Cruise ship transformer fires - why no 'Back-up'?

I’ve been following the woes of Tui/Marella ship ‘Discovery’. Purchased by Thomson in 2017 from RCI, who ran her from new in 1995 as ‘Splendour of the Seas’. 70,000 GRT, 1800 passengers, 700 crew. Power 5 x Wartsila Vasa V12s, running 2 fixed props.
According to Cruisemapper, one month ago, Discovery experienced localised burning within the transformer housing. A similar incident happened on Nov 28th 2018 when another transformer “exploded” https://www.cruisemapper.com/accidents/Marella-Discovery-712
Discovery continues to limp on at reduced speed, requiring changes to itinerary, missed ports and extra days at sea. Ok these older ships, can afford to give discount fares, so passengers should complain about the odd breakdown. Apologies for my lack of techie knowledge but does anyone know how many transformers a ship like this would use and if it’s feasible to install back-up transformers when ship is new? TIA

A typical layout would be two transformers per propulsion motor and a whole bunch of smaller distribution etc. transformers.

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Thanks Tupsis, unfortunately there’s no information as to whether it’s one of the main transformers or one of the distributors that’s kaput. The German owned TUI and the British run Marella, are remaining schtum, as to detail (lol).

It seems that these units are quite large and it may not be practical to install new as back-up. For companies like RCI, there’s no financial incentive to do so, if the intention is to sell the ship at say, 15 to 20 years old. I guess the onus is on Marella to find a solution, if they want to keep their customers sweet.

My interest is due to the fact we sailed om her for 3 weeks in March from Laem Chabang to Colombo and everything worked smoothly. Loved every minute of it.

They obviously had a backup. They just had to sail at a reduced speed, same as if one of the 5 engines went down there are still 4 more running. These transformers take some time to remove and replace and will require specialist labor if you want it done right. Instead of having a backup you get the transformers tested periodically so that you know when it’s time to replace or repair. That way you can schedule it and not lose money and piss of passengers.

Ah, thanks twackineer, I guess they wouldn’t get licensed if there was no adequate backup against propulsion failure.

This is probably true. A propulsion transformer for a 21.5-megawatt propulsion motor such as that of Marella Discovery would be the size of a 20 ft container and weigh around 20 tons.

I think the most feasible option would be to have no equipment-level redundancy for 100 % propulsion power, but have the system split and separated in such way that even a “flashy” transformer failure would not reduce the available propulsion power on the shaft by more than 50 %. Now it seems that a whole propulsion line is lost due to a single equipment failure.

Forgive my ignorance, could this mean she’s doing 16 kts on one prop?
Incidentally, here’s an amateur vid of it’s sister ship, which uses the same five Vasa 46Bs. Does it show the propulsion transformers and generators you mention? TIA

That was pure speculation from my side based on the remark “The speed was limited to ~9 knots (17 kph / 10 mph) instead of the max speed of 24 kn (44 kph / 28 mph)”. I don’t know what the ship is capable of on one shaft only.

Looks like they just visited the main engine room and not the switchboard room where propulsion transformers are usually located.

Since AIS is showing her at 16 knots recently, and if her configuration matches the Viking Star above in some manner, isn’t it possible that one shaft is operating at up to half power (12 pulse operation, vice normal 24)?

Actually now I see you basically suggested that above.

I’ve been sick since Friday. Maybe that’s why that music made me want to stop living.

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Strangely, the naval base with the highest suicide rate is Portsmouth - https://www.youtube.com/watch?v=hpJ6anurfuw

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:rofl: :rofl:

I don’t care for the half second images … the moozak didn’t help either!!
There is maintenance to be done on transformers too … and they don’t often get much attention. It’s amazing how much krap gets sucked into the convection air cooling system on hot stuff. (and it burns)!
I doubt the ship gets much over ten knots on one shaft.

On the twin screw ships that I sailed on we reckoned to run at about 2/3 of full speed on one engine. If we could disengage the shaft and let it spin, or feather the prop, we might make a little more speed

No phone calls to the control room from hotel about some toilet not working because there’s bed sheet half way down? Not realistic…

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I was thinking there must be rule of thumb that would get in the ballpark.

The Hamilton class cutters would do 19 kts on one shaft and about 30 kts on two or roughly 2/3.

That would be with two gas turbines powering the single shaft, right? Not very comparable to merchant configurations.

No, same configuration, one Pratt & Whitney gas turbine engine one-line on one shaft and the other engine shut down with the shaft freewheeling. Was on board when it happened, 19 kts.