NTSB Dali Ship/Bridge Collapse Report: Surprising Findings
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- Опубліковано 13 тра 2024
- Jeff Ostroff walks you through the NTSB preliminary report on the Dali ship collision with the Francis Scott Key Bridge in 2024. This easy-to-follow analysis simplifies the report, making it easy for non-technical people to understand the official investigation so far and what they have discovered.
NTSB Accident Number: DCA24MM031
NTSB IMO Number: 9697428
NTSB Investigation ID: DCA24MM031
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There are also more updates on the engineering disaster salvage operation of the MV Dali ship striking the Francis Scott Key Bridge causing the bridge collapse in Baltimore, Md. on the Patapsco River. The video also shows how salvors installed the detonators for using precision-cut demolition explosives to break apart the bridge truss and force it to slide off the MV Dali in pieces.
The MV Dali collided with the Francis Scott Key Bridge in Baltimore, MD on March 26, 2024. You'll see progress so far in this Baltimore bridge collapse. - Навчання та стиль
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0:31 Did you just say "Truss me"?
I wanted to share with you when you where taking about placing a fridge in a tough spot. My Grandpa's house, when he made it his own. There was steps going to the basement and above the steps there used to be a closet in the kitchen area over the Basement steps. He chose to remove that closet and install his refrigerator there. The Refrigerator sat up, off of the floor a bit. I think he elevated the floor, or maybe it was already like that? He made a cut out on the back side of the closet at the bottom, so the Refrigerator could be worked on from the shallow basement steps ( Plus it allowed a place for heat to escape). ( Wish I had pictures, it was neat. Anyhow I felt like sharing that with you. Thanks for all that you do.
As someone who knows nothing at all of shipping or navigation, thanks for a clear & simple explanation of the report & sequence of events. It sounds like the crew scrambled to fix the problem very quickly & efficiently, it all just happened too fast to save those 6 men. Very sad.
Yeah, that seems to be the issue and yet the corrupt #FBI was brought in anyhow..... go figure, perhaps they the FBI are trying to find blame where there is none.
They should have closed and evacuated the bridge immediately the ship lost engine power and with even the remotest possibility of a collision.
@@BG-sl9lvImmediately?? If only life worked like that.. reminds me of an expression.. when seconds count, police are only minutes away..
As a maritime chief engineer I noticed a power management failure. They had the both MSB section connected instead of disconnect the separator and to have separate power supply for BT and the rest of ship's consumers including reefers coonection.
This report prove what I said before. No actions were taken following the several black-out they had while alongside. When you know you CAN HAVE power failure as the initial problem wasn't solved, to let the tug boat go before clearing the bridge was the biggest mistake captain took.
Human error is the main root cause of the incident.
@BG-sl9lv THEY DID evacuate the bridge as quickly as they could. Stop being an ashole
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My Dad was a master electrician for over 50 years. My step-son is an electrical engineer. Here's my safety tip of the day:
You do not ever close a tripped breaker until you find the cause of the short and clear it. Doing so can cause an electrical fire.
Good common sense!
There are worse things to happen than an electrical fire. At these voltages and currents, things can get explodey without warning
That's the part i can not understand. Why did they closed the LR1 + HR1 after they tripped?
The System is redundant, they can reroute with RL2 + HR2.
Closing a tripped breaker without clearing the cause, is also likely to cause upstream breakers to trip. (If there is sufficient other load on them.)
Should be kind of common sense, if the breakers on one side of the redundant system fail, you close those on the other part. not the ones that just tripped.
@@carbuying Not so much any more. Common - ain't.
I worked on jets. Any phase with a high resistance point, the other phase will overload and trip.
That was a brilliant explanation of the issues on board leading up to the collision. Even I understood the electrical diagram, thank you!
It seems like reversing the Dali was about as easy as reversing the Titanic in 1912.
Thank you for your clear and concise explanations. One thing that needs to not be forgotten in all of this, which it looks like is not going to be part of the official final report, is that the Port Authority and the contractor working on the bridge were negligent in not giving the workers a radio to communicate with the bridge police in case of an emergency. So, for want of a $500 walkie-talkie six men needlessly lost their lives. From the timeline, they clearly would have had enough time to get off the main span of the bridge back to one of the approach spans that did not collapse before the ship struck the bridge if the police had been able to radio a warning to them.
Even being able to be alerted via mobile phone would have saved them. I'll guarantee the contracting company had their numbers on file and nobody thought to try calling
@@miscbits6399 From what I have gathered, their employer was a relatively small company, and I doubt that anyone was in the office at 1 am to call them. The question is did the bridge authorities have any emergency contact information for them, and if not why not? Also, having worked in transportation (railroad), having a direct radio link to supervision can be critical in an emergency. There just wasn't any good reason for them not to have a radio of some kind. These days they are not that expensive or bulky.
This is a very good point that I hope doesn't get swept under the rug.
They may have had walkie-talkies but being on a break they might have left them in the vehicle or out of the vehicles. I’ve driven over the bridge and do not remember if there was a dead cell zone but driving 55 mph I doubt anyone would notice if there were. They may not have had enough time to notify them.
No radio needed- everyone has a cell phone these days, they could have simply called the foreman's cell
Jeff - About the breakers tripping - what you've neglected is that the generators are all 3 phase AC. For two or more generators to power one bus, their outputs must remain in exact phase lock. You notice that on the electrical panel there are three meters on each block - current or voltage of the 3 phases.
Keeping separate generators in sync is actually quite tricky. And if they drift out of phase, HUGE currents flow between the generators. From the sequence of breaker trips, it seems to me that after the emergency generator came on, every single breaker trip was probably due to loss of sync of one or more generators. Especially the final trip, when DGR3 and DGR4 tripped simultaneously - that would happen if one of those two generators lost sync with the other one. And that might have happened due to a transient sync loss with the running emergency generator.
In which case none of the trips were due to overloads or failures somewhere else in the system. Just very fast transient loss of sync of the generators. Which are going to be pretty hard to pin down and identify cause. Might even be purely operator error, since the proceedures for gaining and retaining phase lock are a bit subtle. I'm not sure what kind of automation for that would be used on a ship. For big power stations, if manually syncing up with the grid before connectiong a multi-megawatt generator, there's a meter called a synchroscope, that shows the phase difference between the generator and grid. A needle rotating 360 degrees continuously, with the rate or rotation showing any slight frequency difference. Get the needle stopped, means the frequencies are the same. Then jog the generator till the needle is stopped at 'zero degress difference' - then you can close the main connecting breakers.
On that ship the lock-in would likely be automated. And something went wrong with that system. At least twice. I wonder if that automation had any kind of open Net connection?
Yes, good points on the sync between the generators
The systems should take care of auto-syncing though.
I remember Chris Boden speaking of syncing a power station, well he said a small Hydro of around 250 KW from memory and he said bad things happen if you get it wrong.
Once two generators are interconnect, they automatically keep in sync with each other. Each has a speed governor and they both increase or decrease power as he frequency drops or rises. Some human intervention might be needed to balance the loads.
Hmmm yeah I was wondering about that, especially with the low and high voltage systems. My understanding is that on the HV system once the phases are locked that they cannot become unlocked since the power keeps the generator locked. I’m wondering how the system is supposed to behave if the HV and LV systems are out of sync since you have a tiny generator through a transformer which could easily explode the smaller generator if the HV system came online out of sync.
Wonderful explanation of the electrical system !!! This was very informative and interesting !!! Thank you for taking the time to explain all of this info to all of us !!! You are a wonderful teacher !!!
Thank you for keeping us updated on everything
I'm glad you appreciate the updates!
@@jeffostroffbarge hit Texas bridge causing partial collapse. Check the news
Jeff, thanks for guiding us through this report. I think you've done an excellent job of bringing the electrical elements down to earth for most of your subscribers, while giving us electrical nerds plenty of information to ponder
Thanks Rick glad to help
I'm really loving these updates Jeff..I might not comment on all your videos but rest assured, I'm watching with great interest,thanks Jeff
The apprentice pilot got one heck of a learning experience. I'm not sure if that would dissuade them from such a career, or serve as the new textbook example of "what's the worst that could happen?" and make that person especially careful in future situations like this.
They’re already well into a maritime career by the time they become an apprentice pilot. What else are they going to do?
@@randbarrett8706 heck most of the officers on the titanic went on to serve for many more decades.
Thanks for your great analysis Jeff, please keep us updated.
Thank you Jeff. I'm clueless when it comes to Structural or Mechanical Engineering, but you make me actually WANT to understand this stuff!
Thx for the quality review, we lay folks appreciate your time and effort.😊
Tugs usually want to release lines at any speeds 5 kts and faster for safety and ships want to leave port at the channel speed limits of the usually 10 kts. Escorting tugs would need to reconnect lines to safely get control of ship and at 10 kts just pushing will do little to alter course quickly. In this case even connected tugs and the ship only doing 4 kts it still would have been hard to prevent the collision, large ships like this are very hard to stop quickly.
The main propulsion engine is over 20 feet tall and takes a minute to start with a sequence of events that need to take place, it's not a push button electric start in a second method.
I think the Dali dropped anchor and anchor chain crossed over their 7kts velocity vector and turned the Dali into the allision with the Key Bridge. The dragging achor _cause_ the Dali turning south after losing power and control of the rudder/screw propulsion.
@@Carlos-im3hn crew member stated he did not apply the chain brake so the anchor might not have had any effect at all.
@@gerritvisser Correct. The anchor chain was just paying out, no effect.
They didn't have the anchors "ready to drop", one mistake. St-by crew wasn't at anchor station at that time, second mistake.
As you can notice from the report first order was TO PREPARE the anchor not TO DROP IT AT ONCE, meaning the anchor was in the deep sea state, secured and locked. HUGE MISTAKE during maneuver on such passage. Until you are in open waters, clear passage from any buoys, ship's anchors should be "ready to drop", hanging few meters above the water and st-by crew at anchor station.
@Carlos-im3hn ZERO evidence for anything you just said. Stop guessing randomly & keep quiet
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Thanks for the in-depth explanation of the failure. I'm really enjoying your videos about the Key bridge disaster.
Jeff, thank you very much for the very detailed analysis.
I'm amazed how big and how complex this machinery and electrical system are.
Jeff, thank you for a fantastically clear explanation of that report. What a great job! So much appreciated!!
Glad it was helpful!
Great stuff as always!
Thanks Jeff for another excellent report. I love listening to your voice and how you explain the technology in ways we can understand.
Thank you for this amazing and simplified explanation!
Thank you. Very easy to follow along.
Thanks for sharing the information and your analysis and commentary.
I understood this video completely. Thank you for being so clear.
Thanks for the overview and update Jeff. 😅.Greg. 😊.
Very informative. Your explanation was outstanding.
Thanks for your clear explanation of the NTSB Dali Report. Well down.
Great work as usual Jeff, we need you reporting on all engineering mishaps or failures.
Thank you for the clear explanation of the electrical system. Well done as always.
Very good explanation. Thank you for creating this report.
Very interesting and detailed explanation. Thank you
You have been my go too guy for this tragedy. Thanks for your well done explanation!
Excellent reporting Jeff!
Thanks for the explanations in this very interesting video. 🙂
Thanks Jeff, great break down.
Outstanding coverage Jeff!
Glad you enjoyed the coverage, I aim to please!
From the appearance of the unified control panel, the 4 center cabinets appear to be the four high voltage generators, and each has three meters at the top. The NTSA diagram you used did not specify whether the voltages were AC or DC, but again, from the cabinets I suspect that the four main generators are 3 phase AC. When HR1 and LR1 opened, the emergency generator started. Generators DG3 and DG4 started and the crew closed the HR2 and LR2 circuit breakers. At this point the emergency generator was still operating. If the operators did not remember that the emergency generator was operating providing the 440v power, and they did not phase match the main generators with the emergency generator, the conflict between the phases is probably why the DGR3 and DGR4 breakers blew. It is unclear why HR1 and LR1 blew, starting the whole process, but it was probably a completely different reason than what caused DGR3 and DGR4 to trip when power was being restored.
Makes sense. We still dont know the beggining of the story....
Thank you for your reply. L.
The high voltage and low voltage busses are AC because transformers only work on changing currents.
I too suspected poor matching of phase or frequency between the main and emergency Diesels.
An automatic system should control the paralleling of two AC busses during brief periods to switch from one to another.
If paralleled and one rotating machine has a sudden problem, relays will sense overcurrent or reverse power etc and initiate a trip.
You would think with all the automation in the electrical systems that phase matching would happen automatically as well.
So you think phase matching was a manual labor for a crew member? Not an automated process?
Love this detailed explanation.
Brilliant video. Thank you very much.
Glad you enjoyed it!
So, while the semantics differ, the powerless the prior day was equivalent to the guy working on the motor plugging the tailpipe with a potato - it differs in that it's case of operator error, not malicious tampering or bad design - but power loss the day prior was not a design flaw.
I was exactly thinking about the potato in the exhaust too XD. And yup, this has nothing to do (apparently) with what happened after.
Thank you for such a detailed explanation.
Your appreciation means a lot! I strive to provide value in every explanation.
Great explanation of the ships electrical system. Thanks Jeff
Very well done flipping between the text and the functional electrical drawing. Thank you. A sad issue not discussed by anyone is that near-bankrupt Sri Lanka dearly needs the supplies they have ordered and now they are unavailable due to damage, lack of a ship at the moment, and, I'd bet, lack of insurance.
Sri Lanka is in somewhat better shape now, inflation is back to normal, and reserves are improving, but these kind of problems never help.
@liam3284 SRI Lanka will survive just fine without one ship (especially one filled with perfumes & stolen cars). They’ve got 100s more ships making deliveries
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Love your engineering reports. Very clear for the lay person! You are number one for the Key bridge!!!😊
Thank you! 😃
Awesome report. This is what most of us been waiting for. Thanks' much for detail that a common guy can understand.
@Howard-ur2rj YOUR last sentence is not written using english grammar
@@electrictroy2010 lol. Sometimes proper " English grammar" becomes an option on my side of the tracks. ya know .... fixed. good catch . Are you a teacher ??
Sounds like frequency/phase automated synchronization system issue overloading the breakers while trying to transfer load between different generators/busses…
Jeff you did your self proud with this report. Thank you !
Thanks so much!
excellent review.
Very good explanation. I worked in a steel mill. We had a very similar redundancy for the electrical system at the water treatment plant. Every once in a while a breaker would trip for no reason at all. Many people looked at the system...over several months...found nothing wrong....looking for the needle in a haystack... Finally (Fortunately) somebody was standing there when the breaker tripped. The person noticed vibration from a nearby rail line. To make a long story short...there was a slightly loose control wire in one of the cabinets. The low voltage cabling (breaker control) for these breakers is somewhat of a nightmare. I am quite sure these container ships have a lot of vibration.....
I had a similar story in an iron sands extraction barge with phone service via radio link. it took us _years_ and a visit late on a Friday night to realise someone had wired critical equipment (the phone system) to non-essential power and service was being carried by lead-acid batteries which had been steadily degrading for 15 years due to the repeated deep discharge cycles that they weren't designed for
The fix was trivial, but finding a fault which simply doesn't exist during standard business hours was more or less impossible (the supply was labeled as essential power. It was only tracing back to the breaker panel which revealed the error)
Great work Jeff, thanks for your review and calming voice while analyzing details. Do we know why breakers intially tripped?
not yeah, they mentioned at 24:00 that they are still review to figure out why they tripped in the first place.
Great report Jeff , " screendoors on a submarine", None of this is anything to laugh about, but that comment had me in stitches Thank you so much for bringing us this report. Very understandable the way you've explained it. ~K~
great explaining
This is interesting watching this and then watching the video seeing it all in action
Very good report
Nice in depth summery
Thank you.
Sounds like a perfect storm of failures from both the ships systems and the ships crew...great breakdown Jeff!
_and_ the ship's location. If it had happened 10 minutes earlier or later it would have essentially been a minor incident
@miscbits6399 THIS loss of ship power has probably happened many times over the last 40 years. We were just lucky it happened away from the bridge.
This time… luck ran out.
Excellent video…..
Great explanation. Ironically as I’m watching this a Barge hit a rail line bridge in Galveston partially collapsing it!
You said you was going to make it simple to understand ...and you did. A mystery as to why 4 of those breakers tripped. Thanks for the update.
Thanks Jeff this 70 year old woman from Tennessee is learning a lot from you
People who work on giant road bridges like this one must constantly think about what could kill them, probably never that a transformer and a couple of circuit breakers going wonky...
I think the Dali dropped anchor and anchor chain crossed over their 7kts velocity vector and turned the Dali into the allision with the Key Bridge. The dragging achor _cause_ the Dali turning south after losing power and control of the rudder/screw propulsion.
thanks for your explanation. caroline
It was interesting that there was a crewman on the bow trying to release the brake on the port anchor that had to escape the falling roadway before he could reapply the brake. Imagine being that crewman and seeing the roadway headed toward you!
Or imagine being the lead construction worker on the bridge trying to outrun the collapse! That sounds like something out of an action movie where the lead character runs as fast as he can and makes it to safety just before whatever he was standing on collapses. I thought he just rode the collapsing bridge on down and was able to swim away from the wreckage....
@leeriffee4606 THE report says only the bridge inspector escaped. All the construction workers fell down with the bridge. One managed to escape from his submerged truck & swim ashore
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Excellent report Jeff. It all made perfect sense to me since I spent 35 years working on land based electrical substations. Your explanation was sure to help non electrical persons to more easily understand the protective processes.
Thanks for update.
Always welcome
Thanks for this summary of the NTSB investigation report. As there doesn't appear to be any other contributing factors or parties to this disaster, it's almost certain that the shipping company's insurer is going to be facing massive claims to pay for the bridge replacement, removal of the collapsed bridge, compensation for the victims, economic losses by other shippers that couldn't in or out of the port, etc. What a mess!
Or just declare bankruptcy & pay no one
.
FWIW, the DGRs would not trip for something on the LV BUS, because the TR related breakers would kick in well before a LV BUS short would bring down HV BUS. I can't wait to find out what caused the current surge to drop the generators offline.
Came here to say this. While I suppose it's possible that the LV BUS might have been able to bring down the HV BUS if the TR breakers had been damaged in some way, I feel like the report would have stated as much.
@@Cyberguy42 TR does not stand for a breaker but a transformer. and it may well be the culprit.
Anyways, when LR1+ HR1 tripped, they should have used LR2 + HR2. Maybe even open LVR and HVR, to be sure to isolate the fault. Not enough details.
Under normal operation that's true, but remember that while there was an unidentified high load (the cause of original failure that tripped breakers HR1 and LR1) on the LV buss, the crew manually closed breakers HR1 and LR1 and that exposed the high voltage buss to the original cause of failure. When a transformer under too high a load is suddenly re-energized, it has an inductive kick or bounce which will add even more trouble to the existing problem. There also wasn't a mention that the crew removed the emergency generator from the LV buss before closing the breakers for transformer 1. When on emergency power, according to that diagram, they shouldn't have closed breaker LR1 which shouldn't have been possible. You don't want two generators feeding the same buss/circuit unless they're synchronized like the main generator pairs.
Note that the bow thruster could have been powered directly by any of the four main generators to very slowly turn the ship away from the bridge.
@@DrJuan-ev8lu You might want to check again about the power of the bow thruster. I'm pretty sure it barely influences the ship at rest.
Jeff, thank you for your clear and easily understandable explanation! Great content as always although, I was slightly disappointed to not see any memes in this one! ❤🙃
I had one meme in there
Thank You for the expert information as to why the Dali struck the bridge.
Great explanation Jeff!
Your video was so interesting! Thank you so much! I wonder if you remember early on there was information about some refrigerated containers being added to the electrical system and there being some question as to whether they were contributing to the power constraints. The compressors cycling could cause intermittent overloads to an already strained power grid. Just saying. Do you have input about that? Thank you again.
I’m a retired breaker specialist and power distribution electrician, my guess is they are going to find that the coordination settings for the various trip devices on the breakers was not correct and/or the breakers were not properly maintained.
if it is like this, the fault is from manufacturing,
but as several breakers trip, chance of being all incorrectly set is low (only if all was changed)... usually high power breakers have electronic tripping, so no maintenance required..
@@user-ug9nnunless someone dorked up the control power circuit, esp the controller.
@@user-ug9nn It is not the manufacturers fault. The electrical engineer that designed the system is supposed to perform a coordination study and supplies the appropriate settings to the contractor that is installing the equipment. During commissioning of the systems all of this is supposed to be tested and verified. And everything needs maintenance even the breakers. I do this for a living, I'm an electrical engineer.
I suspect when the dust settles, it will be a wiring " gremilin"..a mouse or rat chewed insulation..or a bare wire occasional short..or..a faulty alarm sensor. It may be an actual alarm, on an obscure component.
@@eagle2019 it would not surprise me one bit if someone changed the settings the coordination study suggested. Happens all the time on shore. No reason it would not happen on ship.
Jeff, thanks for mentioning the last worker's body has been recovered. I had not seen that anywhere else.
Last Thursday, May 9, 2024.
I’m curious what do you think will happen to the Dali after this is all said and done, do you think it will be repaired and go back into service at some point?
Yes. Patched in NORFOLK then refitted, renamed and reflagged..
Ty 😊
thank you
Usually an actual overcurrent fault on either 6kv or 480v will leave plenty of physical evidence. All of the HV breakers that I’ve seen are opened and closed by solenoids (often from a battery bus) and the breakers themselves don’t directly measure the fault current/frequency error etc. That is done by separate sensors that trip the solenoids. Since each attempt to close breakers was at least temporarily successful it seems probable that there wasn’t a true overload, but some sort of control issue causing breakers to open erroneously.
2:58 recall on one older boat, the way to reverse the motor was to (physically) flip the cam shaft over.
Knowing the ship's limitations, and knowing the risks of problems, why not tug escorts under the bridge?
Ratchet Head
Complicates
Exhaust & Intake
Valves Functions?
A 2-cycle engine is able to be run in either direction.
@@royreynolds108 so can (some older) diesels - but would need an oil pump that works both ways (plunger style?) to keep lubrication supplied.
Thank you so much! Main stream media had only a sound bite & no real clue about what the repot was saying, so I KNEW you would break it all down. 🎉 Do all cargo ships have this same design? How might this disaster impact immediate changes & ship design in the future?
@fletch2681 EVERY ship has a different design, just as every model of car has a different engine & electrical design
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Thank you for this video. You did an excellent job explaining things to those of us who have no clue. It was very interesting. I enjoy your videos and enjoy listening to you.
Whoosh…….Jeff it went over my head. I did understand parts. Were those two busses the kind that have wheels that go round and round?
Some comments (I have years of experience with 16000 HP medium speed diesels). 1 the electrical set up on this ship is typical). 2 the engineering crew appears to have responded appropriately in this situation. 3 it would take at least 2 to 3 minutes to restart this engine (this isn’t like the diesel engine in your pickup or 18 wheeler folks) let alone getting the ship itself moving. When the breakers first tripped and shut down the lube pumps system the ship and the bridge (and the workers) were doomed
Why were the tie breakers closed in port, negating the redundant busses? I'm no marine electrician, but the power plants I work at don't operate with their tie breakers closed unless there is an issue with parts of the system.
Sounds like it could have been a short that was on the side that had not been used in awhile! There could have been a corrosive element in the LR 1 HR1 system. As someone who has captained 100’ vessels, this was the perfect storm situation. Losing power at the worst time. Normally when this size vessel is moving it is in open water, where this situation system fail would not have any tragic consequences! Great video as usual.
A lot of industries will alternate redundant equipment so that both sides get used unless one is broken.
I'm not familiar with modern switch over systems for 3 phase power, but unless the system automatically synchronizes the phases when the crew manually closed the breakers, (probably in a panic) an out of synchronization condition would instantly trip Gen 3 & 4 breakers. Still the cause of the first breakers tripping is the correct focus of the NSTB investigation.
#154 Thank You for a very good explanation. It appears that all systems worked as designed. Just not enough time to allow the systems to run their procedure. New improvements: Escorting Tugs to remain with ship through hazard navigation. Development of quicker system recycling. Also, scrubber damper in auto mode on all generator exhaust on a separate electrical circuit. I believe the crew did the best they could with the time that they had! A ship that big needs extra assist to move in tight areas. The Captain, Mates, and Pilots did the best and may have saved more lives---it could have been worse, much worse.
Very interesting! Most people had been speculating about engine/generator-related problems, but it turns out to have been an electrical problem. It’ll be interesting to see what the root cause was; it must have been a pretty major fault,
(I’d like to see the size of that main breaker connecting the two halves of the 6,600V bus together, I’ll bet it handles a load of current!)
What I found most interesting in the report is that the previous on shore blackouts seem indeed to be completely unrelated:
One was just caused by a mishap by a crew member.
The other was caused by insufficient fuel pressure for the generator that stepped in. Probably just because things were not configured for that gen to run or something.
Both events do NOT suggest, that there is generally something wrong with the ship, the generators or the electrical system.
Quite the opposite: The 2nd gen stepped in automatically after the first one stopped, so things worked as as intended.
From that I'd say the crew had no reason to belief the ship was not sea-worthy.
The only link to this event seems to be, that this triggered the crew to switch the transformer in use from No. 2 to No. 1. And maybe that one has some unknown issue/fault.
One mistake of the crew could have been to re-close the transformer 1 breakers after the 1st blackout, instead of immediately switching over to transformer 2, wich they used for the last few months. But in such a stress situation such mistakes can happen.
It reminds me of our natural reaction, when a circuit breaker in our home trips, our first natural reaction is to try and reset the one that tripped because "well, maybe it was a random accident".
These aren't "breakers" like you have in your house exactly. They do the same thing, but we're talking about 200Amp currents or higher. There's a procedure for energising a switch like this. Can't be that different from a substation. This is the best explanation I've heard to date, just don't know if you weren't there.
The weight of the ship plus the cargo on board is mind blowing.!! no wonder it knock the bridge over as if it was made out of cardboard boxes. just think about it in pounds... over 124,000,000 Lbs. of cargo, then roughly double that to include the ship!! I wonder the boat was heavier than the whole bridge. Great job Jeff.
Thanks Thomas!
Whens the video regarding the barge that hit the Pelican Island Bridge in Tx coming out?
On the electrical diagram the high voltage bus tie is shown closed. But the narrative of other breakers opening sounds like they were operating with it open or that there was some resistance across it. The report doesn't say anything about whether it was open or closed or tripped open. Both transformers would supply the low voltage bus if it was closed, but if it was open that isolates high voltage power to one of the transformers and defeats some of the redundancy for the low voltage busses.
i do believe the ship's system is designed to only have one set of the breakers closed during operations.
basically if they where both closed and one trips, all that extra load would go through the other one causing it to also trip.
Tie breakers on the HV and LV sides should not be closed in normal operation. Tie breakers are only supposed to be used when one side of a redundant system fails and there is a need to "tie" the sides together to provide power to the side that is down once it is determined why that side failed. With the two sides tied together a failure on either side will bring both sides down. If the diagrams you showed are correct, this system was not being operated correctly!
@@cranberrysauce61 Yes, that is exactly why the tie breakers should be open and not closed.
@@eagle2019 This is exactly my thought. Tie breakers closed makes me feel like there was something wrong with the systems, or they had an engineer that didn't think isolated redundant systems were important. Even power plants dont pull this, their backups have dc backups for their isolated ac backups.
I liked the NTSB report and went to their site and downloaded the PDF.
After watching the shape charge detonations on the truss, I was surprised they didn't break down the truss near the water, but maybe it is small enough for the hauled away by the crane barges.
Regarding a previous video where you pointed out a black panel van sitting at the edge of the bridge nearest the Dali that you speculate is blocking drone transmissions...
I don't think they would want to block any transmission because of all the work they are doing where blocking the wrong frequency controlling vital equipment could be disastrous....
A more plausible explanation is a listening post for gathering intel. I believe the van is there to listen to any and all transmissions including shortwave and cell transmissions in and around the Dali ship.
grea video. wonderful explanation, thank you alot
Remarkable that so much was done/tried is so little amount of time. Was the ships horn sounded? If so when? I can only imagine what the guys on the road crew were experiencing seeing that beast of a boat bearing down on them that night.
Thanks for the review.
It looks like the only thing the crew could have done would have been to use the bow thruster to push the bow away from the bridge pier, since they had the high voltage bus available again. That might have been enough to avoid the tragedy, but possibly not enough too.
Thanks for a long and comprehensive video.👍
Hats off to the crew for doing their best to recover power so quickly with multiple redundant systems.
However at 2.19 seems like a potential “Darwin Awards” candidate for a design that lacks overall lack failure mode analysis.
Protection of the main (and only) propulsion engine was more important than ensuring its continued operation or going into reverse quickly to save the ship from catastrophic collision.
10:55 Immediately after this occurred, there were a large number of people saying that the steering could never fail because it has redundancy. Well... When you assume.
It has redundancy if the switches and circuit breakers are set correctly, especially the tie breakers.
This tells a story of a crew that was fighting desperately to save the ship, and when it became evident that the crash was imminent, made a call to warn authorities, minimizing the loss of life.
Very interesting video and well explained.
One point of correction, however. In your explanation of the power failure while the vessel was still in port you said that after DG3 started the crew tried to close HR2 and LR2 but "there wasn't enough pressure" and that caused DRG3 to pop. This implies some sort of issue with the electrical system, which is incorrect.
In the report narrative it states that the crew members manually closed HR2 and LR2, but that Generator No.3 shut down a short time later due to insufficient fuel pressure. So the issue here was that the generator shut down due to a fuel issue, not because of an electrical issue.
"not enough pressure" implied to me that the actuators were pneumatic or hydraulically controlled. That's not particularly uncommon in industrial power systems.
@@miscbits6399 Yes, and that implication is exactly what's wrong with what was said in the video. You inferred that there was an issue with the breaker, but that's not what happened. Details like this matter if you are going to do deep-dive analysis of things like this incident.