QE2's Stabilisers

[Rob Lightbody]

OK - Question.

If QE2 sailed WITHOUT deploying her stabilisers, in moderate seas (e.g. a typical transatlantic) would she be safe, or would the rolls actually be dangerous?  (Discounting passenger discomfort or furniture & fittings falling over I mean).

QM1 used to have fairly huge rolls at times... would QE2 do the same?

Assumption - having the stabilisers deployed reduces the efficiency of the ship because of the added drag (she uses more fuel for the same speed).

So - the reason for my question - if Nakheel are wanting to re-locate QE2 under her own steam with the minimum cost, would they be best off to tie everything down and not deploy the stabilisers?

[Twynkle]

Hi Rob
It'll be good to read the others' replies to your interesting question
Please excuse my lack of maritime / engineering knowledge here - and I could well be mistaken!

If the QE2 isn't being used for passenger and other services and she's is running with a skeleton crew,
there'd be no need for the 'normal' power out-put.
That is - for air con etc, waste disposal, galleys, stores, crew needs etc etc, meaning considerably reduced running costs.
Wouldn't she run on 'heavy / cheaper oil' and grey water in any case, for much of the time?

To reduce costs by possibly compromising stability, safety and efficacy -  mightn't this not only jeopardise any one, or all of the following:
 - her ability to sail at speed if and when necessary, possibly for meteorological / navigational /engineering / security reasons etc
 - Pose a risk to her need for security - vulnerability to piracy etc
 - Put at risk specific factors relating to her insurance cover?

Maybe some of the other UAE states could pitch in and help with bunkering!

Rosie   

 PS - there were rumours last year that one of her stabilisers wasn't working - not at all sure whether this was correct / not!
 

[StuM]

Rob, I traveled on her many times when the stabilizers were not used. Of course, normally in smooth to moderate seas. I recall, as I went to Maritime College and learned about ship stability, that I talked to one her junior officers one time about it. He said the calc's (center of gravity, metacentric height, GM, etc) were such that she was always stable, (assuming normal tank and ballast levels) and that the fins kept personnel comfort levels much higher. I took his comments to mean she would not become unstable without the fins out. recall also, that she has full bilge keels, thus also helping to dampen roll.
I also seem to recall several officers saying that the fins, while having some drag increase, were not as much of a speed detriment as one might think. They noted, that without the fins out, the rolling might be such that speed had to be reduced more in the base case.
 
I also recall a voyage on the original QE, where at least one of the stabilizers was not working, thus they only used one pair, at high speed. Those officers said they clearly felt the difference, whereas she was more or a roller than QE2. One funny final comment, I recall old Cunard folks saying, that even though the QM and QE's hulls at waterline and below, were essentially identical, that the Mary was by far the worse of the two, for original rolling. Even with the QE having the extra deck.
StuM

[skilly56]

Rob,
The comment above that they are for increased comfort of those aboard the ship is correct.

Lloyd's Register requirements would be that the ship must be able to handle ALL sea states WITHOUT the stabilizers, as in the event of multiple failures of said fins, the ship's safety must not be compromised. Ok, so it might get a little rougher for everyone, but a course alteration would reduce the ship's movements somewhat.
Last July, only 2 stabilizers were actually functional (port fwd & stbd aft if my memory is correct), but the voyage was so calm I don't think they were even used.

As the stabilizers are virtually useless at slow speeds, the ship would always have to be ballasted/trimmed to such a condition (i.e., have a GM between 1.36 and 1.44 m) that in the event of having to stop suddenly (ie, someone going overboard), the vessel's stability was not compromised by suddenly slowing down and losing the stabilizing effect of the fins.

Rosie, you have a pretty good handle on the systems loads involved for someone who professes to 'not be technically minded'. You should have been a marine engineer! As well as the drag on the fins, there is also the electrical load to drive the hydraulic pumps to supply the 'motive power' that actually drives the fins. In rough weather they are changing their angle of attack continuously, so the hydraulic loads are quite demanding.

Cheers
Skilly

[Rob Lightbody]

Thank you for such a complete answer to my discussion point !

I had guessed the answer, without knowing the 'ins and outs' of it.

Did the stabilisers stay faulty until Dubai or were they repaired?  My trip (mid-late August) involved some proper heavy seas in the Bay of Biscay, but the main sensation was pitching, rather than rolling as I recall...

[Bob C.]

Rob, with my extended time at sea I can tell you that the effectiveness of the stabiliers depends on sea state, sea direction (wave orientation to the ship - head-on, following, quartering, etc) and ship speed.  Skilly56 is absolutley correct that a passenger ship must be able to handle all seas without stabilizers and your assumption that is would be a bit more uncomfortable is spot on. 

The worst conditions I've encountered on an aircraft carrier (bilge keels, no stabilizers) are moderate sea states, medium period (about the ship's length between swells) and quartering seas (waves traveling with the ship off the port/stbd stern) at about 15-20 kts ship speed.  Sparing everyone the math, these types of seas harmonically roll and pitch a ship very uncomfortably and is where stabilizers can be used most effectively. 

However, a ship is designed to to take the rolls so that she can right herself safely.  The engineering term is called the "righting moment" which is the bouyancy force acting on the distance between the center of buoyancy (CB) and center of gravity (CG).  This website has a few good drawings to help explain the concept if anyone is interested (http://www.marineengineering.org.uk/navarch/navstability.htm). 

Bottom line:  Stabilizers augment the natural righting moment of the hull design for a more comfortable ride but are not necessary for safe stability.

[skilly56]

Hi There Bob C.
Had a little chuckle when I read your comment about aircraft carriers rolling. I suddenly realised that a lot of people on this forum don't really know what a big roll is like. After 5 years RNZNVR, I had 20 years at sea on bulk carriers - the last one was the final ship out of the Robb Caledon yard at Dundee. She had an 8 ft 6 inch GM when loaded, and 12 ft 6 inch in ballast - has a very shallow draught and broad beam. Don't know how I lasted 12 years on this beast (C/E), but could she ever roll! Naturally, no stabilizers, only bilge keels. She even rolls in the drydock (LOL)

Brisbane back to Nelson (NZ) was 101 hours on honeymoon revs (ie, the engineers were going home on leave and didn't want to miss the plane). The worst trip was 9 in ballast days of pounding, slamming, corkscrewing - punched up all the plating under the bow thruster tunnel and cracked all the bulwarks.
We took some office staff on one trip, then they all went missing - were found in their cabins, sitting on the deck, talking into their big white telephones! I was carried off this ship in 1990 with a smashed back - been ashore since. But obviously I haven't learn't much while ashore - I am rejoining this same ship on the 11th of next month! At 30 years old she is still going strong - they build'em good in Scotland!
Cheers
Skilly

[Rob Lightbody]

There are some photos on the net (and in books) of QM1 and Normandie with 40 degree rolls - definitely looked fun!

[Twynkle]

More about QE2's stabilisers.
"and are extended for most of the time when at sea."
"...damping the roll by as much as up to 60%."
"...When 'working' hard in rough seas they do cause a small amount of drag which can reduce the ship's speed by up to 1/2 kt."
From:  Peter Moxom (1990) 'From the Bridge: Cunard's Flagship'.

[Rob Lightbody]

Stabiliser control panel, seen during my recent visit to QE2 in Dubai.

[Twynkle]

What a good sight!

Rob - whereabouts was the panel situated in relation to the other controls?
It's so neat!
In the 60's it's design would have been like most other things on board - 'modern'
now (in comparison with the panels on QM2) it looks truly retro!

[skilly56]

Hi Rosie,

This panel was in the wheel house. There is another panel in the ECR console, but it doesn't have the over ride key function.

The key switch in the centre is usually to enable manual control of the stabilizers for testing purposes - turn it to the right and the stabilizers will roll the ship to Stbd and stay there until you use the key to bring it upright again. Turn the key to the left and ship will roll to Port.

Very good device for spilling drinks and clearing desks quickly!!

Cheers

Skilly

[Twynkle]

WOW  Skilly!

What power lay in the hands of those fortunate to be helmsmen/quartermaster - or would it be the lucky OOW, or maybe the Master even?
Do you think that the over-ride system was ever used at times other than for testing?
How often do/did the 'fins' require testing - possibly in different conditions perhaps?
And on from your explanation about the ECR missing out on having the facility to override the system - in terms of stability when underway, were there other mechanisms to do with keeping her true that were in the wheelhouse and yet not in the ECR?
Hope this isn't the wrong question to ask?!! 

(So I wonder now, does this answer the question about the little perspex box covering a little sort of mini-type of lever (not a key, if I remember correctly) in the central console, and very close to the stabiliser controls on the QM2?
Unfortunately (or otherwise !) i haven't yet had time to unpack - let alone look at any of the very many photos of the ship. Otherwise there's be a picture to illustrate what I mean...



Bit off topic here - hope Mods'll not mind!)

[Rob Lightbody]

Hi Rosie,
The key switch in the centre is usually to enable manual control of the stabilizers for testing purposes - turn it to the right and the stabilizers will roll the ship to Stbd and stay there until you use the key to bring it upright again. Turn the key to the left and ship will roll to Port.

Very good device for spilling drinks and clearing desks quickly!!

They did this in April 1987 when i was on board.  They introduced a major roll - and then activated the stabilisers again to cancel it out.  a warning was broadcast before they did it, but it still seemed fairly dramatic at the time!

[skilly56]

Rosie,

Your little 'mini-type' lever sounds like the combined thrust control lever for the bow thrusters. With 3 thrusters, you don't have time to control three separate levers, so the smart way is to control the thrust direction & power with one lever.

On most control systems, when switching between manoeuvring control stations (ie., Port Bridge Wing/Centre console/Stbd Bridge Wing), the control lever you are changing to needs to be at Zero Thrust or Pitch before control can be transferred and accepted at the new position. The little plastic box is to stop anybody accidently knocking the thrust lever off the Zero detent position and not realising they have done it.


Part 2 of the answer (Operating the Manual roll key) - this is definitely senior OOW territory and probably only after consultation with the master.

Sometimes we engineers need a degree of roll in a certain direction for an uninterrupted period - eg, to suck the last s.w. out of a ballast tank when the centre ballast suction valve may be faulty and you want to get the ballast water out to the wing tank suction foot to drain the tank completely. A phone call to the OOW, then use of the key, solves the problem. The engineers do not have the key panel in the ECR as they are not able to observe any other activity going on up top that may make create a dangerous situation when the ship was rolled.
 
Of course - this means of rolling the ship only works when the vessel is at sea and has good speed on. When stopped, the stabilizers are totally useless, and before entering port they have to be stowed into the hull to prevent them being damaged when coming alongside the wharf.

Cheers

Skilly