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How does a ship with four separate generators lose ALL power like Solstice in Seattle?

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12 minutes ago, Gram0707 said:

How does a ship with four separate generators lose ALL power like Solstice in Seattle?

 

Maybe the problem was  after the generators and before the power distribution.

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I don’t know, but I imagine that when something blows a lot of things trip to prevent damage spreading, so everything may shut down. It then takes some time to find the source of the problem and then work out how to safely restore systems without causing further damage. 

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All generators are driven by engines and when one or more of the engines has problems the other engines have to compensate. It appears in the case of the Solstice they experienced engine problems, cut back to emergency lighting, and headed for port. I would think they found the problem and fixed it, then turned back and a pilot boat brought the inspector aboard to certify the repair so they could continue their voyage.

 

If one of four tires on your car blows out how far can you still drive it? 🤔

 

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4 hours ago, Gram0707 said:

How does a ship with four separate generators lose ALL power like Solstice in Seattle?

Very often, not all generators are on line at one time, so for instance, leaving port, there will only be two generators on line due to low demand from propulsion.  Generators will be added when load increases, and shut down when load decreases, so there will only be sufficient generators online to meet the demand, yet if one of those generators fails, the demand may well overload the remaining generators.  For instance, if there are three generators on line, operating at 70% of capacity, and one engine fails, the other two generators will have to instantaneously supply 105% of their capacity (70% original load plus half of the 70% (35%) of the load from the failed generator.  At 105%, the generators will trip on safety protection to prevent damage to those engines, leading to a total power outage.

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We had this same exact problem ( from guest perspective) happen on the Equinox last fall with Capt Kate.

Stopped dead in the middle of the Carribean, no power or anything but emergency lighting no forward motion. DH was still in our cabin and he said fire doors were closed and he walked up to Oceanview where I watching from a window seat. About 45 minutes later thngs started to come back online and we continued on. During a meet the officers the question was asked "what happened" and Capt. Kate started to respnd but chief engineer interrupted and  said they just wanted a romantic breakfast for everyone.  They would not comment any more. We never did find out but the cruise continued on with no issues.

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57 minutes ago, chengkp75 said:

Very often, not all generators are on line at one time, so for instance, leaving port, there will only be two generators on line due to low demand from propulsion.  Generators will be added when load increases, and shut down when load decreases, so there will only be sufficient generators online to meet the demand, yet if one of those generators fails, the demand may well overload the remaining generators.  For instance, if there are three generators on line, operating at 70% of capacity, and one engine fails, the other two generators will have to instantaneously supply 105% of their capacity (70% original load plus half of the 70% (35%) of the load from the failed generator.  At 105%, the generators will trip on safety protection to prevent damage to those engines, leading to a total power outage.

 

Thank you very much as usual for your great explanation.  I might be able to add a practical example which comes from the Smithsonian Channels, "Mighty Cruise Ships"  Solstice.   This TV show which actually was on the other day depicts the Solstice several years ago on her first voyage to Australia..  During the show they kept cutting into engineering as they were extremely concerned about the heat down under and how much they had to push the ships AC.  I think they finally got to putting all the generators on but they were able to get through the heat.  Good show if its available for streaming or again on the Channel. 

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7 hours ago, dkjretired said:

 

Thank you very much as usual for your great explanation.  I might be able to add a practical example which comes from the Smithsonian Channels, "Mighty Cruise Ships"  Solstice.   This TV show which actually was on the other day depicts the Solstice several years ago on her first voyage to Australia..  During the show they kept cutting into engineering as they were extremely concerned about the heat down under and how much they had to push the ships AC.  I think they finally got to putting all the generators on but they were able to get through the heat.  Good show if its available for streaming or again on the Channel. 

Again, a lot of the explanations given on these kinds of shows skirts around the "real truth" of the matter.  It is not so much the heat of the air that causes problems for ship's AC systems, as the water temperature.  Both the diesel generators and the AC chillers are cooled by fresh water, that is designed to be kept at 30*C  (86*F).  This fresh water is cooled by the sea water, and when in tropical locations where the sea water temperature is around 30-32*C, you have problems cooling things.  Most ships, even with all the AC chillers online, would not require more than 2 engines if in port, and propulsion still takes up the majority of the load.

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9 hours ago, chengkp75 said:

Very often, not all generators are on line at one time, so for instance, leaving port, there will only be two generators on line due to low demand from propulsion.  Generators will be added when load increases, and shut down when load decreases, so there will only be sufficient generators online to meet the demand, yet if one of those generators fails, the demand may well overload the remaining generators.  For instance, if there are three generators on line, operating at 70% of capacity, and one engine fails, the other two generators will have to instantaneously supply 105% of their capacity (70% original load plus half of the 70% (35%) of the load from the failed generator.  At 105%, the generators will trip on safety protection to prevent damage to those engines, leading to a total power outage.

Hoped you would post to this thread.

So is this this most likely  explanation?

Still don,t know what caused the generator to fail if this is the case...

 

They  must have to file reports  but seems  they are not  made public!

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28 minutes ago, hcat said:

Hoped you would post to this thread.

So is this this most likely  explanation?

Still don,t know what caused the generator to fail if this is the case...

 

They  must have to file reports  but seems  they are not  made public!

Yes, there can be any number of reasons for multiple generators to fail simultaneously, including rare happenstances like the Viking Sky failure due to severe rolling and pitching combined with slightly low oil levels causing the generators to trip off line on low oil pressure.  But, yes, losing one generator, even if another is available in standby (it takes a minute or two for that standby generator to start up, reach speed, and synchronize to the power bus), can cause a cascade failure of the remaining generators due to overloading (just like one power plant failing on land can cause widespread power outages as other plants cannot take the surge in demand and trip off as well.

 

Typically, there is no "report" to file, the failure or reason for one generator to come off line will be simply an entry into its maintenance history with the cause and repairs noted.  If the blackout happens in restricted waters, as I understand this one did, then a national agency, in this case the USCG needs to be notified that the ship is now a hazard to navigation, and they will inspect the ship to determine if it is safe to proceed on its voyage.  No, they won't be made public, though some incidents are uploaded to the USCG Port State Control portal, but these are never timely.

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I asked my DH about the possibilities.. He lost me quickly . He gave me a long explanation that involved turbines etc..  He says he would need to know how they were hooked up ..lol!!  he is a marine electrician was  in charge of the Canadian naval ships. A much smaller scale but at least he has a base knowledge.. except how to explain to his wife

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4 hours ago, chengkp75 said:

Again, a lot of the explanations given on these kinds of shows skirts around the "real truth" of the matter.  It is not so much the heat of the air that causes problems for ship's AC systems, as the water temperature.  Both the diesel generators and the AC chillers are cooled by fresh water, that is designed to be kept at 30*C  (86*F).  This fresh water is cooled by the sea water, and when in tropical locations where the sea water temperature is around 30-32*C, you have problems cooling things.  Most ships, even with all the AC chillers online, would not require more than 2 engines if in port, and propulsion still takes up the majority of the load.

 

I haven't seen the show in awhile but what you are saying sounds familiar that they did mention about the water temps.  I don't know if you've seen the show  but it was more focused on the actual trip since it was the ships first trip to Australia.   All the Smithsonian's Mighty Cruise Ship shows do actually go into the engineering area's of the ship as well as a travelogue.   I am looking and hope they do something on the Edge.   Thanks again for the info..

Edited by dkjretired

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3 hours ago, gold1953 said:

I asked my DH about the possibilities.. He lost me quickly . He gave me a long explanation that involved turbines etc..  He says he would need to know how they were hooked up ..lol!!  he is a marine electrician was  in charge of the Canadian naval ships. A much smaller scale but at least he has a base knowledge.. except how to explain to his wife

 

I can identify with this!  My father is a heart surgeon.  If I asked him how someone was doing after surgery, he would launch into a long complicated explanation.  At the end I would say "Are they doing OK or at death's door; I couldn't tell."

 

We joke that on long drives my DH can keep me from falling asleep by trying to explain airspeed versus ground speed....

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On 7/22/2019 at 6:51 AM, chengkp75 said:

Yes, there can be any number of reasons for multiple generators to fail simultaneously, including rare happenstances like the Viking Sky failure due to severe rolling and pitching combined with slightly low oil levels causing the generators to trip off line on low oil pressure.  But, yes, losing one generator, even if another is available in standby (it takes a minute or two for that standby generator to start up, reach speed, and synchronize to the power bus), can cause a cascade failure of the remaining generators due to overloading (just like one power plant failing on land can cause widespread power outages as other plants cannot take the surge in demand and trip off as well.

 

Typically, there is no "report" to file, the failure or reason for one generator to come off line will be simply an entry into its maintenance history with the cause and repairs noted.  If the blackout happens in restricted waters, as I understand this one did, then a national agency, in this case the USCG needs to be notified that the ship is now a hazard to navigation, and they will inspect the ship to determine if it is safe to proceed on its voyage.  No, they won't be made public, though some incidents are uploaded to the USCG Port State Control portal, but these are never timely.

 

chengkp75, Don't you think they have a load shedding procedure on board so as not to put the generators over capacity?

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23 hours ago, helen haywood said:

We joke that on long drives my DH can keep me from falling asleep by trying to explain airspeed versus ground speed....

 

On your next long drive, ask DH to explain the differance between true, indicated, equivalent, and calibrated airspeed!

✈️ 

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23 hours ago, helen haywood said:

We joke that on long drives my DH can keep me from falling asleep by trying to explain airspeed versus ground speed....

 

7 minutes ago, Oviedo32765 said:

On your next long drive, ask DH to explain the differance between true, indicated, equivalent, and calibrated airspeed!

Ha! I tried this and my wife gave me ‘that thousand-mile stare’....and followed with ‘whatever speed you are using driving, don’t get a ticket and if you do, Do Not tell the police you were driving ‘indicated’, not ‘true’. Which meant, she really understood but won’t own up to it!

 

Two of our daughters a lawyers and will start going through the intricacies of the law.......so I fully understand the ‘eye glaze over’.

 

Den

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9 hours ago, TeeRick said:

 

chengkp75, Don't you think they have a load shedding procedure on board so as not to put the generators over capacity?

There is some load shedding, but only for major loads, like propulsion, thrusters, and AC.  If at sea, things like the thrusters are not running, so tripping them does nothing.    Typically load shedding is set for around 95-98% capacity, but if there is an instantaneous large overload (say two engines are on line at 80% and one trips, that puts an instantaneous 160% load on the remaining generator, too fast for the load shedding to work.  Hotel load, with the exception of the large load AC chillers, is never considered a sheddable load.

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Beyond me,  but I appreciate the  patience shown to those not able to comprehend the details. 

 

 Is there any increased likelihood this would happen again on a ship that had such a shut down?  Or random?  

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6 hours ago, hcat said:

Beyond me,  but I appreciate the  patience shown to those not able to comprehend the details. 

 

 Is there any increased likelihood this would happen again on a ship that had such a shut down?  Or random?  

Merely random failure of possibly a very small component in a very large system.

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12 hours ago, chengkp75 said:

There is some load shedding, but only for major loads, like propulsion, thrusters, and AC.  If at sea, things like the thrusters are not running, so tripping them does nothing.    Typically load shedding is set for around 95-98% capacity, but if there is an instantaneous large overload (say two engines are on line at 80% and one trips, that puts an instantaneous 160% load on the remaining generator, too fast for the load shedding to work.  Hotel load, with the exception of the large load AC chillers, is never considered a sheddable load.

Thank you for answering my question.  Much appreciated.

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3 hours ago, chengkp75 said:

Merely random failure of possibly a very small component in a very large system.

Thank you for being the "go to guy" for  these and many other issues!

Edited by hcat

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On 7/21/2019 at 3:43 PM, Gram0707 said:

How does a ship with four separate generators lose ALL power like Solstice in Seattle?

I heard someone kicked the plug out. Just a rumor

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