Topic: Stabilisers and cost of fuel

QUOTE:

That's exactly what a gyroscope would do, correct both roll and pitch.


Pete

Sorry Pete, but Gyro's won't correct the pitching.

Watched QM2 on Megaships last night. Even this technologically advanced leviathan with all of it's stabilisers engaged could only correct the rolling, but not the pitching.

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ILLEGITIMI NON CARBORUNDUM
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QUOTE:

When I went on Balmoral to the Canaries in May it was pretty smooth even in rough seas, and Capt Sovdsnes told me he had been using the stabilisers all the way, which surprised me a bit as I thought they would create drag and use a lot of fuel.

Anyone know if that is the case?

Also, last year on IoTS you would have been hard pressed to know you were on a ship unless you looked out of the window as it was very smooth.

However, in June it was very, very bumpy even in the same force winds and a lot of people said they felt sick (I didn't - £3.95 seabands from all good chemists). The only difference seemed to be that on the cruise before mine, the fixipod was damaged on a sandbank and had to be removed so we were travelling on azipods.

I wondered if this meant we couldn't use the stabilisers or is it just that the fixipod creates stability?

And another thing..... we had barely docked back at So'ton before Whitchallenger was alongside refuelling so I wondered how much fuel IoTS holds and if it's enough for a full two-week cruise? How many miles to the gallon for a 160,000 tonne ship?

Thanks in advance to anyone who knows the answers!
Liz
x

I understand that the azure does 60ft per gallon, or 94 gasllons per mile

QUOTE:

I understand that the azure does 60ft per gallon, or 94 gasllons per mile

liz,
Fixipod,this is a new one on me,ship propulsion comes in three basic forms,
1..sail
2 fixed props
3 variable pitch props
4 azimuth and azipod systems,the first three i have worked with and used ,but the mod azipod system is beyond my ken we would have to get an engineer to give us the word,and also advise on the extra fuel used when the stabs are out ,tho i suspect it is not much,we used to put the stabs out on the ferries at the slightest sea movement so as to ensure the safety of the cars/trucks and the comfort of the passengers.
i would think that cruise ships would carry about 20% extra fuel over and above what her consumption for the trip it is normal proceedure for a bunker barge to come a/l a ship as soon as she berts so as to get her tanks filled up ready for the next trip.

jim

QUOTE:

liz,
Fixipod,this is a new one on me,ship propulsion comes in three basic forms,
1..sail
2 fixed props
3 variable pitch props
4 azimuth and azipod systems,the first three i have worked with and used ,but the mod azipod system is beyond my ken we would have to get an engineer to give us the word,and also advise on the extra fuel used when the stabs are out ,tho i suspect it is not much,we used to put the stabs out on the ferries at the slightest sea movement so as to ensure the safety of the cars/trucks and the comfort of the passengers.
i would think that cruise ships would carry about 20% extra fuel over and above what her consumption for the trip it is normal proceedure for a bunker barge to come a/l a ship as soon as she berts so as to get her tanks filled up ready for the next trip.

jim

Thanks Jim, thought you might be interested in this link Search Propulsion - ABB Marine - Azipod® Propulsion Profile.

I've come to the conclusion that being captain is quite a difficult job because not only have you got to manouvre in shallow water but you've got to make sure you use the azipods to counter any tides and swell so you don't collide with the quay. I guess sandbanks shift as well so there's always a chance of a hidden object where you don't expect to find one.
Liz
x

QUOTE:

Thanks Jim, thought you might be interested in this link Search Propulsion - ABB Marine - Azipod® Propulsion Profile.

I've come to the conclusion that being captain is quite a difficult job because not only have you got to manoeuvre in shallow water but you've got to make sure you use the azipods to counter any tides and swell so you don't collide with the quay. I guess sandbanks shift as well so there's always a chance of a hidden object where you don't expect to find one.
Liz
x

Hello Liz,
Most ships if you look on the side will have a barge loading fuel into the ship during disembarkation time and sometimes in ports being visited which I've seen in Southampton and Victoria.
Also have depth sounding and sonar to confirm charts though in Victoria we have pilot boats that come along aside in the Straits.
I believe in earlier posts as to low sulphur or regular bunker oil it was identified that a 20% +- decrease in consumption was achieved in using Azipods.
What is remarkable about Azipods is their flexibility , ease of use and power to manouver a ship.
You are correct in of the difficulty one has in coming alongside a quay especially if tidal movements or sea swells are high.
At times a tugboat can be used though In Victoria we have had a few instances each year where the ship will not dock but remain outside the quay areas due to tide and wave movements.
Once the ship is committed to dock and goes very slow, its power is enough to move but not enough to move out fast if betwen two quays but I'm not an expert.

Last night on Discovery I watched a seqment on the largest ship in the world that layed pipe from a gas well to the shore in Norway.
Thsi ship had I believe 8 - 12 azipods to allow it to manouver by inches as they had to drop a continuous string of 24 metre section of pipes in a trench about 700 metres depth in the sea and by GPS they would manouver the ship that distance each time.
Remarkable.

QUOTE:

Hello Liz,
Most ships if you look on the side will have a barge loading fuel into the ship during disembarkation time and sometimes in ports being visited which I've seen in Southampton and Victoria.
Also have depth sounding and sonar to confirm charts though in Victoria we have pilot boats that come along aside in the Straits.
I believe in earlier posts as to low sulphur or regular bunker oil it was identified that a 20% +- decrease in consumption was achieved in using Azipods.
What is remarkable about Azipods is their flexibility , ease of use and power to manouver a ship.
You are correct in of the difficulty one has in coming alongside a quay especially if tidal movements or sea swells are high.
At times a tugboat can be used though In Victoria we have had a few instances each year where the ship will not dock but remain outside the quay areas due to tide and wave movements.
Once the ship is committed to dock and goes very slow, its power is enough to move but not enough to move out fast if betwen two quays but I'm not an expert.

Last night on Discovery I watched a seqment on the largest ship in the world that layed pipe from a gas well to the shore in Norway.
Thsi ship had I believe 8 - 12 azipods to allow it to manouver by inches as they had to drop a continuous string of 24 metre section of pipes in a trench about 700 metres depth in the sea and by GPS they would manouver the ship that distance each time.
Remarkable.

Very interesting Rob, thanks for that.
Liz
x

What a terrific thread

QUOTE:

In 1991 on a Carnival cruise we were told the ship was stabilised by using two very large, several tons each, gyroscopes spinning at very high speeds in opposite directions about a vertical axis. This allows free movement of the ship around the horizontal axis ie when turning, any movement in any other plane is counteracted by the gyroscope and therefore damped.
Any body else heard of this method of stabilisation?

Here's a link to wikipedia

Ship stability - Wikipedia, the free encyclopedia

I also saw a documentary saying exactly the same thing until then I always thought that stabilisers were 'wings' that were able to control the degree of a ship's roll? Plus they can also be retracted

This is a picture of just one of the stabilisers on the Queen Elizabeth

QUOTE:

If you are unfortunate and suffer from Mal de Mare, the most suitable accommodation is a lower deck inside cabin, amidships.
Oh and always have a bed laying fore & aft, not across the beam.

I am NOT saying you are wrong and this is me throwing my thoughts as a non-cruise person into the sea sick pot...

I guess that everyone I speak to have always stated that the smoothest place to be when encountering rough weather is amidships and amidships or as close to the middle of a ship as possible and as low down!

Okay I will put on my steel helmet and go completely out of kilter and maybe change World thinking on this suggestion, but PLEASE look on this as me asking a question as opposed to saying the whole world is wrong and I am right......

If we accept that a ship is quite a heavy object and in rough weather it is usually the front or bow of a ship that gets lifted by a wave or large swell then I will attempt to put my point across

The ship will get lifted by the wave, but as the vessel is lifted it is also cutting through this hunk of water and attempting to squash it (just by weight)

As the ship moves through the water it is lifted, but at the same time the wave is being flattened and with these large ships it is very, very, very rare that any ship will balance on the very top of a wave and rock at the centre point.. It just does not happen.

I am convinced that the wave is attempting to lift the ship and because this wave is being flattened then the fulcrum will be right at the very stern of the ship or as close as possible to it because yes.. yes the ship might ride over a wave, drop the bow right down and then lift the stern, but usually the ship is moving through the wave at speed, it is cutting through it, flattening it as it cuts though and by the time the wave has gone a third or half way down the ship, it has usually lost most of its energy? Remember any captain will do their best to steam around violent weather.

These are just my thoughts and I am throwing them into the pot for discussion... I am NOT saying I am right, I am saying.. How about this point of view.

Sea sickness is a genuine ailment and that is fact BUT... It can also be bought about by negative thoughts, so if folks believe that being in the centre of the ship is the best place, and that works, then so be it, what EVER works is always right, no matter what the science. By the way I have NO edukayshunnal qualiffikayshuns so apologies for the poor grammar and poor use of physics.


Thank you very much for posting the thread and is fuel consumption on ships usually discussed in tons\tonnes


Regards
John the inquisitive

QUOTE:

What a terrific thread



I also saw a documentary saying exactly the same thing until then I always thought that stabilisers were 'wings' that were able to control the degree of a ship's roll? Plus they can also be retracted

This is a picture of just one of the stabilisers on the Queen Elizabeth




I am NOT saying you are wrong and this is me throwing my thoughts as a non-cruise person into the sea sick pot...

I guess that everyone I speak to have always stated that the smoothest place to be when encountering rough weather is amidships and amidships or as close to the middle of a ship as possible and as low down!

Okay I will put on my steel helmet and go completely out of kilter and maybe change World thinking on this suggestion, but PLEASE look on this as me asking a question as opposed to saying the whole world is wrong and I am right......

If we accept that a ship is quite a heavy object and in rough weather it is usually the front or bow of a ship that gets lifted by a wave or large swell then I will attempt to put my point across

The ship will get lifted by the wave, but as the vessel is lifted it is also cutting through this hunk of water and attempting to squash it (just by weight)

As the ship moves through the water it is lifted, but at the same time the wave is being flattened and with these large ships it is very, very, very rare that any ship will balance on the very top of a wave and rock at the centre point.. It just does not happen.

I am convinced that the wave is attempting to lift the ship and because this wave is being flattened then the fulcrum will be right at the very stern of the ship or as close as possible to it because yes.. yes the ship might ride over a wave, drop the bow right down and then lift the stern, but usually the ship is moving through the wave at speed, it is cutting through it, flattening it as it cuts though and by the time the wave has gone a third or half way down the ship, it has usually lost most of its energy? Remember any captain will do their best to steam around violent weather.

These are just my thoughts and I am throwing them into the pot for discussion... I am NOT saying I am right, I am saying.. How about this point of view.

Sea sickness is a genuine ailment and that is fact BUT... It can also be bought about by negative thoughts, so if folks believe that being in the centre of the ship is the best place, and that works, then so be it, what EVER works is always right, no matter what the science. By the way I have NO edukayshunnal qualiffikayshuns so apologies for the poor grammar and poor use of physics.


Thank you very much for posting the thread and is fuel consumption on ships usually discussed in tons\tonnes


Regards
John the inquisitive

A very interesting theory,but to my mind completely wrong,I have spent a lifetime at sea and steamed thru many storms,and i can assure you that how a ship acts depende soley on the height and period of the wave and the power of the wave is certainly not lost by the time it reaches the stern,I would suggest that if you are interested you should arrange a visit to the national physical lab at teddington and see wave action as it happens.
reference the earlier quote on stabilisers ,I know that the large gyros were tried on a few pass ships in the 30s ,then came the flume system (of whick i have had experience and later the fin system ,again of which i have had a lot of experience,these fins ARE controlled by gyros ,but only very small units.

jim

QUOTE:

A very interesting theory,but to my mind completely wrong,I have spent a lifetime at sea and steamed thru many storms,and i can assure you that how a ship acts depende soley on the height and period of the wave and the power of the wave is certainly not lost by the time it reaches the stern,

Hi Jim,
I am not talking about small ships and my remarks would only apply to large heavier vessels and I would be very grateful if you could explain why I am completely wrong regarding large vessels. Note how I emphasis large vessels.

For any length of material to be stable at its central point, the fulcrum would need to be in the centre of that object and as far as I am aware waves are not seperated by huge distances

For the stern to lift into the air, the front of the ship must go down and to get that stern to rise the swinging fulcrum must be amidships like a see saw in a play ground and to have just one single wave travelling down the entire length of a BIG ship is a rare event and one that would probably have serious effects.

On smaller vessels it is quite common for the propellers to leave the water, but how often would that happen on large ships the size of the Queens are even larger tankers. I would suggest that if it were to happen it would probably be because of a large trough reaching the stern whilst the rest of the ship was being supported by larger waves.

I have NEVER been on a cruise in my life but I did serve 12 years on the grey funnel line (probably not as long as your very good self) but that was mainly on smaller vessels of approximately 2000 tons although I did serve for 12 months on one of just over 5000 and another 12 months on a 24000 ton vessel

I TOTALLY, 100% accept that smaller ships will possibly ride over waves like a cork, but I am not talking about small vessels.

I hope I have explained myself a little better and yes the stabilisers are no doubt operated by internal gyros.

Edit
Just noticed that you stated,

"the power of the wave is certainly not lost by the time it reaches the stern"

Hopefully I have NEVER suggested any such thing and I am certainly NOT implying that. I am simply saying that as a wave is travelling from frrd to aft attempting lift 90,000 tons of weight, this wave will gradually loose height as the ship rides over it.

Look over the stern of any ship and compare what is seen to that at the front that is just about to force itself upon the ship and you will see the difference (hopefully)

Watch the video link I have attached and see how the wave is spread by the bows as it hits the ship and also the water at the sides as the wave is dissipated.

QUOTE:

Hi Jim,
I am not talking about small ships and my remarks would only apply to large heavier vessels and I would be very grateful if you could explain why I am completely wrong regarding large vessels. Note how I emphasis large vessels.

For any length of material to be stable at its central point, the fulcrum would need to be in the centre of that object and as far as I am aware waves are not seperated by huge distances

For the stern to lift into the air, the front of the ship must go down and to get that stern to rise the swinging fulcrum must be amidships like a see saw in a play ground and to have just one single wave travelling down the entire length of a BIG ship is a rare event and one that would probably have serious effects.

On smaller vessels it is quite common for the propellers to leave the water, but how often would that happen on large ships the size of the Queens are even larger tankers. I would suggest that if it were to happen it would probably be because of a large trough reaching the stern whilst the rest of the ship was being supported by larger waves.

I have NEVER been on a cruise in my life but I did serve 12 years on the grey funnel line (probably not as long as your very good self) but that was mainly on smaller vessels of approximately 2000 tons although I did serve for 12 months on one of just over 5000 and another 12 months on a 24000 ton vessel

I TOTALLY, 100% accept that smaller ships will possibly ride over waves like a cork, but I am not talking about small vessels.

I hope I have explained myself a little better and yes the stabilisers are no doubt operated by internal gyros.

Edit
Just noticed that you stated,

"the power of the wave is certainly not lost by the time it reaches the stern"

Hopefully I have NEVER suggested any such thing and I am certainly NOT implying that. I am simply saying that as a wave is travelling from frrd to aft attempting lift 90,000 tons of weight, this wave will gradually loose height as the ship rides over it.

Look over the stern of any ship and compare what is seen to that at the front that is just about to force itself upon the ship and you will see the difference (hopefully)

Watch the video link I have attached and see how the wave is spread by the bows as it hits the ship and also the water at the sides as the wave is dissipated.

Hi,
Interesting to read of your theory and maritime history,but one question,are you an engineer?if so then your technical knowledge will probably be superior to mine,Studying for masters only involved basic engineering and ship construction and my ship experience whilst deep sea only involved 12000GRT ships,you talk of 90000 tonners2remember that is gross tonnage ,measured on cubic capacity and a 2000 pass cruise ship might only be about 35000 displacement.
i still adhere to my claim that it depends on the wave period whether a ship acts to one wave before another hits the bow.
I will speak to a friend who has just recently retired as master of a very large container ship and ask his views on wave action on a 800ft ship travelling at 20 knots .

jim