Oh well, shit happens. Everyone is scared of high river…for a valid reason. They will fix it. No one wants to do what they went through
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Looks like nice clean bright wedges to me.
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Yeah when I looked closer I figured such
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Touch me there again and I will scream!
Isn’t this one of the new eco class ships with the funky engine load program designed so you don’t overload the engines?
How does that system work? Can the bridge override the system? What happens if they do?
A post was merged into an existing topic: Letting go / Making Tugs Fast
I don’t know about this class of ship but if it’s similar to the low-speed diesels I’ve seen (max about 100 rpm) it would have a load-up (and load down) program to allow the engine to warm up slowly to avoid thermal stress. From dead slow to full maneuvering (full harbor speed 12 kts is typical) there is no program, engine changes rpm in response to orders. Above full maneuvering the program controls the increase.
The program can be overridden from the bridge, slowing down the rpm will drop quickly but speeding up it’s a matter of hp and mass. In my experience you might get a few extra turns, less if the wheel is hard over.
I don’t imagine they were using the load program right after having let go and topped around. Typically when outbound and above the city, especially with the river running as hard as it is, I would be surprised if the pilot wanted to load up at all. Once south of Algiers Point they might hook it up, but the program can always be canceled instantly from the bridge.
From the context I took the question to be would the ship’s load up program limit the ship’s maneuverability at low speed? For example if more rpm was needed to increase ROT.
Because there is a program by-pass the limit would be actual horsepower, not a limit imposed by the program.
Ah. Then you are correct. The load program only kicks in once going past Full maneuvering to Sea Speed.
To answer @john’s question, yes the bridge can override it and bypass the load program. The Chief might be pissed about it though…
Yes, it can be overridden on the bridge. The Captains expect it and it is no big deal. Without the override, you really don’t have much go go until the program gets going. The class is notorious for this odd characteristic.
After days spent at other Tampa spots, ‘American Liberty’ went into dry-dock at Tampa Ship, yesterday.
They probably had to discharge whatever product they were carrying.
They would have to have done something more secure to seal the gash in the hull than the damage control wedges before sailing.
Buck Kriehs probably patched them up before they even left the river.
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I took that from the context as well. I’ve only seen load program being in effect for bells above full ahead maneuvering up to full sea speed. However, I was PM-ing with another member who works on one of the Eco Class ships and he said:
“We run the 6G50ME-B. 7200 KW at 88.9 RPM. Slow turning, big big props.”
With a really big prop, I could see the automation imposing a thermal load limit at bells even below ahead full. If that’s the case, I would be surprised if the automation would allow an override of that limiter without input of a code of some kind (i.e., in a real, no-shit emergency as opposed to standard operating procedure every time you maneuver) as this scenario would actually overstress the engine and risk doing damage.
I’m pretty certain that there is a load program between bells on the ME-C’s. I can’t remember the exact wording that appears on the main engine automation MOP, whether it’s ramping, loading, or something similar. It goes very quickly and is only noticeable if you’re watching the screen when you get a bell to increase rpm.
Most engine rooms that I’ve sailed with extensive automation have had limitation override buttons in the control room for the oh-shit emergency moments. We also had shutdown and slowdown overrides. IIRC, the only thing we couldn’t override was an overspeed of the main engine. I can’t recall if they had the override buttons on the bridge as well.
The ship you have seen this on, is it the low RPM, long stroke (G series) engine with the large prop? That’s the only thing I’m thinking is that these ECO’s with their very large propeller, it would be easy to get to the left of of the load limit line if the engine tried to accelerate too rapidly. And thus, I’m sure MAN would have limiters in the automation to prevent an operator from overstressing the engine.
This setup is good for fuel economy at sea speed but would require different tactics for a bridge team who are used to being able to dial up ahead/astern bells at will on the ships with a smaller propeller and (relatively) higher RPM model engines.
Page 14ff may be of interest:
Acceleration Issues for ME-C/ME-B
Mk 9 – S and G Type Engines
Lately, low acceleration capability has been experienced on some S50MEB8.2/9.2 engines installed on ships with high-efficiency propellers operating at a relatively low rotational speed. The root cause has been identified to be a low excess air ratio (air for combustion) at low load and heavy running especially during the acceleration phase. This is due to the application of two-stroke Miller timing with late closing of the exhaust valve.
https://maredu.gunet.gr/modules/document/file.php/MAK330/ME-C/service-experience_ME_Engines.pdf
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