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Why no gas turbine-powered Carnival ships?


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I was wondering, is there any reason why Carnival does not operate any gas turbine-powered ships? They are more environmentally friendly than the more common diesel-electric propulsion. RCCL's Radiance Class (basically their equivalent to Carnvial's Spirit Class) are gas turbine-powered.

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I can't answer that with any level of certainty but I'd expect that one reason is that the diesel motors do far more than drive the ship, in fact, they don't... They produce electricity that drives motors that drive the propulsion system.

Cruise ships consume ENORMOUS amount of electricity as they provide us with amazing venues for our entertainment, ice for our DODs and comfortably cool cabins.

I know that the Navy has used GE LM2500s in destroyers and some fast attack ships. In those applications the LM2500s drive the propellers through a reduction gear without the benefit of an intervening electric motor.

By the way, that LM2500 is a variant of the high bypass fan used on the 747 and a variety of other aircraft...

:)

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Wow... this really is an interesting issue. The pros and cons are pretty complex and both solutions have large pluses and minuses.

Initial cost of the traditional diesel solution is apparently quite a bit lower than the gas turbine solution. Diesel engines are VASTLY heavier than their gas turbine counterparts but that's a two edged sword. Ships need ballast to stay upright and those huge 12 cylinder engines provide an amazing amount of ballast. This is an important consideration as ships get larger and, most importantly, taller.

Power up is quite a bit slower for the gas turbine v. the diesel... 30 minutes for the gas turbine and 5 minutes for the diesel. I'd expect that some additional planning could overcome this issue but one never knows...

You're certainly right about the eco-friendliness of the gas turbine engine but a great deal of that advantage is soon to be lost with the advent of diesel engines utilizing ultra low sulfur fuels...

Great topic! I've learned a lot!!

Thanks!!

:)

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I know US destroyers also have a turbine/generator to generate the electricity on the ship as well. So maybe the answer is more that a more highly specialized maintenance crew would be required to service and operate gas turbines.

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I know US destroyers also have a turbine/generator to generate the electricity on the ship as well. So maybe the answer is more that a more highly specialized maintenance crew would be required to service and operate gas turbines.

 

 

Those certainly are issues in addition to being able to provide the space and components to be able to swap out a gas turbine engine underway...

I've been reading an interesting comparison here:

http://www.mandiesel.com/files/news/filesof931/0200Gas%20turbines.pdf

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Those certainly are issues in addition to being able to provide the space and components to be able to swap out a gas turbine engine underway...

 

I've been reading an interesting comparison here:

 

http://www.mandiesel.com/files/news/filesof931/0200Gas%20turbines.pdf

 

For those who are looking foir the executive summary: Fuel cost for an ocean going gas turbine plant is almost twice that of diesel plant (using year 2000 oil prices). I imagine current propulsion system decisions, made at the executive level, are pretty easy to make given the current (and unpredictable) price of fuel.

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Also, it is my understanding that the ships don't run on "diesel" ( like the kind we put in our cars)....but a bunker oil .... which I would imagine is cheaper than the more refined "standard car diesel".

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I received an interesting email some weeks ago

featuring a large engine designed for ships.

 

Most people have no idea just how large and heavy these things are

but these few photos may serve to give an idea.

 

Engines this size or type may not even apply to cruise ships...I don't know.. :confused:

.....................................

 

This is what the crankshaft looks like!

Wartsila-SulzerRTA96-CCrankshaft.jpg

Notice the little ladder steps down each 'throw'-space..

 

 

Wartsila-SulzerRTA96-Cengine.jpg

Cylinder lineup!

 

 

 

Wartsila-SulzerRTA96-Cengine2.jpg

 

 

Maximum power: 108,920 hp at 102 rpm

Maximum torque: 5,608,312 lb/ft at 102rpm

 

 

 

Wartsila-SulzerRTA96-Cturbocharged.gif

Your finished product, Sir -please sign here..

 

 

______________________________________

This is the blurb wot came with the email:

 

The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine

is the most powerful and most efficient prime-mover in the world today.

The Aioi Works of Japan 's Diesel United, Ltd built the first engines

and is where some of these pictures were taken.

 

It is available in 6- through 14-cylinder versions, all are inline engines.

These engines were designed primarily for very large container ships.

Ship owners like a single engine/single propeller design

and the new generation of larger container ships needed a bigger engine to propel them.

 

The cylinder bore is just under 38" and the stroke is just over 98".

Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower.

Total displacement comes out to 1,556,002 cubic inches (25,480 liters) for the fourteen cylinder version.

 

Some facts on the 14 cylinder version:

 

Total engine weight:

 

2300 tons (The crankshaft alone weighs 300 tons.)

 

Length: 89 feet

 

Height: 44 feet

 

Maximum power: 108,920 hp at 102 rpm

 

Maximum torque: 5,608,312 lb/ft at 102rpm

 

Fuel consumption at maximum power is 0.278 lbs per hp per hour (Brake Specific Fuel Consumption).

Fuel consumption at maximum economy is 0.260 lbs/hp/hour.

At maximum economy the engine exceeds 50% thermal efficiency.

That is, more than 50% of the energy in the fuel in converted to motion.

 

For comparison, most automotive and small aircraft engines have BSFC figures

in the 0.40-0.60 lbs/hp/hr range and 25-30% thermal efficiency range.

 

Even at its most efficient power setting

the big 14 consumes 1,660 gallons of heavy fuel oil per hour.

 

.

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How's this for ballast Mach?? ;)

 

 

AWESOME ballast but not on a ship!!

A Conquest class has six Wartisla 12 W 46C 12 cylinder diesel engines that turn out 12,600 kW each. Talking about horse power makes little sense as they only drive generators, not propellers...

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Those photos are of a long-stroke, ultra-slow rpm direct drive diesel as would be used in a VLCC (Very Large Crude Carrier). The much smaller ones I have seen in some of the Canadian flagged Great Lakes carriers have strokes of over 7 feet.

 

The Wartsilas used in cruise ships are more like a railroad locomotive prime mover. This is a very efficient type of engine.

 

The gas turbine is a fuel sucking device unless it is run wide open 24/7. This thing uses almost the same amount of fuel (and it usually is bunker C, the same junk most marine diesels burn) if it is idling or running at 105% of power.

 

If the gas turbine was ideal for shipboard service, the VLCC fleet would be adopting it as these ships grind along for weeks at 10-12 knots and are rarely in port for more than 24 hours. This fleet is almost exclusively diesel powered except for the 30 and 40 year old relics that keep sailing for marginal operators.

 

Doc

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Also, it is my understanding that the ships don't run on "diesel" ( like the kind we put in our cars)....but a bunker oil .... which I would imagine is cheaper than the more refined "standard car diesel".

 

Yes that's correct. Bunker number6 heavy fuel oil looks almost like tar at room temperature and its still tied to the price of oil. Also the fuel refining requirements of a gas turbines are slightly higher than that of a medium speed diesel.

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The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine

is the most powerful and most efficient prime-mover in the world today.

The Aioi Works of Japan 's Diesel United, Ltd built the first engines

and is where some of these pictures were taken.

 

The cylinder bore is just under 38" and the stroke is just over 98".

Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower.

[

 

 

Even at its most efficient power setting

the big 14 consumes 1,660 gallons of heavy fuel oil per hour.

 

.

 

Helpped change the rings and a liner on one of these suckers my first week as a midshipman on the m/v Seawolf - way back in '87.

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:eek:MG -the things you learn on the CC Message boards!!

 

So...why then did RCCL opt to 'try-out' (?) the Gas Turbine thing

on the four Radiance Class vessels...never to repeat it again?

Was it a design experiment?

 

Was it a good idea at the time, or what?

Fuel was cheap back then?

What?

 

 

.

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As an ex-Coastie, I've worked on ships with both Diesel/Electric and Gas Turbines. Turbines tend to be not very economical at higher ship speeds. One class of ship I worked on had CODOG plants, two diesels for low speed (basically under about 17 knots) and gas turbines for high speed with the associated gearing to change between the two sources. The ship class I spent more time on was Diesel Electric. The advantage there was that if you are manuevering a lot (e.g. going ahead/astern ) repeatedly, diesel/electric drive is more responsive. Rather than waiting for your gearbox to slow down and stop then reverse, on an electric drive you are reversing the electric current flow which can be almost instantaneous. Watch Titanic and see how long it took to reverse those engines (verticle quadruple expansion). Those weren't turbines but still worked thru a gear train. Given that the Carnival ships generally do not use tugs much, at least as I have seen, the combination of the Azipods and thrusters give the bridge superb control that's almost instantaneous.

 

Interestingly enough, electric drives equipped some of the US battleships that were present at Pearl Harbor in 1941. They were of course powered by steam driven generators instead of diesels as there weren't diesels big enough to drive a battleship. World War II era submarines were also diesel electric. So the Diesel/Electric drives on the Carnival ships are in some ways a step back to the past. They are using high efficiency diesels and diesel's tend to run best at higher power ranges which a generator allows without varying the engine speed a lot.

 

The Navy uses gas turbines more for their acceleration I believe that economy. After all, the taxpayers pay the fuel bills for the Navy. Read somewhere the Navy is looking at going back to electric propulsion for some applications as it's a technically more efficient powerplant. Match the generator size to the most economical power setting on the generator and your all set. On the cruise ship's the trick I'm sure is balancing the Housekeeping loads (A/C, icemakers, cooking appliances and all the other creature comforts) and the propulsion loads. I would guess they drop generators off line late in the evening when everybody goes to bed then start them up again early in the morning to cook breakfast.

 

JMHO, your mileage may vary......

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:eek:MG -the things you learn on the CC Message boards!!

 

So...why then did RCCL opt to 'try-out' (?) the Gas Turbine thing

on the four Radiance Class vessels...never to repeat it again?

Was it a design experiment?

 

Was it a good idea at the time, or what?

Fuel was cheap back then?

What?

 

 

.

http://www.memagazine.org/backissues/membersonly/july98/features/luxury/luxury.html

 

"Green" was more en vouge. Was supposed to deliver less vibration too. Didn't seem to deliver on the vibration front, and RCCL learned the hard way that folks might like to say "go green" but they are seldom willing to pay for it. They're also not likely to buy into the "cutting edge" thing when the can't see it.

 

Fuel went way up, the diesel guys got better, and most of the turbines also got parred with AZI-PODS. Seems like real world results have proven both technogies to be better on the drawing board than in application. :rolleyes: While the gas turbine is certainly not new technology (its essentially a jet engine) most of the cogen stuff was more protoypical in nature.

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Yes that's correct. Bunker number6 heavy fuel oil looks almost like tar at room temperature and its still tied to the price of oil. Also the fuel refining requirements of a gas turbines are slightly higher than that of a medium speed diesel.

 

Yea.... I got one right!!! LOL

 

The things you learn from hanging around Captai Scala!!! :D

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The radiance class ships from RCCl such as the Jewel of the seas burns 35 gallons of fuel per MINUTE (yes minute)and is more exspensive fuel then the low grade stuff used by Carnival.I would say Carnival is smart for staying with the diesels from a business point.Maybe thats why Carnival is much cheaper to cruise then RCCL.I have been on both lines so i can compare.

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I was wondering, is there any reason why Carnival does not operate any gas turbine-powered ships? They are more environmentally friendly than the more common diesel-electric propulsion. RCCL's Radiance Class (basically their equivalent to Carnvial's Spirit Class) are gas turbine-powered.

Just a thought but, after the Radiance Class I don't think they ever used it on another ship......;)

Hmmmmmm.......

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AWESOME ballast but not on a ship!!

 

A Conquest class has six Wartisla 12 W 46C 12 cylinder diesel engines that turn out 12,600 kW each. Talking about horse power makes little sense as they only drive generators, not propellers...

 

That equates to about 16,900HP each (1kW = 1.341 HP.)...Probably about the size of the starter motor for that behemoth of an engine.

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