The Very Recent Engine Problem on Coral Princess

[rkacruiser]

Coral Princess was delayed for a few hours for her first of the Season arrival at Juneau due to an engine issue.  It has been reported on the Princess Message Board that the guests were told that the problem was with the ship's gas turbine.  It was posted that guests and a crew member noticed a starboard list with the Starboard screw producing a more significant wake than did the Port screw.

 

The primary engines on Coral Princess are diesels, I think.  The gas turbine is an auxiliary engine and increases fuel costs for the ship when it is used.  Am I correct in my thinking?   

 

I am thinking that a sufficient number of the diesel engines were off-line so that the gas turbine had to be engaged.  If so, does that account for less power been provided for the Port screw as compared to the Starboard screw?  If so, why, then, the list to Starboard?

  

 

 

[chengkp75]

Coral and Island Princess have 2 diesel engines rated at 15.6Mw each, and 2 gas turbines rated at 25Mw each, so the gas turbines are not "auxiliary", but produce 60% of the ship's rated power.  The power plant is what is called "CODLAG" or "combined diesel electric gas turbine" propulsion.  Here the diesels generate electricity, which is used for hotel load and thrusters, and also to power electric propulsion motors on each propeller shaft.  The big difference with CODLAG over conventional diesel-electric cruise ship propulsion is that there is a gas turbine directly geared to the propeller shaft.  So, unlike the Cunard ships, these gas turbines do not generate electrical power, but provide mechanical power directly to the propeller shaft.  So, without the port gas turbine, the port propeller can only run at the capacity of the electric motor on that shaft, probably no more than 10-15Mw, instead of the maximum power of the shaft of about 30Mw.  Virtually any time these ships are at sea, unless creeping along under 12 knots, they will be running the gas turbines for propulsion.

 

Not sure if the starboard list was connected to the reduced port side propulsion, but the steering would be heavily taxed to counteract the mismatch in power between the two props.

[MicCanberra]

Hope they can get any issues sorted before a cruise is badly affected or safety becomes a risk..

[chengkp75]

1 hour ago, MicCanberra said:

Hope they can get any issues sorted before a cruise is badly affected or safety becomes a risk..

Safety is not really an issue.  Each of two propellers (redundancy there) has two means of power, electric motor and gas turbine, so there is a secondary redundancy there as well.

[MicCanberra]

Yep and yet ***** can happen, like on the Viking Sky.

[chengkp75]

Which just goes to show that bad things can happen whether the ship has a propulsion problem already or not.

[Heidi13]

Chief - From memory the Island/Coral's propulsion is a little different from the more traditional CODAG arrangement. From memory, I believe she has 2 - Wartsila V16 medium speed diesels and a single LM 2500 GT, which is located on the Sun Deck at the base of the funnel.

 

For normal cruising they run on the 2 diesels and only put the GT online for high speed runs.

 

The Diamond & Sapphire were similar, but have 4 diesels + an LM2500 GT also at the base of the funnel.

 

Memory is certainly a bit hazy, as it has been over 5 years since we have been on any of the ships. Will verify with our son, who sailed on all 4 ships.

 

 

[chengkp75]

1 hour ago, Heidi13 said:

Chief - From memory the Island/Coral's propulsion is a little different from the more traditional CODAG arrangement. From memory, I believe she has 2 - Wartsila V16 medium speed diesels and a single LM 2500 GT, which is located on the Sun Deck at the base of the funnel.

 

For normal cruising they run on the 2 diesels and only put the GT online for high speed runs.

 

The Diamond & Sapphire were similar, but have 4 diesels + an LM2500 GT also at the base of the funnel.

 

Memory is certainly a bit hazy, as it has been over 5 years since we have been on any of the ships. Will verify with our son, who sailed on all 4 ships.

 

 

Could be, I'm working off the definition of CODLAG.  CODAG would have the diesels directly geared to the propellers as well.  Anyway, I checked, and you are correct, that she has only one gas turbine.  However, given that the diesels total only 30Mw, if you take out 8-10Mw for hotel load, you aren't getting a lot of propulsion power without the gas turbine.  I'd be surprised if she could do more than 12-14 knots without the turbine.

[DirtyDawg]

1 hour ago, Heidi13 said:

Chief - From memory the Island/Coral's propulsion is a little different from the more traditional CODAG arrangement. From memory, I believe she has 2 - Wartsila V16 medium speed diesels and a single LM 2500 GT, which is located on the Sun Deck at the base of the funnel.

 

For normal cruising they run on the 2 diesels and only put the GT online for high speed runs.

 

The Diamond & Sapphire were similar, but have 4 diesels + an LM2500 GT also at the base of the funnel.

 

Memory is certainly a bit hazy, as it has been over 5 years since we have been on any of the ships. Will verify with our son, who sailed on all 4 ships.

 

 

 

1 hour ago, chengkp75 said:

Could be, I'm working off the definition of CODLAG.  CODAG would have the diesels directly geared to the propellers as well.  Anyway, I checked, and you are correct, that she has only one gas turbine.  However, given that the diesels total only 30Mw, if you take out 8-10Mw for hotel load, you aren't getting a lot of propulsion power without the gas turbine.  I'd be surprised if she could do more than 12-14 knots without the turbine.

 

So, when the Captain presses down on the accelerator peddle, the boat is going to go, but he probably shouldn’t take it on the Autobahn. 

 

[ldubs]

1 hour ago, DirtyDawg said:

 

 

So, when the Captain presses down on the accelerator peddle, the boat is going to go, but he probably shouldn’t take it on the Autobahn. 

 

 

Only if he stays in the right lane.  😀

[Heidi13]

4 hours ago, chengkp75 said:

Could be, I'm working off the definition of CODLAG.  CODAG would have the diesels directly geared to the propellers as well.  Anyway, I checked, and you are correct, that she has only one gas turbine.  However, given that the diesels total only 30Mw, if you take out 8-10Mw for hotel load, you aren't getting a lot of propulsion power without the gas turbine.  I'd be surprised if she could do more than 12-14 knots without the turbine.

Our son has worked on all  4 GT ships up to S/2/O and responded they could make about 16 kts without the GT. We cruised on them extensively and I walked the upper deck daily. Very seldom heard the GT running.

[AL3XCruise]

On 5/12/2019 at 4:33 PM, chengkp75 said:

The big difference with CODLAG over conventional diesel-electric cruise ship propulsion is that there is a gas turbine directly geared to the propeller shaft.

 

What is the benefit to this arrangement?  My understanding was most modern large vessels, with the exception of those freighters running very large slow turning diesels, were generally using integrated electric propulsion.  Even the new Columbia class submarine is apparently using a turbo-electric drive.  Were suitable electric motors not available or relatively new when Coral entered service?

 

6 hours ago, Heidi13 said:

which is located on the Sun Deck at the base of the funnel.

 

I read an interview with Stephen Payne where he mentioned that one of the benefits of the integrated electric propulsion was that the QM2's gas turbines could be mounted on the upper decks; a shaft-driven arrangement would have required them to be placed lower in the ship where intake and exhaust issues would have been more complicated.  I'd be curious how Coral (or comparable ships) ran a shaft like that.

 

As always, thanks to both of you for your input!

[chengkp75]

6 hours ago, AL3XCruise said:

 

What is the benefit to this arrangement?  My understanding was most modern large vessels, with the exception of those freighters running very large slow turning diesels, were generally using integrated electric propulsion.  Even the new Columbia class submarine is apparently using a turbo-electric drive.  Were suitable electric motors not available or relatively new when Coral entered service?

 

 

I read an interview with Stephen Payne where he mentioned that one of the benefits of the integrated electric propulsion was that the QM2's gas turbines could be mounted on the upper decks; a shaft-driven arrangement would have required them to be placed lower in the ship where intake and exhaust issues would have been more complicated.  I'd be curious how Coral (or comparable ships) ran a shaft like that.

 

As always, thanks to both of you for your input!

I appear to be mistaken, and the Coral has a integrated electric system as Andy says.  The vast majority of "modern large vessels" are those freighters running low speed diesels directly connected to propellers.  Only ships with large hotel electrical loads and multiple propellers find a diesel electric or integrated electric plant to be efficient.  

 

Are you asking how an engine room mounted gas turbine would be shafted?  If so, the propeller shafts would be placed similar to all of the Princess ships, and with propulsion motors on the ends, just like all Princess ships.  However, between the shafts would be a gearbox and clutch arrangement and the gas turbine, much as shown here:

 

[Heidi13]

Only got a quick look at the GT space from the door and it was many years ago. I believe they had the LM 2500, an alternator and separate switchboard.

 

When bringing the GT online, I believe the GT switchboard can provide power to both shaft propulsion motors, but will defer to the Chief's greater knowledge of power distribution systems.

 

Affirmative the benefit of placing the GT on the upper decks is the ease of providing intake air, as the supply vents were extensive. It moved lots of air and the noise was considerable when walking the decks.

 

 

 

 

[chengkp75]

1 hour ago, Heidi13 said:

Only got a quick look at the GT space from the door and it was many years ago. I believe they had the LM 2500, an alternator and separate switchboard.

 

When bringing the GT online, I believe the GT switchboard can provide power to both shaft propulsion motors, but will defer to the Chief's greater knowledge of power distribution systems.

 

Affirmative the benefit of placing the GT on the upper decks is the ease of providing intake air, as the supply vents were extensive. It moved lots of air and the noise was considerable when walking the decks.

 

 

 

 

Yes, if there is only one GT, then it will be able to power both propulsion shafts via the electrical bus.  The other benefit of having the GT up high is the ability to change out the entire module more easily.  I know the LM2500's have come a long way, when GT's were first used by the US Navy (the old USS Callahan), they were changing GT modules out every couple of months until they got the blade metallurgy and coatings right for diesel fuel.

[Heidi13]

8 minutes ago, chengkp75 said:

Yes, if there is only one GT, then it will be able to power both propulsion shafts via the electrical bus.  The other benefit of having the GT up high is the ability to change out the entire module more easily.  I know the LM2500's have come a long way, when GT's were first used by the US Navy (the old USS Callahan), they were changing GT modules out every couple of months until they got the blade metallurgy and coatings right for diesel fuel.

Never sailed with a GT, even the big fast ferries we built on the West Coast were diesel (grossly underpowered). Only one I saw in the ER was on the Canadian Frigates, when we did the exchange visits. Got a tour of the ER and noted it was right in the middle of the space in its own little compartment.

 

That would have been a huge job to switch it out.