Yeah the Dali is a very normal container ship similar to the MSP fleet but a bit more TEU, the Triple E seems like about the only place you’d see the dual shaft gens and TG Ausmariner posted the diagram of.
That design was the result of pursuing the best fuel efficiency, the added redundancy was the result of a careful design. I would be very interested to see the diagram of these new 24.000 TEU vessels, I wonder if they are operating with just one transformer for the ship`s load.
One thing to note here: usually the HV and LV breakers for the step-down transformers are interlocked. If HV breaker trips, the LV would be opened automatically. And if the LV breaker trips, the HV breaker would be opened automatically. So technically the fault could have been originated on the LV breaker as well.
The NTSB is pretty good with finding mechanical faults, but lack shiphandling experience so that part of their investigation is usually weak.
Thanks 118
That goes a long way to explaining some of the strange terminology in the preliminary report.
For 244, AusMariner and others who have written about rudder effectiveness or lack of it.
First of all, all rudders are not created equal. To say a ship one served on could steer down to 3 knots is well and good, but I have had ships that would immediately begin to run to port or starboard when the engine stopped and hard over may or may not check them up at 6 knots. We don’t know if the Dali was blessed with a large rudder or cursed with the smallest piece of steel the shipyard could get away with.
Bank suction is a big factor in harbor piloting. When the channel is regular and even the forces on the bow and stern are balanced when the ship is in the center of the channel. If the channel opens up on the right hand side, the ship may be in the center of the marked channel but she is no longer in the middle of the navigable water. The forces are no longer balanced. This was the case of the Dali as she passed buoy #7. With the hydrodynamic pressure on the starboard bow going away the ship began to “smell” the open water. There was a force acting on her making her go to starboard.
Whether the rudder, with its reduced effectiveness, was strong enough to bring her back to port is an open question. Finding out what the rudder angle was at specific times gives us only part of the picture.
OneEighteen,
I think it is fair to say, in this instance, that during this incident the functionality of the steering gear and any sheer as a result of bank effect are of secondary importance. For a very short period, the bridge team and deck crew became mere spectators to a developing disaster. Nothing could be done with the hand they had been dealt.
I question the unnecessarily high transit speed and lack of tethered escort towage although that may be flagged as a recommendation in the final report.
The primary issues are there was no propulsion allied with degraded rudder efficacy……at high speed……over a very short and intense 4 minute period.
The fact that both outward and inward vessels have historically transited under the Key Bridge at high speed might inherently indicate that bank effect was not a major issue. The channel crossection is somewhere between unrestricted and semi-restricted which indicates that water velocities past the vessels are relatively low and therefore the high and low pressure systems enabling bank effect are relatively weak……IMHO. Happy to be corrected.
All very valid points 118 and I don’t know just how much effect the adjacent channel would have on the vessel.
I think I said earlier in this discussion that I have piloted one of Dali’s sisters, however it was a long time ago and only once. The act was memorable due to other factors than the handling of the ship which it is why it has stuck in my memory as opposed to the many many ships of similar size that have long faded into the past.
It was a flood tide approach with a 2 to 3 kts current behind us. We have to make a 60 degree turn and get straightened out just 2 to 3 ship lengths before the berth so we consequently have a relatively high approach speed as we have to power around the bend. Prior to this bend we do bleed the speed off until the rudder loses authority then apply power to make the bend. I don’t remember having any trouble bleeding the speed off with the engine stopped on the approach to the bend so I don’t think there is any problems with the handling of the sister that I did.
The reason it sticks in my mind was that due to the positions of the gantry cranes I had to make a last minute change and berth stern to tide as opposed to the swing I was intending to make. Stern to tide berthings were not common but were done on occasions but were planned in advance. I took a snap decision that although too fast and out of position for a stern to tide berthing I could achieve it safely in the benign weather conditions on the day Which I did. The alternative was to berth head to tide then either myself or another pilot to turn her around later. She was quite large for that particular terminal and the gantry cranes would not have passed the bridge wings and the terminal had planned for a starboard side to berthing on the previous tide that had been cancelled.
Aus
You typed that as I was typing my reply.
All good points and yes I do agree that the crux of this matter is the loss of power which is an engineering discussion but also the lack of tugs transiting a known vulnerable bridge.
I was just using my experience of a sister ship to say that I don’t think The Dali was a particularly difficult ship to handle.
244,
Thanks for your response and I certainly appreciate the complexity of your berthing. Always interesting with a following strong current.
I wonder if the loss of steering has triggered the Emergency Steering procedure, that is sending an engineer to the steering gear room and control the steering locally following orders received from the bridge by telephone.
The way that description is written, one might also assume incorrectly that the reefer compressors were supplied with 6kV power.
Indeed. They are normally 440V units so, perhaps, there is a separate transformer(s)/feeds directly off the HV board totally separate to the LV BUS.
You might well be right, but I can’t get there on the bank cushion argument.
At 0125 the ship is on the channel course at 9 kts and rudder amidships. So at that point, as you say the options are either the hydraulics are balanced or they are weak
At 0126 - left 20
At 0127 - hard left
Even with the channel opening to port, I have a really hard time getting comfortable that with 7-8 knots going over the rudder for 2 minutes it would appear to have no turning moment to port at all
That is a lot of environmental and hydraulic effects popping up in a minute or two
All things in the fullness of time I guess. But at least for now, I can’t overcome my skepticism about bank cushion or weak rudder response as the reason for the turn to port.
So what do you think caused it then Texas?
Personally I don’t have a scooby 
Initially I thought it was caused by the engine running astern but that has been ruled out.
Just a thought.
Some may not understand the reference to Scooby.
Cockney rhyming slang.
Scooby Doo ,- Clue
Same, and love the cockney rhyming!
I am skeptical that any left rudder was ever applied. But we need some more information from the investigation to know that.
Other option is I am 100 percent wrong.
All things in the fullness of time-
Yes there are transformers, plus a bunch of power factor capacitors, normally down in the tunnels.
The idea of 6kV extension cords between outlets and reefers is truly frightening! Having been “tickled” with 440/480V while tracing wet cords to troubleshoot dead reefers after a they were submerged during bad weather gives one an enhanced respect for electrical power on deck.
244,
Big stab in the dark so to speak……
Following the first blackout at 0125 the COG remained reasonably stable.
The blackout speed was around 8.5 knots and as the vessel approached the Curtis Channel entrance she started sheering to starboard.
SOG increased to 8.7 so it is safe to say she was not stemming a flood tide and she further sheered to starboard as she traversed the throat of the Curtis Channel entrance.
My understanding is that the tide was ebbing at 0125……ebb tide acting astern of the pivot point at 8.7 knots….sheer to starboard.
Stab in the dark. Having said all that, the range is only one foot around that location which would not indicate a particularly strong tidal flow.