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QM2 Propulsion Issues?

Underwatr

By Underwatr,
in Cunard Line

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babine

babine

Posted
Posted

Whether it be for interest alone, or concern about an upcoming sailing, people have their own reasons for asking. If you don't find the information from on board to be of use to you then don't read the thread. There is no harm in those who are following along on an issue to gather whatever information they can from whatever sources they wish. Criticizing them for doing so serves no purpose at all.

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rrunner

rrunner

Posted
Posted
I really think some people are overreacting to the questions posed by those of us who will be on the next sailing. The heading of this thread suggested that there could be issues and naturally some of us would initially be concerned. I'm sure most of us also realize that if there was a genuine problem Cunard would contact us.

 

Please don't jump down our throats because we are asking for information.

 

Thank you for saying that. I did call Cunard today - they were not aware of any problem with QM2. However - they told me supervisor's do not work on Sunday's so suggested calling back tomorrow.

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Winchester Ranger

Winchester Ranger

Posted
Posted
I really think some people are overreacting to the questions posed by those of us who will be on the next sailing. The heading of this thread suggested that there could be issues and naturally some of us would initially be concerned. I'm sure most of us also realize that if there was a genuine problem Cunard would contact us.

 

Please don't jump down our throats because we are asking for information.

 

A voice of reason.

 

It seems I do owe you that Champagne after all babs.

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balf

balf

Posted
Posted

 

 

Since I started the thread it has become apparent that the ship is capable of making way to maintain schedule between ports but the question of maneuvering remains, at least to me.

 

 

There is no problem with manoeuvring, if she needs tug assistance she will be in the same position as other many ships. In many ports tugs are still on standby anyway, though seldom actually used when she is docking or leaving.

 

I have also sailed aboard when she was a pod missing. There was no apparent difference in her performance.

 

David.

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Salacia

Salacia

Posted
Posted (edited)
My prediction? This will all shortly be much ado about nothing, and the next voyage will take place as scheduled. If I were on that voyage, I would only be interested, not concerned, worried, or anything of the kind.

 

Right now I am more interested in why people are so concerned about what is in the big scheme of things hardly worth the time of day to write about.

 

She's run on 3 pods before, even with one removed from her.

 

Don't sell QM2 short as to what she can do, and she doesn't need to do much considering these lethargic speeds she runs at on most of her voyages.

 

Sorry folks, but many of you are just not grasping me on this.

 

I think I understand what you and others are saying: QM2 works just fine on 3 pods - no problem.

 

But what I'm having a problem understanding is why the itinerary on this cruise was changed to an over-night in Tortola in an effort to repair the pod and why it was necessary for a second attempt at repair (reportedly successful) made by having GE repair crew meet the ship at sea to fix the pod if it didn't present any problem ...why not just wait until the ship docked in NY on Wednesday and fix the pod then rather than going to all that extra expense and inconvenience ? (Forgive me if that is a stupid question - I'm just trying to understand.) Thanks, -S.

Edited by Salacia
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laktex

laktex

Posted
Posted
I think I understand what you and others are saying: QM2 works just fine on 3 pods - no problem.

 

But what I'm having a problem understanding is why the itinerary on this cruise was changed to an over-night in Tortola in an effort to repair the pod and why it was necessary for a second attempt at repair (reportedly successful) made by having GE repair crew meet the ship at sea to fix the pod if it didn't present any problem ...why not just wait until the ship docked in NY on Wednesday and fix the pod then rather than going to all that extra expense and inconvenience ? (Forgive me if that is a stupid question - I'm just trying to understand.) Thanks, -S.

 

I suppose it may give them the (important?) opportunity to test the repairs under operating conditions.

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orvil

orvil

Posted
Posted

We were aboard QM2 on a TA crossing when she experienced a propulsion problem. It was a January eastbound crossing. We had left New York a few hours late due to a nor'easter. This incident occurred the day after we passed the Titanic point on the moving map. So, the Titanic was on my mind.

 

Something awoke me at about 2 in the morning. I woke my husband up and said, "The ship isn't moving." He said, "Don't be silly. We are still moving, just very slowly." He's an airline captain, so don't expect him to get very excited about much.

 

The television monitor showed that she had slowed from around 19 kts to 10 kts. We had just enough forward momentum to keep us from wallowing. A few moments later I heard a young voice on the PA in the hallway. I leapt out of bed, ran to the door, felt the door for fire and cracked the door open. The young man's voice was calling, "All hands to the ECR. All hands to the ECR." Silence thereafter.

 

I got back into bed. My husband and I lay there trying to figure out what ECR meant. We couldn't figure it out, but it kept us occupied. My husband said, "Don't worry. It's not serious until we hear from the Commodore." Okay, so we waited. Then, the PA crackled into the stillness, "All hands to the ECR. All hands to the ECR." It was the Commodore! So, I turn to my husband and said "What now, smart ass?" Can you tell we have been married a while? He said, we wait.

 

Maybe an hour later we hear the Commodore again. He said, "Stand down." Whew, problem solved. Now we want to know what ECR meant.

 

The next morning we asked every crew member we encountered about the event. No one was spilling the beans. We finally got an answer from Osman, the Maître's D in the QG. It was a propulsion problem.

 

The Commodore did address the issue in the noon address. He said that it was a propulsion issue. He went on to say that it is always better to gather the entire team to deal with an issue from the onset than have to assemble a team piecemeal as conditions worsen. He also said that we would be increasing our speed to make up for the lost time. He pushed the pods up to around 25 or 26 kts. That is not the QM2's maximum speed. But, it's really fast compared to a cruise ship. They only had to make up a couple of hours. With the increased speed, we couldn't detect any difference except on the television monitor.

 

BTW, ECR stood for Engine Control Room. Mystery solved.

 

The QM2 is an amazing piece of technology. On a good day, everyone should go up on deck to "Prophenge" and have their picture taken with the prop array. It gives you an appreciation of the engineering.

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jimmybean

jimmybean

Posted
Posted
We were aboard QM2 on a TA crossing when she experienced a propulsion problem. It was a January eastbound crossing. We had left New York a few hours late due to a nor'easter. This incident occurred the day after we passed the Titanic point on the moving map. So, the Titanic was on my mind.

 

Something awoke me at about 2 in the morning. I woke my husband up and said, "The ship isn't moving." He said, "Don't be silly. We are still moving, just very slowly." He's an airline captain, so don't expect him to get very excited about much.

 

The television monitor showed that she had slowed from around 19 kts to 10 kts. We had just enough forward momentum to keep us from wallowing. A few moments later I heard a young voice on the PA in the hallway. I leapt out of bed, ran to the door, felt the door for fire and cracked the door open. The young man's voice was calling, "All hands to the ECR. All hands to the ECR." Silence thereafter.

 

I got back into bed. My husband and I lay there trying to figure out what ECR meant. We couldn't figure it out, but it kept us occupied. My husband said, "Don't worry. It's not serious until we hear from the Commodore." Okay, so we waited. Then, the PA crackled into the stillness, "All hands to the ECR. All hands to the ECR." It was the Commodore! So, I turn to my husband and said "What now, smart ass?" Can you tell we have been married a while? He said, we wait.

 

Maybe an hour later we hear the Commodore again. He said, "Stand down." Whew, problem solved. Now we want to know what ECR meant.

 

The next morning we asked every crew member we encountered about the event. No one was spilling the beans. We finally got an answer from Osman, the Maître's D in the QG. It was a propulsion problem.

 

The Commodore did address the issue in the noon address. He said that it was a propulsion issue. He went on to say that it is always better to gather the entire team to deal with an issue from the onset than have to assemble a team piecemeal as conditions worsen. He also said that we would be increasing our speed to make up for the lost time. He pushed the pods up to around 25 or 26 kts. That is not the QM2's maximum speed. But, it's really fast compared to a cruise ship. They only had to make up a couple of hours. With the increased speed, we couldn't detect any difference except on the television monitor.

 

BTW, ECR stood for Engine Control Room. Mystery solved.

 

The QM2 is an amazing piece of technology. On a good day, everyone should go up on deck to "Prophenge" and have their picture taken with the prop array. It gives you an appreciation of the engineering.

 

I "knew" there would be a happy-ending, but what a gripping story, nonetheless! Thank you for sharing!

 

She is a wonderful, amazing ship! But, even with that realization, any trouble in the middle of the ocean, does get one's attention.

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chengkp75

chengkp75

Posted
Posted
If GE was called upon, it doesn't sound like a pod problem - they are Rolls Royce Mermaids. Seems more like a turbine or electrical generation/distribution problem.

 

Most likely not a gas turbine problem, but it may be in the thyristor drive that drives the pod motors at variable speed. The thyristors or transformers are what caused the fire before.

 

As for all the talk of problems with the loss of one pod, here's some facts.

 

With the loss of one azipod, the steering redundancy is reduced, but the ship's docking capability is in no way reduced. The stern thrusters that the azipods replace are about 1Mw each, usually 3-4 of them, so 4Mw total. The one steerable pod that would be used (if one is down), is 21.5Mw, or 5 times the power of the thrusters it replaced.

 

The fact that the ship could make 27 out of 29 knots (93% speed) using 75% of propulsion power shows how much energy and fuel it takes to get that last knot of speed.

 

The statement about the benefit of four pods over two pods is not quite correct. If a ship has two pods, the two can provide power in any direction, and the computer will adjust the speed and direction of the pod to provide both fore/aft and side to side motion at the same time. You don't need to keep one fore/aft and steer with only one.

 

One reason that they flew the GE reps out to the ship is that when the ship enters US waters, the USCG will require a tug escort from Ambrose lightship all the way to and from the dock. This is because ships have to have two steering units, and with one azipod out, there is only one steering unit.

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Salacia

Salacia

Posted
Posted
If GE was called upon, it doesn't sound like a pod problem - they are Rolls Royce Mermaids. Seems more like a turbine or electrical generation/distribution problem.

 

So it would seem since two General Electric LM2500+ gas turbines generate electricity...[Reference: http://www.cunard.com/documents/press%20kits/queen%20mary%202/queen_mary_2_technical.pdf]

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Salacia

Salacia

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Posted
The turbines aren't often used. The fuel is much more expensive than the diesels.

 

"...The two General Electric LM2500+ gas turbines will generate 25MW of electricity each, which is equivalent to 81,000 shp. They run at 3,600 rpm and turn a generator through a reduction gearbox. The turbines burn marine gas fuel oil and are generally only run when the ship needs to achieve higher speeds..." copied from http://www.cunard.com/documents/press%20kits/queen%20mary%202/queen_mary_2_technical.pdf

 

Considering that QM2 rarely if ever goes at higher speeds these days , no one is surprised that the turbines are not often used. But it's nice to think that those turbines could be operational, should the need arise - after all, that's the way the ship (the last ocean liner?) was built.

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Salacia

Salacia

Posted
Posted (edited)
Most likely not a gas turbine problem, but it may be in the thyristor drive that drives the pod motors at variable speed. The thyristors or transformers are what caused the fire before.

 

As for all the talk of problems with the loss of one pod, here's some facts.

 

With the loss of one azipod, the steering redundancy is reduced, but the ship's docking capability is in no way reduced. The stern thrusters that the azipods replace are about 1Mw each, usually 3-4 of them, so 4Mw total. The one steerable pod that would be used (if one is down), is 21.5Mw, or 5 times the power of the thrusters it replaced.

 

The fact that the ship could make 27 out of 29 knots (93% speed) using 75% of propulsion power shows how much energy and fuel it takes to get that last knot of speed.

 

The statement about the benefit of four pods over two pods is not quite correct. If a ship has two pods, the two can provide power in any direction, and the computer will adjust the speed and direction of the pod to provide both fore/aft and side to side motion at the same time. You don't need to keep one fore/aft and steer with only one.

 

One reason that they flew the GE reps out to the ship is that when the ship enters US waters, the USCG will require a tug escort from Ambrose lightship all the way to and from the dock. This is because ships have to have two steering units, and with one azipod out, there is only one steering unit.

 

My understanding is that the QM2 is equipped with Rolls Royce "Mermaid Pods", not ABB manufactured "Azipods".

 

I seem to remember that every time I was on QM2 as she approached NY Harbor to dock, there were tugs standing by even when all pods were functional. But I'll pay more attention when QM2 enters the harbor in a few hours :)

 

BTW, you wrote that the stern thrusters were replaced (The stern thrusters that the azipods replace are about 1Mw each, usually 3-4 of them, so 4Mw total. The one steerable pod that would be used (if one is down), is 21.5Mw, or 5 times the power of the thrusters it replaced...) but Cunard claims Queen Mary 2 has three thrusters of 3.2 MW each allowing the ship to turn in her own length in port without the use of tugs. These operate with a fingertip touch by an officer on the Bridge..." - copied from http://www.cunard.com/documents/press%20kits/queen%20mary%202/queen_mary_2_technical.pdf

Edited by Salacia
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chengkp75

chengkp75

Posted
Posted

Yes, the gas turbines will only be used when steaming at high speed. But remember, that within 200 miles of the North American coastline, that the diesels will be burning marine gas oil (what is called #2 diesel or home heating oil in the US) even in the diesels. So, the fuel saving is negated at that point, and one turbine generates as much power as 1.5 diesels, so there would be some combination of propulsion and hotel power that could benefit from a combination of turbine and diesel at less than full speed, since both gas turbines and diesels are more efficient when running at full load.

 

Azipod, while trademarked, is an industry generic term for a steerable pod, as opposed to a "fixipod" or non-steerable pod. It is easier to refer to an azipod than a "Mermaid azimuthing propulsion pod".

 

In many ports, port regulations require tugs to be in standby, whether used or not, while docking. Sometimes it depends on what dock is being used, the weather, and the ship's size. What I am referring to, is whenever a ship reports to the USCG, upon entering US waters, that there is a failure of any part of the ship's steering, the USCG will require an escort tug from the start of the NY harbor traffic separation scheme (site of the old Ambrose light) which is a couple of hours outside the Verrazano narrows, all the way to the dock. This is to be able to steer the vessel using the tug, should the remaining steering unit fail.

 

I've actually stood and worked inside thruster tunnels similar to those shown as the "big round holes", so I'm probably far more familiar with them than you.

 

You will note that I stated, and you requoted me as referring to "stern thrusters", not "bow thrusters". This is because prior to azipods, or Mermaid azimuthing pods, ships had both bow and stern thrusters. One of the advantages of using azimuthing propulsion pods over conventional shaft, propeller and rudder design, is that instead of needing the propeller shafts, the propellers, the rudders, and the stern thrusters required for docking, you only need the azimuthing pods, so ships with pods do not have stern thrusters (the pods replaced the stern thrusters, as I said). Without either stern thrusters, or azimuthing pods to provide lateral thrust at the stern, the bow thrusters will not allow the ship to spin 360* in its own length. It requires lateral thrust in one direction at the bow, and lateral thrust in the other direction in the stern, which makes the ship rotate around an axis that is midships. Without lateral thrust at the stern, the bow thrusters will turn the ship, but the axis of rotation will move almost to the stern, doubling the turning circle.

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