Yes fully agree KC.
Sorry if I misunderstood your earlier post
Yes, they had two DGs connected on the same switchboard, not an issue during the accident. The problem was tripping of the only connected transformer. That stopped all the circulating pumps and fans and shutdown the main engine. When power was restored all these auxiliaries were supposed to restart automatically, provided they were kept in Auto mode and that they were operational. The information overload is another issue here, during the blackout they were probably hundreds of alarms going off.
The issue with steering gear pump No.3 not running when EDG came online is intriguing, although I personally never seen a ship built in Korea with 3 steering gear pumps, only 2 or 4.
Let’s not forget that with the propeller stopped, the blades act as rudders themselves…
How many blades does the Dali’s prop have?
if it is a RH prop, and one blade stopped near the bottom, could it help turn the ship to starboard?
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KV
Apparently 3 pumps is not uncommon
In my experience this effect would be negligible.
Environmental factors have much more effect ie the weather vaning of the wind acting on an aft accommodation block, fairly predictable, but with the Dali and her likes the effect can be very unpredictable without a distinctive large sail area like a tall accommodation block.
Container distribution can dramatically change the handling of ships particularly in higher winds
Interesting that the design for the Dali fed the ME lube oil pumps off the HV BUS yet the ME cooling water pumps were fed off the LV BUS. So, technically, the ME was still being supplied with lube oil after the first blackout yet the loss of the cooling water pump automatically shut down the main engine.
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Aus
Where do you see this? Very unusual to have HV motors in the engine room.
“The generators were connected to a 6,600-volt high-voltage (HV) main electrical bus by the vessel’s power management system (see figure 3) that powered various shipboard equipment, including the main engine lubricating oil pumps, the bow thruster (a propulsor on the ship’s bow that that assists with ship maneuverability), and reefer containers”.
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Considering the size of main engine, the lube oil pumps are also very large, so having HV motors makes sense, reduced current and smaller cables.
Interesting. The lube pressure is one the items that cannot be overridden to restart the main engine. The other being the thrust bearing temp. Cooling water can be bypassed. But with possibly no power to the hydraulic pump and engine electronics they could not have restarted.
thats another issue as they should be on the EDG
I would not be surprised if the HVR breaker was installed to manage the short circuit rating of the board. That is it cannot handle all generators on the board supplying full power to all the essential eqpt through the LV board and the reefers and the BT. It is a definite deficiency if this is the case. Selecting high performance breakers with the correct response time perhaps adds a lot more cost.
Installation of the LVR is a mystery. Serves no purpose really.
Not known for sure when the EDG come online. Crew says it was when the power went out the first time but NTSB report says that was not confirmed.
From page 11 of the preliminary report:
When the emergency bus was powered, emergency lighting, navigation and radio equipment, alarms, and other emergency equipment would have been available, and the designated emergency steering pump (no. 3) would have been available to turn the rudder at its low-speed setting. (When operated alone using emergency electrical power, steering pump no. 3 was designed to run at a lower speed, turning the rudder at a slower rate than with all pumps.) However, without the propeller turning, the rudder would have been less effective.
If memory serves, the ship I worked on the steering pump that ran off the emergency bus would start automatically when the EDG came online. Don’t know if that’s the case on the Dali.
On the steering system that I have experienced on a HHI built tanker (VLCC) had 3 pumps. (Same vessel with the hydraulic lock and damage to a ram pin on one fork of the tiller mentioned earlier). 1&2 serving hydraulic system 1 and No. 3 serving hydraulic system 2. Pump 3 was powered from the ESB. All 3 pumps/motors same size. Each pump independently designed to meet regulations of 35-30 in 28 secs. Generally for maneuvering 2 pumps are in service – any combination that probably gives speeds of at least 1.5x of regs.
Possibly on the Dali similar arrangement. Unusual they had all 3 operating at departure. Note: Operating all 3 is not restricted – but doubt if the response speed is any better than operating 2.
Agree - but also to add to above rudder power increases when engine speed is greater than ship speed, and decreases when engine speed is less than ship speed
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So now the mystery is why the vessel did not respond to rudder commands. Possibilities I can think of:
- Pump was worn out/defective and not noticed by the crew as possibly never operated on its own
- Pump was not restarted after blackout from the wheelhouse
- Hydraulic lock.
- Motor or system needed a simple reset.
Also to note, the steering flat will be unmanned – and quite a ways away from the ECR.
from SOLAS: .1.3 where the main source of electrical power is necessary for propulsion of the ship, the main busbar shall be subdivided into at least two parts which shall normally be connected by circuit breakers or other approved means; so far as is practicable, the connection of generating sets and other duplicated equipment shall be equally divided between the parts
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KC,
Surely, the steering pump which is fed off the emergency bus must seamlessly and immediately energise when the EDG comes on line.
The sanctimonious amongst us will reiterate the reminder that this is a “preliminary” report yet there is some essential information missing which would be currently available to the NTSB.
- The entire bridge team inclusive of both Pilots, Master, Duty Officer and helmsman would have been fully interviewed.
- The VDR audio wheelhouse recording was uninterrupted by the blackouts.
Surely, from both the above sources, it could be easily determined and reported regarding helm inputs and steering gear outputs. Plus, the inputs and outputs would be accurately time stamped by the VDR.
The Pilot’s helm orders would be verbalised and the closed loop communication from the helmsman would be verbalised. I have worked with many Indian bridge teams and their closed loop communications have proven to be first class.
Intriguing.
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agree, of course But from the report the ship was on the channel course approching the bridge with rudder amidships - makes me think enviormental factors were not that great. Would be expecting them to be carrying some rudder if being acted on in any significant manner by channel hydrolics or wind/tide
Does it apply to a diesel propulsion? Really meant for pod or azimuth thruster propulsion where the main propulsor is electric motor.