Are there stabilizers on all RC and Celebrity ships?

[DJLDRUMS]

Do all RC and Celebrity ships have stabilizers installed while being built? Using them may be another story.Just wondering....

[nhraformula00]

I believe they all do. That is why they sail so smooth now a days. Back 40 years ago ships used to tilt back and forth, also for and aft. I remember watching the water at dinner in a glass move around. The last 15 years or so with a lot of ships being so huge, you barely feel any motion at all. At least I don't. We have been sailing Oasis class the last 10 years and never feel any movement. Hope this helps.

[smokeybandit]

Yes, though stabilizers don't guarantee a smooth ride and don't work for the "up and down" rocking, only "side to side" rocking.

[DJLDRUMS]

2 hours ago, nhraformula00 said:

I believe they all do. That is why they sail so smooth now a days. Back 40 years ago ships used to tilt back and forth, also for and aft. I remember watching the water at dinner in a glass move around. The last 15 years or so with a lot of ships being so huge, you barely feel any motion at all. At least I don't. We have been sailing Oasis class the last 10 years and never feel any movement. Hope this helps.

Interesting bit of information. I was told by a bridge officer a few years ago on an Oasis Class that they don't like to use them unless it's absolutely necessary because they have to go slower and burn more fuel, if that makes any sense?

[chengkp75]

Stabilizers are almost standard on cruise ships, and certainly on larger ones like RCI and Celebrity.  Use of stabilizers does require more fuel, as they increase the drag of the hull through the water.  However, the ship does not need to go slower to use stabilizers, quite the opposite.  A fin stabilizer works just like an airplane aileron, and the faster the ship moves through the water, the more effect the stabilizer has.  In fact, stabilizers lose all effectiveness at speeds of less than 6 knots, and most are designed to self-retract at this speed, mainly as a safety feature in case someone forgot to retract the fins while docking (fins have been ripped off the ship while docking).

 

Now, as to what stabilizers do.  They have absolutely no effect on pitching motion (the "up and down motion in the fore and aft direction).  They will not stop, nor seriously reduce rolling.  You would need an enormous fin, an enormous hydraulic system, and an incredibly strong attachment point to resist the rolling motion of something that weighs a hundred thousand tons.  In fact, a fin stabilizer requires the ship to be rolling before it can activate.  The stabilizer senses the ship rolling one direction, and induces a small force in the opposite direction.  This counter-force is out of sequence to the ship's rolling motion, so while it doesn't stop the ship from rolling, it slows the speed of the roll (time from one end of the roll to the other), making for a more comfortable rolling motion.

 

Cruise ships, with their high center of gravity, are known as "stiff ships" that will roll easily, but also generate tremendous forces to counter the rolling force, resulting in very quick motion from one side to the other ("snap rolling"), which is very uncomfortable.  Stabilizers, by adding their small counter-force out of synch with the roll, simulate a "tender ship" (one that rolls more slowly from side to side), making the rolling more comfortable. 

[DJLDRUMS]

5 hours ago, chengkp75 said:

Stabilizers are almost standard on cruise ships, and certainly on larger ones like RCI and Celebrity.  Use of stabilizers does require more fuel, as they increase the drag of the hull through the water.  However, the ship does not need to go slower to use stabilizers, quite the opposite.  A fin stabilizer works just like an airplane aileron, and the faster the ship moves through the water, the more effect the stabilizer has.  In fact, stabilizers lose all effectiveness at speeds of less than 6 knots, and most are designed to self-retract at this speed, mainly as a safety feature in case someone forgot to retract the fins while docking (fins have been ripped off the ship while docking).

 

Now, as to what stabilizers do.  They have absolutely no effect on pitching motion (the "up and down motion in the fore and aft direction).  They will not stop, nor seriously reduce rolling.  You would need an enormous fin, an enormous hydraulic system, and an incredibly strong attachment point to resist the rolling motion of something that weighs a hundred thousand tons.  In fact, a fin stabilizer requires the ship to be rolling before it can activate.  The stabilizer senses the ship rolling one direction, and induces a small force in the opposite direction.  This counter-force is out of sequence to the ship's rolling motion, so while it doesn't stop the ship from rolling, it slows the speed of the roll (time from one end of the roll to the other), making for a more comfortable rolling motion.

 

Cruise ships, with their high center of gravity, are known as "stiff ships" that will roll easily, but also generate tremendous forces to counter the rolling force, resulting in very quick motion from one side to the other ("snap rolling"), which is very uncomfortable.  Stabilizers, by adding their small counter-force out of synch with the roll, simulate a "tender ship" (one that rolls more slowly from side to side), making the rolling more comfortable. 

THANK YOU chengkp75 ! You've brought a new meaning to the word stabilizer. Your full and in depth account of these cruise ship items was a full lesson in itself. With your Merchant Marine credentials I along with other readers fully understand and appreciate you weighing in on my question. You've personally studied the sea in good and bad times. 

[gmerick]

Look for this symbol painted mid-ship just above the waterline:

The symbol marks the location of the stabilizer.

[chengkp75]

Some ships utilize two sets of fins.

[DJLDRUMS]

44 minutes ago, gmerick said:

Look for this symbol painted mid-ship just above the waterline:

The symbol marks the location of the stabilizer.

THANKS gmerick ! Good to know where to look now. Any idea just how far down from the water line that the stabilizer is located? In clear water is that opening visible?

[DJLDRUMS]

34 minutes ago, chengkp75 said:

Some ships utilize two sets of fins.

That's even more interesting, would that be based upon the size or tonnage of those ships? What's your thoughts on the Oasis or Icon class ships/ One or two fins?

[chengkp75]

17 minutes ago, DJLDRUMS said:

That's even more interesting, would that be based upon the size or tonnage of those ships? What's your thoughts on the Oasis or Icon class ships/ One or two fins?

Size is certainly a determinant of how many fins the ship has, but it can also be based on the calculated stability (i.e. roll period) of the ship.  Even small ships like NCL's Norwegian Sky can have 4 fins.  All of RCI's ships from Voyager onwards have 4 fins.

 

21 minutes ago, DJLDRUMS said:

THANKS gmerick ! Good to know where to look now. Any idea just how far down from the water line that the stabilizer is located? In clear water is that opening visible?

The fin would be located just above the turn of the hull from bottom to side, just above the double bottom, so somewhere between 6 to 7 meters (20-23 feet) below the waterline.  It would need to be exceptionally clear water, and you are looking almost straight down when standing on the dock (not to mention the shade thrown by the ship), and the slot is basically filled with the fin when retracted, so it would generally show as a "shadow" or "dark spot" on the side of the hull.

[DJLDRUMS]

7 minutes ago, chengkp75 said:

Size is certainly a determinant of how many fins the ship has, but it can also be based on the calculated stability (i.e. roll period) of the ship.  Even small ships like NCL's Norwegian Sky can have 4 fins.  All of RCI's ships from Voyager onwards have 4 fins.

 

The fin would be located just above the turn of the hull from bottom to side, just above the double bottom, so somewhere between 6 to 7 meters (20-23 feet) below the waterline.  It would need to be exceptionally clear water, and you are looking almost straight down when standing on the dock (not to mention the shade thrown by the ship), and the slot is basically filled with the fin when retracted, so it would generally show as a "shadow" or "dark spot" on the side of the hull.

Once again chengkp75 I thank you for your interesting information. I'm sure there are cruisers that will find your information positive as much as I do. I had no idea whatsoever that those class ships on up had four fins. Is that the maximum even as large as the Icon? Do mega size cargo ships have fins?

[chengkp75]

9 minutes ago, DJLDRUMS said:

Do mega size cargo ships have fins?

Cargo ships do not use stabilizers, though some will have roll stabilizing ballast tanks.  These are U-shaped water tanks that have controls to allow the water (a weight) to slosh back and forth side to side, again out of sequence with the ship's roll, to slow the roll down.

 

Those of us who've worked both passenger and cargo ships refer to passengers as "the cargo that complains".  Containers full of TV's, new cars, or tanks of crude oil don't complain if the roll is quick or jerky, so no need for stabilizers.  Also, cargo ships have way more weight down low, most of it at or below the waterline, they are much more "tender" than cruise ships, so their natural roll characteristic is much more comfortable than a cruise ship.  To give an example, I'll use the largest cargo ship every built, the Seawise Giant.  This bulk carrier, when fully loaded, was 24.5 meters under the water, and only about 5 meters from the water to the deck (top of the holds).  So, she was 83% under water.  At this draft, she would be carrying the weight (displacement not Gross Tonnage, which is volume, not weight) of 5.5 Oasis of the Seas.