Francis Scott Key Bridge (Baltimore) hit by Cargo Ship and Collapsed

walterjay said:
When you don't have power your rudder is pretty much useless.
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Having some sort of battery backup would have been nice. A lot of fly-by-wire aircraft do that these days, so if there's a loss of generated power, the batteries can still provide controls. Even if there's loss of hydraulics.

I wonder if this is going to create an incentive to create some sort of battery backup as a redundancy.
 
y_p_w said:
Having some sort of battery backup would have been nice. A lot of fly-by-wire aircraft do that these days, so if there's a loss of generated power, the batteries can still provide controls. Even if there's loss of hydraulics.

I wonder if this is going to create an incentive to create some sort of battery backup as a redundancy.
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Doesn't really matter with the big ships. If the propeller isn't spinning, the rudder has massively less control.
 
ctechbob said:
Doesn't really matter with the big ships. If the propeller isn't spinning, the rudder has massively less control.
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Why wouldn't the propeller spin? I get that the big diesel engine is electrically controlled, but I was thinking a battery backup could make up for a loss of generator power and power all the stuff that the generator would power. Of course a big alert too.

I lost an accessory belt once and it my engine and ECU were still running off the battery. That worked until the battery died. But it certainly would have been enough for several minutes.
 
y_p_w said:
Why wouldn't the propeller spin? I get that the big diesel engine is electrically controlled, but I was thinking a battery backup could make up for a loss of generator power and power all the stuff that the generator would power. Of course a big alert too.

I lost an accessory belt once and it my engine and ECU were still running off the battery. That worked until the battery died. But it certainly would have been enough for several minutes.
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These big ships have the propeller directly connected to the big diesel. They aren't electrically driven. If they need to go in reverse, they stop the big engine and start it backward. If the big motor isn't running, the prop ain't spinning.

 
ctechbob said:
These big ships have the propeller directly connected to the big diesel. They aren't electrically driven. If they need to go in reverse, they stop the big engine and start it backward. If the big motor isn't running, the prop ain't spinning.

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I get that it's driven by the diesel engine. However, the situation here seems to be that controls and propulsion was lost because of a loss of electrical power to control the steering and the engine. I was thinking maybe a backup battery could provide that until the generator is back online.
 
y_p_w said:
I get that it's driven by the diesel engine. However, the situation here seems to be that controls and propulsion was lost because of a loss of electrical power to control the steering and the engine. I was thinking maybe a backup battery could provide that until the generator is back online.
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I guess they figured that having a backup generator is enough? Backups for the backup?
 
y_p_w said:
I was thnking battery backups can come online a lot faster (and more reliably) than a backup generator. I've seen whole building uninterruptible power supplies come up with just a blip (like a short brownout) when they transferred over.
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A good friend installs industrial UPS for this exact reason. His current and probably all future projects are MS(Azure) Data Center builds. Huge ones with 25 megawatts of on site generating capacity.
 
Donald said:
It had 2 pilots aboard so knowledge of harbor was not a problem. People were on bridge fixing potholes and several fell in. Two rescued.

Another bridge in MD was refitted with bridge pier protection to prevent this kind of accidents. But not this one.

But it seems they were able to radio ahead and stop most vehicle traffic. I think an article said basically that.

Cargo ships don't have bow & stern thrusters like cruise ships.
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From a few articles this very ship had similar problems when docked in central America at its last port. If a major issue like this arises I thought there would be a thorough investigation, and a double check that is was repaired correctly before leaving. I know that the shipping industry operates similar to commercial aviation. You want the ship full, and as soon as it arrives to its destination you unload/reload and get to the next port. Delays cost money and can incur penalties.
 
y_p_w said:
Why wouldn't the propeller spin? I get that the big diesel engine is electrically controlled, but I was thinking a battery backup could make up for a loss of generator power and power all the stuff that the generator would power. Of course a big alert too.

I lost an accessory belt once and it my engine and ECU were still running off the battery. That worked until the battery died. But it certainly would have been enough for several minutes.
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It may not have an electric back up most big ships don't. It would need a pretty good size electric motor to turn to shaft. I am not sure how this ship is coupled to the diesel either. Reduction gears? Direct Drive? Most are direct drive. Also, with the amount of time they had I don't think they could have done much.
 
The "generator" everyone talks about also probably powers ship's service hydraulics, which should run the bow thruster and the "power steering" for the rudder. It would make sense to have a midsize diesel engine run all this stuff at a constant RPM while the big engine turns the prop.

I bet UPS/ battery only powers the most spartan stuff-- radio, navigation lights, radar. It's not turning the ship.

I'm disappointed the little engine was run on junk fuel while still in US waters but hey, profits, right?
 
k1xv said:
When railroads built their 19th century infrastructure, they spared no expense and built solid. Viaducts built to support 100 ton locomotives were holding up, no problem, with rolling stock 60 years later that weighed three or more times as much.

However, by the 1970s, when this structure was built, "over-built" meant "money wasted".
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My neighbor was a Golden Gate Bridge enployee in the engineering dept and when they replaced the suspension cables in the 1070s holding up the road way he said the original cables tested stronger than the cables the replaced. So he said.
 
ctechbob said:
I guess they figured that having a backup generator is enough? Backups for the backup?
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I was thinking the same thing, a belt, in case your suspenders break? What is this battery backup that we're talking about. Usually that term is used in the computer/server world. It provides enough juice to gracefully shut down equipment, less so to continue using it.

First of all, is there such a thing? I would think not as far as taking the place of a generator. Is it a giant Gooloo or something?
 
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