Millennium ships (in general), lacking thruster power?

[Tom-n-Cheryl]

I started THIS thread when high winds caused the Constellation to get "stuck" at the dock in Key West in 2012.

 

Now I see that the Infinity slammed into the dock in Ketchikan - presumably due to, in part, the inability to contend with the force of the wind.

 

What do you folks think... bad luck ? Lacking adequate thruster power? Captains pressured into situations where they get into trouble?

 

Thoughts?

 

Tom

Edited June 4, 2016 by Tom-n-Cheryl

[Tangocherie]

Tom,

 

With those gas turbine engines, I'm sure these ships have plenty power including the bow thrusters. Don't know what happened to Infinity in Ketchikan, but at least it seems no one was hurt!

[Tom-n-Cheryl]

"low energy" thrusters relative to the ship.... yep :)

 

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[Quo Vadis?]

 

What do you folks think... bad luck ? Lacking adequate thruster power?

Thoughts?

 

Tom

 

It happens when one gets older...

[jayoldschool]

They haven't used gas turbines for years. Connie actually has one of them on display in one of the boarding areas on deck 2.

 

Tom,

 

With those gas turbine engines, I'm sure these ships have plenty power including the bow thrusters. Don't know what happened to Infinity in Ketchikan, but at least it seems no one was hurt!

[Tom-n-Cheryl]

"low energy" thrusters relative to the ship.... yep :)

 

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Touché [emoji5]

It happens when one gets older...

 

 

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[Tangocherie]

They haven't used gas turbines for years. Connie actually has one of them on display in one of the boarding areas on deck 2.

 

 

That is not a display. It is a spare gas turbine engine which is available if an engine must be replaced. All Millenium Class ships are gas turbine powered. These power plants generate electricity which powers the thrusters and azipods and furnishes all electrical power to the ship. Look it up on Wikipedia.

Edited June 4, 2016 by Tangocherie

[dkjretired]

Not enough information for anyone on this board to make an educated reply.

[Wiltonian]

That is not a display. It is a spare gas turbine engine which is available if an engine must be replaced. All Millenium Class ships are gas turbine powered. These power plants generate electricity which powers the thrusters and azipods and furnishes all electrical power to the ship. Look it up on Wikipedia.

 

You mean all the references to diesel engines driving generators? Gas turbines run on very light high quality fuel - the precise opposite of the heavy dirty stuff general used by cruise ships.

 

Stuart

[Tangocherie]

You mean all the references to diesel engines driving generators? Gas turbines run on very light high quality fuel - the precise opposite of the heavy dirty stuff general used by cruise ships.

 

Stuart

 

Precisely...

[foodsvcmgr]

Supplementary Diesel engines were retrofitted to this class of ship and are now used most of the time, the gas turbines are only used when extra speed is required. This is due to the higher cost fuel needed.

I do not have any specs to compare if the thrusters on these ships are weaker than those of other modern cruise ships.

However I was on Celebrity Summit May 1 cruise to Bermuda and observed the extreme difficulty the ship experienced pulling away from the pier with all thrusters churning full force and a tug struggling to pull the bow. Admittedly high winds and an approaching storm but I have seen many other ships have much less difficulty in worse weather.

So to answer the question, yes I believe these ships have some sort of issue.

[Tangocherie]

Supplementary Diesel engines were retrofitted to this class of ship and are now used most of the time, the gas turbines are only used when extra speed is required. This is due to the higher cost fuel needed.

I do not have any specs to compare if the thrusters on these ships are weaker than those of other modern cruise ships.

However I was on Celebrity Summit May 1 cruise to Bermuda and observed the extreme difficulty the ship experienced pulling away from the pier with all thrusters churning full force and a tug struggling to pull the bow. Admittedly high winds and an approaching storm but I have seen many other ships have much less difficulty in worse weather.

So to answer the question, yes I believe these ships have some sort of issue.

 

So sorry,you are mistaken. Diesel supplemetary engines are used while the ships are in port for the sole purpose of Hotel electricity needs. All propulsion needs are furnished by power generated by the gas turbine engines. Please read the Wiki...i

Edited June 5, 2016 by Tangocherie

[jayoldschool]

Hate to tell you, you're the one that is mistaken. The turbines aren't used in regular operation, they consume too much fuel. You do know that Wikipedia is not an accurate source of information, right?

 

Right from wiki:

 

In 2007, she was refitted with the addition of a diesel engine as a fuel-saving measure.[3] The ship can run on any combination of the gas turbines or diesel.

 

If it's cheaper to run on diesel... what do you think they use?

Edited June 5, 2016 by jayoldschool

[spirit28]

Low power, or lack of judgement?

 

https://www.youtube.com/watch?v=ehxiSLzP7Lc

[LabGuy64]

Very true........not that it will stop anyone from giving their opinion.

 

 

 

 

Not enough information for anyone on this board to make an educated reply.

[Wiltonian]

You mean all the references to diesel engines driving generators? Gas turbines run on very light high quality fuel - the precise opposite of the heavy dirty stuff general used by cruise ships.

 

Stuart

 

The reality of cruise ship propulsion seems to be somewhat complex! Diesel generation using dirty cheap fuel seems dominant. However, concerns over sulphuric and other emissions nearer land have forced alternatives in some jurisdictions. Hence, many ships use a mixture. This article illustrates it perfectly, being about gas turbine installation, but the three ships mentioned have different combinations of generating equipment. Almost universally, the actual motive force is provided by electric motors,

 

http://www.geaviation.com/press/marine/marine_2003812.html

 

Stuart

[BillB48]

Hate to tell you, you're the one that is mistaken. The turbines aren't used in regular operation, they consume too much fuel. You do know that Wikipedia is not an accurate source of information, right?

 

Right from wiki:

 

In 2007, she was refitted with the addition of a diesel engine as a fuel-saving measure.[3] The ship can run on any combination of the gas turbines or diesel.

 

If it's cheaper to run on diesel... what do you think they use?

 

The diesel engine was retro fitted to provide hotel power while the ship is in port. Prior to the refit while the ship was in port all hotel power was provided by one of the two gas turbines. The gas turbines are only "efficient" when they are fully or near fully loaded. While providing only hotel power, GTs are only lightly loaded and still consume a large amount of fuel.

 

Vessels that run a combination of gas turbines and diesel are what Princess uses on the Island and Coral Princess. Electrical generation is provided by two diesels and one gas turbine. All propulsion power for the Infinity comes from the gas turbines.

[dforeigner]

Most ship thrusters can only propel the ship sideways up to so many knots. If the wind is stronger and the capacity of the side thrusters, then the ship will need assistance from a tugboat.

 

Example, if the thrusters can only go up to 25 knots per hour and the winds are sustained at 35 miles per hour, the wind is going to win. :eek:

[WEGL81]

Low power, or lack of judgement?

 

https://www.youtube.com/watch?v=ehxiSLzP7Lc

 

 

Wow, that is a dramatic video. BTW, I was on Infinity when she went thru the Panama Canal. You should have seen the scrapes on her side coming out of that. Of course it's not the same thing. In my case they painted over them while docked in Cartagena.

[Tangocherie]

The diesel engine was retro fitted to provide hotel power while the ship is in port. Prior to the refit while the ship was in port all hotel power was provided by one of the two gas turbines. The gas turbines are only "efficient" when they are fully or near fully loaded. While providing only hotel power, GTs are only lightly loaded and still consume a large amount of fuel.

 

Vessels that run a combination of gas turbines and diesel are what Princess uses on the Island and Coral Princess. Electrical generation is provided by two diesels and one gas turbine. All propulsion power for the Infinity comes from the gas turbines.

 

BillB48, you are correct. However, If our other friend wishes to continue thinking the earth is flat, Kudos to him.:cool:

[RDC1]

I would not say under powered, as much as the amount of surface area on a modern cruise ship that is exposed to a cross wind. Recently I was on a Princess ship going around South America. In Ushuaia we had to stay longer due to a strong crosswind. The Captain was very nice and explained the issue in detail. He indicated that the thrusters can only be totally relied on in wind speeds of 25 miles and hour and lower. That at wind speeds above that the ship can run into problems. In those case they will request tug assistance if available or potentially skip a port.

 

Take a ship like the infinity which is 965 feet long. Even using the relatively rectangular flat area from Deck 2 to Deck 10 and reducing the length in the calculation to only from the bridge back you would get 900x80=72,000 square feet of surface area. A 25 mile per hour wind would generate 1.6 pounds of force per square foot of surface area. A 45 mile an hour wind would generate 5.2 pounds to square foot.

 

The formula is Pressure=.00256 X V^2

 

Now you calculate total force by F = Area X Pressure X drag coefficient

For a flat surface the drag coefficient is 2.0

 

 

So with a 25 mile per hour cross wind the total force on the ship would be 230,400 pounds of force that the thrusters would have to over come. At a stronger wind of 45 the force would be 748,800 pounds of force.

 

F = 72000 X 1.6 X 2.0 = 230,400

F = 72000 X 5.2 X 2.0 = 748,800

 

While cruise not a problem main engines and rudders/pods can handle it. When not moving forward and easing in port or trying to move away from a dock, different story.

[Tom-n-Cheryl]

I would not say under powered, as much as the amount of surface area on a modern cruise ship that is exposed to a cross wind. Recently I was on a Princess ship going around South America. In Ushuaia we had to stay longer due to a strong crosswind. The Captain was very nice and explained the issue in detail. He indicated that the thrusters can only be totally relied on in wind speeds of 25 miles and hour and lower. That at wind speeds above that the ship can run into problems. In those case they will request tug assistance if available or potentially skip a port.

 

Take a ship like the infinity which is 965 feet long. Even using the relatively rectangular flat area from Deck 2 to Deck 10 and reducing the length in the calculation to only from the bridge back you would get 900x80=72,000 square feet of surface area. A 25 mile per hour wind would generate 1.6 pounds of force per square foot of surface area. A 45 mile an hour wind would generate 5.2 pounds to square foot.

 

The formula is Pressure=.00256 X V^2

 

Now you calculate total force by F = Area X Pressure X drag coefficient

For a flat surface the drag coefficient is 2.0

 

 

So with a 25 mile per hour cross wind the total force on the ship would be 230,400 pounds of force that the thrusters would have to over come. At a stronger wind of 45 the force would be 748,800 pounds of force.

 

F = 72000 X 1.6 X 2.0 = 230,400

F = 72000 X 5.2 X 2.0 = 748,800

 

While cruise not a problem main engines and rudders/pods can handle it. When not moving forward and easing in port or trying to move away from a dock, different story.

 

Good to see that some people can still utilize math !!!

 

Tom

[Tangocherie]

Point well taken!