spreading fishing nets wide. I did a search and they have fin-like devices that cut throught the water beneath them.

Heres more information:

http://www.kastenmarine.com/roll_attenuation.htm

Scroll down about halfway and you'll see the word "paravanes."

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United Airline
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RE: How Do Stabilizers On Ships Work?

Mon Oct 27, 2008 2:20 am



Quoting PPVRA (Reply 7):
Bigger will always help. Bigger + stabilizers even better.

How much of a difference between Grand Princess and Oceania Insignia at Cape Horn? It was really rough that time
 
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RE: How Do Stabilizers On Ships Work?

Mon Oct 27, 2008 2:38 am



Quoting United Airline (Reply 16):
Grand Princess

Seems not very easy to find data on MS Insignia, though from pictures, Grand Princess is MUCH larger.
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RE: How Do Stabilizers On Ships Work?

Mon Oct 27, 2008 2:43 am



Quoting DocLightning (Reply 13):
Quoting Comorin (Reply 12):

Even the biggest ships ( I was on the Monarch of The Seas), you can feel really tiny in a Hurricane! The force with which the ship smashes down on the waves, the groan of the steel beams, and the unsteady floors can be a truly terrifying experience even for hardened seamen. You keep waiting for the next wave, the bow of the ship rises, the rivets creak, and Bam!, the bow smashes into the trough, flooding the decks...it goes on interminably.

And you sit there wondering if you're going to capsize or break in two.

 yes 
 
United Airline
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RE: How Do Stabilizers On Ships Work?

Tue Oct 28, 2008 2:50 pm

Do stabilizers help a lot even in very rough conditions?
 
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RE: How Do Stabilizers On Ships Work?

Tue Oct 28, 2008 6:02 pm



Quoting United Airline (Reply 19):
Do stabilizers help a lot even in very rough conditions?

They decrease roll, which is the most uncomfortable motion just because of its frequency and magnitude. And they help a LOT. They do not, however, eliminate all sense of motion and they do nothing to decrease pitch.

But if a ship wants to pitch, let it pitch its heart content. It's roll that bugs me.
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United Airline
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RE: How Do Stabilizers On Ships Work?

Wed Oct 29, 2008 2:20 am

Roll means left and right movements right?
 
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RE: How Do Stabilizers On Ships Work?

Wed Oct 29, 2008 6:26 am



Quoting United Airline (Reply 21):
Roll means left and right movements right?

Port and starboard, but yes. Through the longitudinal axis of the ship  Wink

Pitch is the fore and aft "up and down" motion of the vessel, usually as it encounters swells.

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RE: How Do Stabilizers On Ships Work?

Wed Oct 29, 2008 6:38 am



Quoting Astuteman (Reply 3):
This is done with tanks of water on some bigger vessels, which are "tuned" to the natural frequency of the ship's motion......

Believe many skyscrapers have similar water tanks or other weights on their roofs, that also dampen the natural swaying of the building.

Quoting PPVRA (Reply 7):
Bigger will always help.

That's what she said  duck 
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United Airline
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RE: How Do Stabilizers On Ships Work?

Wed Oct 29, 2008 6:51 am

Up and down is ok. But left and right bothers me
 
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RE: How Do Stabilizers On Ships Work?

Wed Oct 29, 2008 7:10 am



Quoting Comorin (Reply 12):
Even the biggest ships ( I was on the Monarch of The Seas),

Although size isn't everything....  Smile

Most modern cruise liners are inherently disadvantaged by having a large metacentric height as a result of the draught being limited (for access to shallower harbours), and the beam being greater (metacentric height is a function of, amongst other things, beam/draught.

A large metacentric height increases the righting moment exerted on the ship when it rolls from side-to-side, making the rolling "stiff" and uncomfortable.

That's one reason for the "popularity" of stabilisers, these days..  Smile

The older liners were much better in this respect.
Ironic, I suppose, that this very "stiffness" is actually a sign of inherent stability - the less stable, the easier the motion..  Smile

Quoting Comorin (Reply 12):
the rivets creak

Rivets?
In this day and age?
 faint   Smile

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skidmarks
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RE: How Do Stabilizers On Ships Work?

Wed Oct 29, 2008 7:26 am



Quoting Astuteman (Reply 25):
Quoting Comorin (Reply 12):
the rivets creak

Rivets?
In this day and age?

Obviously he doesnt travel on the "right" sort of ship!! Big grin

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DocLightning
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RE: How Do Stabilizers On Ships Work?

Wed Oct 29, 2008 8:26 am



Quoting Vikkyvik (Reply 23):

Believe many skyscrapers have similar water tanks or other weights on their roofs, that also dampen the natural swaying of the building.

Works a bit differently. Those weights are basically dampers that increase the mass of the building and this 1) lower its intrinsic frequency and 2) make it so that the wind has to push harder to move the building.
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RE: How Do Stabilizers On Ships Work?

Wed Oct 29, 2008 12:53 pm

Try going on a Navy Frigate in the Southern Ocean at speed through 100ft ocean swells... the ship goes through the wave and is almost completely submerged before coming out the other side... My dad has done this many times and I've seen photos taken from a helicopter above of this.
No stabilisers however.

[Edited 2008-10-29 05:54:03]
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sprout5199
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RE: How Do Stabilizers On Ships Work?

Wed Oct 29, 2008 7:54 pm



Quoting DocLightning (Reply 20):
They decrease roll, which is the most uncomfortable motion just because of its frequency and magnitude.

I would have to disagree. The ship I was(FFG), rolled quite a bit, but didn't get too many people sick, but when we pitched a lot most of the crew was green. We did have fin stabs, but they were broke most of the time.

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RE: How Do Stabilizers On Ships Work?

Thu Oct 30, 2008 1:05 am



Quoting Zkpilot (Reply 28):

I would like to pics of this.

Also, I know a couple who have a Sea Gyro on their vessel and love it.

http://www.seagyro.com/

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Zkpilot
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RE: How Do Stabilizers On Ships Work?

Thu Oct 30, 2008 7:10 am



Quoting MCOflyer (Reply 30):
Quoting Zkpilot (Reply 28):

I would like to pics of this.

Its been a while since I've seen those pics... just tried to find them but no luck...
here are some other ones I have found online tho..

These waves are all much smaller than the example I was talking about earlier... but they are still good shots!  Smile
HMNZS Te Kaha (Frigate)

HMNZS Canterbury (Frigate retired)


HMNZS Waikato (Frigate retired)

HMNZS Te Kaha

Not sure... possibly HMS Jupiter or another RN frigate that may have been sold to RNZN
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MarSciGuy
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RE: How Do Stabilizers On Ships Work?

Thu Oct 30, 2008 10:19 pm



Quoting United Airline (Reply 4):
Any pictures of it?

I was on Oceania Insignia around Cape Horn and it was very rough.

If I was on Grand Princess, Freedom of the seas or bigger ships will it be more stable?

As other posters have said, yes bigger does help to some extent, but being you have to take into account where you are in relation to the vessels CG as well...if your moment arm is increased enough on a large vessel you'll certainly feel it!.

Quoting DocLightning (Reply 13):
Quoting Comorin (Reply 12):

Even the biggest ships ( I was on the Monarch of The Seas), you can feel really tiny in a Hurricane! The force with which the ship smashes down on the waves, the groan of the steel beams, and the unsteady floors can be a truly terrifying experience even for hardened seamen. You keep waiting for the next wave, the bow of the ship rises, the rivets creak, and Bam!, the bow smashes into the trough, flooding the decks...it goes on interminably.

And you sit there wondering if you're going to capsize or break in two.

I am a hydrographic surveyor and by definition (and contractual data quality obligation) we cannot survey in rough seas - (air under the xducer causing blowouts in the data meaning we are going ot have to re-do the survey lines anyhow) and I can tell you, especially from my last months' experience off of Delaware, that roll is predictable and can therefore be compensated for to some extent but unless you keep your body tensed up continually to compensate for the slamming sensation as the hull crashes into the next wave/swell, pitch can really suck! Though, on the flip side of the coin, roll empties shelves of supplies, even moderately weather-proofed shelves, all over the decks much quicker.

Quoting United Airline (Reply 16):

Quoting PPVRA (Reply 7):
Bigger will always help. Bigger + stabilizers even better.

How much of a difference between Grand Princess and Oceania Insignia at Cape Horn? It was really rough that time



Quoting United Airline (Reply 24):
Up and down is ok. But left and right bothers me

The last leg I was out (basically 4 of the last 5 weeks) I woke up several times from a dead sleep bracing myself and thinking rapidly about how I'd get out of the pitch black cabin I was in quickly and out onto deck if the roll I had woken up to continued what felt like only a few more degrees...though in reality it wasn't quite that bad, being in the trough of 8-10 ft swell on a 100' LOA mudboat makes you wonder every so often  Wink
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RE: How Do Stabilizers On Ships Work?

Fri Oct 31, 2008 9:08 pm



Quoting DocLightning (Reply 10):
I made the Drake Passage without getting sick. Second day of the voyage I felt a bit "off" but I was faring a lot better than many of the Russian crew

Another survivor of the 'Drake Shake', I did it in February of this year on the way down to Antarctica. Let that ship pitch all it wants, but the roll definitely had me feeling queasy, no problems when I could see outside though. The problem was in the halls and other areas you couldn't establish a point of reference.

On the way we hit a maximum roll on our trip of 60 degrees! Booya!
 
MarSciGuy
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RE: How Do Stabilizers On Ships Work?

Fri Oct 31, 2008 11:01 pm



Quoting C172Akula (Reply 33):

Quoting DocLightning (Reply 10):
I made the Drake Passage without getting sick. Second day of the voyage I felt a bit "off" but I was faring a lot better than many of the Russian crew

Another survivor of the 'Drake Shake', I did it in February of this year on the way down to Antarctica. Let that ship pitch all it wants, but the roll definitely had me feeling queasy, no problems when I could see outside though. The problem was in the halls and other areas you couldn't establish a point of reference.

On the way we hit a maximum roll on our trip of 60 degrees! Booya!

WOW!!!!!!!!!!!!!!!! 60 degrees! Why were you heading for Antarctica?
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MCOflyer
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RE: How Do Stabilizers On Ships Work?

Sat Nov 01, 2008 12:59 am



Quoting Zkpilot (Reply 31):

The bottom photo looks like 30ft swells. Nice photos.

If I ever own a a trawler, a Sea Gyro is going to be on order for stability. This is the stabilizer is for small craft unlike big ships we have shown. However, stabilizers don't jack for for big waves like 40ft-60ft.

Hunter
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