Just saying .
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Based on a few thousands maneuvers on the meter, the tug induced very little turning moment but amplified substantially the barque backing speed.
That said, the tug never cast off her hawser of its own will and responded to the emergency to the best of its ability with the equipment provided and the orders received. The ending would have been quite different if a Z-drive was called out. She would have speed out and pushed right on the barque stern at any angle. I can testify that tugs’ captain save my life on more than a few occasions. Safe harbor shiphandling would just be impossible without their expertise, talent and passion!
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I think it is just the camera adjusting focus. There was someone with another phone who came in the screen and the camera seemed to focus on their phone vice the ship.
No one has mentioned (in the comments I’ve seen) about testing the engine ahead and astern before casting off. Isn’t that a standard practice? It’s certainly possible to test the engine and still have it fail, but no one has even asked if it was customary in NY or not.
Comment #189 by @freighterman1 .
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Here are the Charles D’s particulars
Approximately (with nozzles) a 20 tonne BP at 100% MCR.
Yes and yes. In most cases I would have simply said that the regulations required the anchor to be manned, but if I actually expected to use the anchor I would have asked them to run one out hanging free. The image of a Maersk mate and bo’sun pounding on the anchor chain with sledgehammers as their ship slowly drifted into the ship I was on (moored) was firmly embedded in my mind when anchors were discussed.
In this case I probably would have run the anchor out a bit given the current, proximity to the bridge and the gift of hindsight.
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It’s required by law, so why wouldn’t it be done?
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I was always asked before arrival that I had tested the engine before arrival in US, European and Australasian Ports. The engine was blown over on air and tested ahead and astern before departure. The printout recording the action was preserved and a logbook entry made.
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I’m not too sure about your vectors. I can’t do this kind of graphic display on the computer, so I’m impressed, but my experience of driving a tugboat conflicts with your representation. It seems like you added a vector twice and a tug has a hard time having any effect whatsoever as the assistee gathers either headway or sternway without a line up. I don’t think the tug added to the sternway much at all.
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I agree. I was in a kind of hurry when I draw it and didn’t have time to correct it. What about that one …
Note: CPP resultant thrust = Tug thrust
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KemalPamouk,
With respect, at the stage of this particular photo, the combined unit was making approximately 4 knots astern. For a tug to remain alongside without a line up it had to be pushing up to a certain degree and therefore must have imparted a sternway vector. The magnitude of that vector is hard to determine.
Edit: Putting the CPP/mechanical issues to one side……failing to have a tug line up (in an effective position) was absolute folly and amounts to human error.
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I am seeing conflicting specifications……from the link at post #266 it is 1800hp and from my own research, it is 1800hp yet yours is the second reference on this thread to 2800hp. A little confusing. She is running twin Cat D-398’s.
Edit: My apologies, you are quite correct. She has been re-engined with Caterpillar 3512’s which brings her up to 2800hp and a 25 tonne BP (with nozzles).
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I agree that it looks like they’re making 4 knots astern. If the tug had any hope of staying alongside, they’d have to either 1: Have a line up and twist against it to try and keep a 90, which they didn’t. 2: Push hard with hard right and hope your bow pud is nice and sticky, which doesn’t seem to be the case. If the Charles D. was pushing hard with hard right, that ship would have hit the opposite bank bow first. 3: Do a heavy walk to port and try to keep up, which seems to be the case. I think the flanking rudders would have helped with this. In any case, without a line up, the astern vector has to be pretty small.
Why don’t we see if we can find some ways to overthink this with calculations, charts, and graphs, before we even know the pertinent facts?
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One key piece of information would be when did the bridge team on the Cuauhtemoc realize what was happening? Air France flight 447 dropped in a stall for about 3 minutes and 30 seconds. (AF 447 is not the topic of this thread) It was only understood what was happening after it was too late.
There are several case studies at this link: Standards for handling Controllable Pitch Propeller failures - what they have in common is that the crews involved did not understand that there had been a failure in pitch control.
On this thread there apparently is an assumption the crews on both the ship and tug understood the situation. I don’t know if that assumption is justified or not.
For example did the tug crew expect that the ship would continue moving astern or did they expect it would move ahead?
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A post was split to a new topic: Horsepower units
