Yours noted. Then what is your interpretation of pdfs included in
comment 226, 227 , if my interpretation of what is contained there is wrong as per yours:
Capt KC - what does this mean? You typed in the text in bold and the response follows from ChatGPT? Scary if yes.
While I was trying to find some info on the Steering Gear similar to the Dali with the 3 pump configuration, I came across the attached from ClassNK (Dali Class society). Looks like the hydraulic lock is a recurring event to prompt them (and IACS) to revise the rule requirement.
https://www.classnk.or.jp/hp/pdf/info_service/iacs_ur_and_ui/ur_m42_rev.6_mar_2022ul.pdf
- Operating instructions
Where applicable, following standard signboard should be fitted at a suitable place on
steering control post on the bridge or incorporated into operating instruction on board:
CAUTION
IN SOME CIRCUMSTANCES WHEN 2 POWER UNITS ARE RUNNING
SIMULTANEOUSLY THE RUDDER MAY NOT RESPOND TO HELM. IF THIS
HAPPENS STOP EACH PUMP IN TURN UNTIL CONTROL IS REGAINED.
The above signboard is related to steering gears provided with 2 identical power units
intended for simultaneous operation, and normally provided with either their own control
systems or two separate (partly or mutually) control systems which are/may be operated
simultaneously.
The other interesting piece of info that I came across is that Yoowan machinery (Korean manufacturer of SGs) provides an option to start the SG pumps on ‘no load’. This provision is to limit the start current on the emergency bus. A ‘no load’ start on a hydraulic system most likely will be solenoid operated from the discharge side of the pump to dump all the oil the back into the atmospheric reservoir (no pressure build up) and after a few seconds the solenoid (possibly energize to close) closes and builds up pressure. Maybe Dali is equipped with this feature and this solenoid malfunctioned. Possible also a wiring error where this solenoid on the pump 3 was wired/powered from the main switchboard that was mostly black.
1 Like
You Sir are damn good in research. 
You all know ChatGTP is prone to make up random bullshit, right? This is only going to get worse as it trains on websites it created in a circular doom loop.
1 Like
Kennebec_Captain posted a AI-generated summary of my (too) long post. 
It would be tempting to write a silly reply just to see how the AI would interpret it. I bet randomly chosen topics will appear in the summary simply because AI will not be able to tell the difference between more or less relevant details, and especially not in a technical context.
Indeed AI is unable to interpret graphics like complex wiring and hydraulic diagrams, also many details I mention in my replies are based on my own experience. AI probably works well for journalism, legal matters and other domains which are heavily based on non-technical texts with huge amounts of crawler-searchable data available online.
OTOH when it comes to very specific technical details it is often impossible to find any documents, therefore AI will very often not even be able to retrieve any useful information.
Though as seen above, AI can be useful to generate the base of executive summaries which can than be tweaked manually. The same applies to translations. Remains the questionable objectivity of AI but that is another topic, AI is biased (e.g. woke and politically correct).
Paraphrasing is not that difficult as long as no more advanced interpretation of the content is required.
The Yoowon ram-type steering gears are licensed Mitsubishi steering gears
There are small detail differences between the different steering gear models, also the way several pumps are operated in parallel can vary. Large ram steering gears usually feature 2, 3 or 4 main pumps, each driven by an electric motor as well as the same number of auxiliary pumps unless these pilot oil pumps are driven by the same motor as the main pump (usually mounted coaxially behind the associated main pump).
Also pilot oil controls vary as well as unloading solenoid valves.
For larger container ships with single ME the power of the main steering pumps are in the range of roughly 3x120 to 4x250 kW, depending on the emergency generator the starting method of the corresponding pump can be different as it is the case for M/S Dali (4 cylinders, 3 pumps with pump #3 not being started DOL when supplied by the EG, see PR).
As typical example, with a 4-cylinder 4-pump steering gear, 1, 2, 3 or 4 pumps in any combination can be run simultaneously with all 4 cylinders operating in each case and each pump combination. Restriction apply in case of failures (usually 2 cylinders of the same ram, not diagonally). On emergency power only one predefined (i.e. always the same) pump can be operated (with all 4 cylinders operating).
Unless there is a design oddity like for M/S Dali, the number of simultaneously running pumps only influences the reacheable angular speed of the rudder stock but not the maximum torque.
The effectively required torque is determined by the force applied on the rudder and varies permanently when en route.
With the unloading valve in bypass position and/or the variable symmetrical displacement main pump hold around the zero displacement point, the motor can be started with a low torque load.
An auxiliary pump driven by its own motor must start shortly before the corresponding main pump.
Unfortunately the controls are very basic, it would be better to use redundant PLC’s and also monitor all pump speeds with rotary encoders, especially as some faults can cause pumps to be driven in reverse (electric motor not energized but driven by its pump in the wrong direction).
The so-called safematic function could be handled by automation with redundant reserve oil tank analog contactless level measurements.
As the steering gear is mission-critical it should be monitored much more efficiently and also CCTV monitoring should be included (later even vision could be added to detect some failures).
To avoid problems due to ingress of air, a steering gear should be run shortly daily (excepted in dry dock of course).
Can someone explain this “air in the steering gear” issue? I’ll admit the largest rams I have ever worked on fit in the back of a small pickup, so maybe I am missing something, but they had a hose at each end and no air. The pump(s) moved fluid from one side to the other and back again, as long as we bled the system and didn’t have bad connections they never got air in them no matter how often they got used or not used.
Not so fast Alias Steamer.
Some with the longer attention span
may be interested in reading this SHIT.
You need mods to block??? Leave them alone, they are already overloaded.
Here is an instruction manual how to block and /or ignore shit content
@ yacht_sailor:
I already replied about air in hydraulic systems. If you do not believe me, please ask a hydraulics design expert, i.e. someone who really designs complex systems, incl. true servohydraulics not just basic routine work. I do not design hydraulics myself but have designed and commissioned the control part of servohydraulic systems.
@ spowiednick:
You are fully free to disagree with me but please let me know precisely where I am wrong.
Please feel free to report my posts but if doing so you should also explain clearely why and prove where I did mistakes.
I suppose you know how the safematic system works and how it caused problems in the past, as well as how exactly the steering gear is controlled, both manually and by the autopilot, and not just the basics. Or how a large bow thruster works in detail including its control interfacing.
Once again it is important to refer to very large steering gears and bow thrusters like the ones of large container ships. Also the ME type is important as some generic comments may no apply and even if the already mentioned engine type is known, there are still further option variants which play a role when discussing some details.
A constructive discussion is welcome but just criticising without adding anything useful leads nowhere. I respectfully invite you read again my long posts once the final NTSB report will be availble.
I will not spam the board with many small messages, those interested can read my contributions but I have no problem with those skipping them. Some details I mention cannot be found elsewhere, I will let you do an extensive search and ask your AI helpers.
And no, I do not use any spell checker, I am not a native English speaker but OTOH I speak the two major European languages without any accent. If I had to chose I would still keep my 2 1/2 languages instead of becoming a monoglot native English speaker.
The steering gear you are used to typically uses a “helm pump” with a built-in reservoir of hydraulic fluid. That pump is directly driven by the wheel and is mounted at some height above the steering ram(s). In effect, that means there is a positive pressure head on the cylinders at all times so any leakage past a seal on the rams will simply drip into the bilge until the pump reservoir and the tubing to the cylinder are empty. The steering pump and its header tank (if fitted) will drain first and the pump will be unable to produce flow or pressure to the rams even though the rams might still be full.
Ship steering gears use a large hydraulic reservoir (tank) normally mounted lower than the rams and vented to atmosphere. The pumps take a suction from the tank and the cylinders normally return oil to the tank. Any air that might find its way into the system (from maintenance usually) will be removed during normal operation. Even though mounting the cylinders higher than the tank means they are under less than atmospheric pressure when the gear is not in use it would take a very leaky seal to let much air in. When under operating pressure that seal would probably have a very obvious external leak.
1 Like
I am not a native speaker too and i can handle only 1.0009231 of European fringe languages . With regret I must observe You did not catch my drift . So instead of giving me some long dressing down read my comment again and may be again and if still in doubt what it meant send me PM whith a simple question" what the hell do You mean Spo as I am not sure I get it ??? " . I would be only happy to uncover the meaning of my comment. Meantime take a chill pill and relax buddy 
Cheers and have a wonderfull rest of your day
Wonder what we can call the rest of the above message.
This thread was great for a while but has devolved into incoherent rambling.
It’s so bad I am waiting for the Coulumbi Egg inventor guy to show up and start writing essays of his own. Surely this thread will summon him…
1 Like
Yeah Slick,
Bored with this now
Time to try to figure out how to log off,
Maybe AI could help 
Power of compounding. Works both ways – up and down. Aside from possible equipment such as SG failure after blackout, contributory factors under crew control outlined below.
First lapse. Departure port. Only 2 DGs on the board with the BT on. Why on earth would you not have another DG on irrespective of the possibly low load operation on the DGs? Is this saving fuel/running hours per the company (possibly verbal) directive?
Second. At the first blackout. Why does it take a whole minute and then some to close the upstream and downstream breakers for TR1? BTW, I think these transformers are not configured for a ‘hot standby’ condition where the other transformer would come on line automatically. Possibly by design to avoid potential HV harmonics if accidentally both are in service.
Third. Looks like the DG2 had started. Why did they not start initiate the synchro sequence to get this on the board? Press of a button. Surely they had an idea that something was FU with the fuel system on DG3 and 4 room or other to have the event above …fuel issue similar to what they experienced in port? Auto back flush filter? Synchro DG2 and also start DG1.
Fourth. Soon after the first blackout and LV power restored, their priority should have been to see if they could start the ME – either direction per Bridge command. Astern at that speed should not have been a problem (provided the air bottles were fully charged … no indication otherwise).
Fifth. Engineer(s) who was/were off watch should have been summoned at the first blackout to assist. (Maybe they did). One of them should have raced to the SG flat. No idea if this was the case. On the SG setup, looks like pump 1 powers hydraulic unit 1 and pumps 2 and 3 powers hydraulic unit 2. Hydraulic unit 1 with pump 1 should be capable of the 35-30 in 28 seconds. Hydraulic unit 2 with both pumps 2 and 3 should be designed for the same. With just pump 3 the regulatory speed requirement is 15-15 in 60 seconds. Assuming the EDG came on line within the 45 secs with pump 3 and LV power was restored about 15 to 25 secs after that with pumps 1 and 2 starting, would it be conceivable this created a hydraulic lock? Possible.
Sixth. DG2 was put on the board (possibly by closing the generator breaker as the HV board was black - no synchro required) only at the second blackout. And it took more about 30 seconds to restore power to the LV board by closing the TRI upstream and downstream breakers . BTW, this is a clear indication that both these breakers are equipped with a UV coil and will open as soon as there is no voltage upstream. So the first blackout could be a momentary dip in voltage due to fuel or other trouble that drops out the UV coil in the upstream breaker of TR1. Again no indication if they started the DG1 at this second blackout.
From the video, looks there was a third blackout as soon as contact was made with the Key bridge. Possibly this was just the breaker tripping for the deck lights.
Love some of the alias’s people have chosen …
1 Like
Only if you want a multipage dissertation on the history and comparative quirks and operating techniques of web browsers.
1 Like
I think the above is incorrect.
More like pump 1 and 2 powers hydraulic unit 1 and pump 3 powers hydraulic unit 2.
2 pumps (any 2) are required for the 35-30 in 28 seconds.
Pump 3 on the emergency bus would meet the regulatory speed requirement is 15-15 in 60 seconds.
All 3 motors likely are the same electrical rating
Pump 3 may also have an unloaded start feature … with a time delay of 5-7 secs for the auto pilot/steering stand to respond to helm commands. (maybe about the same time the main power was restored briefly before the second blackout)
Too many little electrical contacts that probably never gets tested.
Hello – I have a question for the Pilots and Captains.
Would you feel comfortable maneuvering in congested waters if the SG reverts to the slow speed (emergency) setting of 0.5 deg/sec as opposed to (usually) better than 2.32 deg/sec?
I am assuming not and that you are not aware of the slower speed allowed by the rules. In my mind, as Capt and Pilot you expect (and rightfully so) the engine and SG to respond to your commands. Curious if any of you have maneuvered a large vessel (say about 100 dwt) at slow engine/vessel speed on the slow SG and if the response was shall we say ‘surprising’ at best and ‘unacceptable’ in the extreme.
On the Dali, it may really not matter …. as there is a distinct possibility that the SG was frozen/hyd locked perhaps after the rudder returned to about midships after the EDG came on line.
What if the SG was on the ‘slow bell’ on the MSC Michigan with all those turns? Wonder if the outcome would have been the same.
Regulations/Rule development are based on experiences while keeping safety as the primary consideration. I think IMO/Class goofed up and most likely this arrangement is not well known among the operators (Capts and Pilots).
This regulation/rule needs serious consideration for a review and possible revision. Meanwhile, quite sure there are many owners/yards/vessels that have taken advantage of this on the large container ships and tankers – and calling on port around the world without tug escorts.
Thoughts and/or any feedback will be good. Thanks.