Is Oasis having stabilizer problems?

[The Sunset Glow]

I’ve heard a couple of people say on other forums that Oasis is having a stabilizer problem? Anyone on here know anything about this?

[chengkp75]

I haven't heard anything about Oasis, but many, many folks don't realize what stabilizers actually do and don't do, and think there is a problem. Stabilizers do not stop the ship from rolling. Stabilizers actually need some roll motion to operate, as they sense a roll starting and then react to the roll. Stabilizers are also not to reduce the amount of rolling, but to slow the rolling down to comfortable levels. Cruise ships, with their natural high center of gravity, tend to "snap roll" or roll very quickly from port to starboard. Stabilizers produce an anti-roll force that is "out of synch" with the rolling force, damping down the period of the roll, meaning it takes longer for the ship to roll from port to starboard and back, a more comfortable motion.

[Sitzmark]

maybe they need to turn them off and back on again.

[cingroomer]

I have heard that one is broke and last week on the ship it rolled gently but more than normal, it is still doing it this week according to some of my friends that are on there. It didn't seem to impact anyone was just odd to have a ship of that size roll like it did.

[Sotermarler]

What do they have to do to fix it? Or can they limp along until they dry dock next?

 

 

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[chengkp75]

Oasis, IIRC, has two sets of stabilizers, and if one is malfunctioning, she can operate quite well on just 3 fins. Norwegian Sky operated for 4.5 years with one fin removed. If there is a problem with the rotation mechanism or the seals, then it will require a drydock to repair.

 

And it is very hard to quantify how a ship is rolling from one voyage to the next, as things like ships speed, course (in relation to currents or seas), wave height and period, wind speed and direction, etc, will affect the ship differently, even in apparently similar conditions.

[Magnetchief]

What do they have to do to fix it? Or can they limp along until they dry dock next?

 

 

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Hopefully it's an internal hydraulic issue.

They can repair alongside or even at sea.

 

External will require a dry dock, or at least some sort of cofferdam, a pumped-out compartment secured to the ship.

 

But as noted, they should be fine with just 3 fins, just have towork harder.

I would not have thought the passengers would have noticed to behonest.

 

 

Now, the South Atlantic in a 3,500 ton Ship with just one stabilizer working. That is fun.

[steamboats]

In case they need a dry dock to fix it then they wait until next year for the already scheduled dry dock in Cadiz.

 

 

I don´t think the Oasis is using the stabalizers frequently in the Caribbean. With normal sea you don´t need them. In fact they´d cost you more fuel if you use them. So usually the captains only use them when it´s really rough.

 

 

steamboats

[chengkp75]

In case they need a dry dock to fix it then they wait until next year for the already scheduled dry dock in Cadiz.

 

 

I don´t think the Oasis is using the stabalizers frequently in the Caribbean. With normal sea you don´t need them. In fact they´d cost you more fuel if you use them. So usually the captains only use them when it´s really rough.

 

 

steamboats

 

They are also more effective the higher the speed of the ship. With the relatively short distances between ports in the Caribbean, the ships travel at lower speeds and the stabilizers are less effective, so less frequently deployed.

[JaniceB]

Good to have people in the know explain these things, I also read that they were having trouble with them. I wouldn't want to be in the Atlantic crossing without them.

[Pratique]

They are also more effective the higher the speed of the ship. With the relatively short distances between ports in the Caribbean, the ships travel at lower speeds and the stabilizers are less effective, so less frequently deployed.

 

We experienced this on Harmony between St. Thomas and San Juan. At eight knots with following seas the stabilizers seemed to make things worse (jolting motion). Captain Gus explained that it was tough to cancel out the motion but he tried his best.

[chengkp75]

We experienced this on Harmony between St. Thomas and San Juan. At eight knots with following seas the stabilizers seemed to make things worse (jolting motion). Captain Gus explained that it was tough to cancel out the motion but he tried his best.

 

Well, with predominately following seas, stabilizers won't do anything. They have no effect on pitching, or on slamming or jolting. This is a problem that all azipod equipped ships experience. The need for a large flat area of the hull above the azipods means that there is no reserve buoyancy in this area, so the hull will rise on a following sea more than a ship with a normal stern section and shafted propellers, though the "ducktail" that some ships add on tends to counteract this. Then as the stern rises on the sea, and the sea slides along the hull, it suddenly runs into the full bodied hull section forward of the azipods, and slams into this part of the hull, given the jarring motion noted. Following seas, with azipods also create a lot more course instability (the ship does not want to track on a steady course), and the azipods tend to sweep back and forth trying to correct the ship's course, and this can cause vibrations and "uncertain" rolling (rolls with hesitations) due to constant changes in how the following seas strike the stern of the ship.

[PCWalton1]

Thank you for an entertaining AND informative chat. I had a rudimentary understanding of how the stabilizers worked but this gave me much more clarity.

Much appreciated. :D

[Pratique]

Well, with predominately following seas, stabilizers won't do anything. They have no effect on pitching, or on slamming or jolting. This is a problem that all azipod equipped ships experience. The need for a large flat area of the hull above the azipods means that there is no reserve buoyancy in this area, so the hull will rise on a following sea more than a ship with a normal stern section and shafted propellers, though the "ducktail" that some ships add on tends to counteract this. Then as the stern rises on the sea, and the sea slides along the hull, it suddenly runs into the full bodied hull section forward of the azipods, and slams into this part of the hull, given the jarring motion noted. Following seas, with azipods also create a lot more course instability (the ship does not want to track on a steady course), and the azipods tend to sweep back and forth trying to correct the ship's course, and this can cause vibrations and "uncertain" rolling (rolls with hesitations) due to constant changes in how the following seas strike the stern of the ship.

 

 

 

Thanks for the detailed explanation, that seems to explain what we experienced. The captain later said he deployed the stabilizers but that they had limited effectiveness. The jolting was quite harsh that night. Like being in a small sailboat pushed by the waves rather than the wind.

 

 

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[The Fun Researcher]

Thank you chengkp75for all of the fantastic information!

 

I've always found it interesting how long it takes for a cruise ship to roll one way then the other. I especially notice this when seated next to a window in the MDR. The desire to have stabilizers to extend the period (duration between rolls) makes sense for the comfort of those on board.

 

If the stabilizers provide an opposing force to the roll in order to lengthen the period, it seems as though they would have to reduce the roll to some (maybe small) degree as well?

 

Dan

[gadaboutgal]

Seriously doubt any reports of problems regarding Oasis' stabilizer. We have been on the ship for the last 16 days and have experienced no issues.

[chengkp75]

Thank you chengkp75for all of the fantastic information!

 

I've always found it interesting how long it takes for a cruise ship to roll one way then the other. I especially notice this when seated next to a window in the MDR. The desire to have stabilizers to extend the period (duration between rolls) makes sense for the comfort of those on board.

 

If the stabilizers provide an opposing force to the roll in order to lengthen the period, it seems as though they would have to reduce the roll to some (maybe small) degree as well?

 

Dan

 

You are correct, though the amount of roll reduction is very small. The main force in determining how far the ship rolls is the force applied to the ship by the seas and the initial stability of the ship (basically the vertical distance between the center of gravity and the center of buoyancy. The force generated by the hundreds of tons of ship moving, is far more than can be generated by the relatively small stabilizer fins and their hydraulics. A small amplitude force applied at a different angle to the large amplitude force of the ship rolling will significantly extend the period of the roll.

[The Fun Researcher]

You are correct, though the amount of roll reduction is very small. The main force in determining how far the ship rolls is the force applied to the ship by the seas and the initial stability of the ship (basically the vertical distance between the center of gravity and the center of buoyancy. The force generated by the hundreds of tons of ship moving, is far more than can be generated by the relatively small stabilizer fins and their hydraulics. A small amplitude force applied at a different angle to the large amplitude force of the ship rolling will significantly extend the period of the roll.

 

Great info thanks.

 

 

Dan