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Baltimore's Key Bridge struck by cargo ship, collapses

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Re: Baltimore's Key Bridge struck by cargo ship, collapses

#671

Post by bmitc »

boringg wrote: post #375
makach wrote: post #70

Earlier quoted context omitted.

Modern bridges are required to endure a collision. This bridge might be very old and not sufficiently maintained against current requirements.

Collision means nothing without magnitude of force. A glancing blow is completely different from a direct hit. And the amount of Newtons behind the blow completely changes the outcomes. A small ship versus a loaded container ship is a completely different force. I doubt many bridges would take a full speed, fully loaded container ship directly to one of their supports and survive it. Certainly the most celebrated bri…

Apparently this container ship was only half loaded to capacity. And it seems likely that a container ship would hit it given the vicinity of such container ships. I'm generally confused on this matter.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#672

Post by refulgentis »

thekid314 wrote: post #597
paddy_m wrote: post #568

Earlier quoted context omitted.

On ships like this the propulsion is separate from the steering. There is a separate rudder that is close to, but not attached to the prop and propshaft. The propshaft is fixed. The rudder doesn't just "restart in a random position" it would remain in the previous position unless there was a physical piece that broke in the rudder gear. The fact that ship was able to reverse hard ( as evidenced by the slowdown), indi…

Was there a harbor pilot on board, or the normal ship pilot? Were there tug boats helping with the exit? I have often felt that the harbor protocols were overkill, but this is one of the times they could have helped.

2x harbor pilots.

No tugs.

Harbor protocol was in effect.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#673

Post by esaym »

jcgrillo wrote: post #555
araes wrote: post #541

Earlier quoted context omitted.

Current personal suspicion after watching your linked video (excellent discussion by the wgowshipping author) is: Catastrophic engine failure (1:24) causing wide scale power loss. No rudder control, rudder drift, and ship alignment drift (1:24-1:25:30) Power restored and ship reengages prop with bad ship/ruddder alignment (1:25). However, ship is now pushing itself into a further bad turn. Pilot likely stomps the bra…

I'm not sure what configuration of props a ship like this has, but in my experience with a 40ft sailboat with a single propeller you have absolutely no rudder authority while reversing. I've read that some large ships also are direct drive--there's no transmission between the engine and the propeller, so "reversing" (if it's even possible) entails shutting down the engine and restarting it in reverse. This can be don…

>entails shutting down the engine and restarting it in reverse. This can be done with a two stroke engine.

Funny, I was starting a 2 stroke chainsaw a couple of years ago. I yanked the cord, it kicked back, pulling my arm back down but the saw started up and ran anyway. But it would not cut at all. I killed it and restarted it and noticed the chain going the other (right) way and it was now cutting fine. It has started in reverse the first time!

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#675

Post by paddy_m »

mcv wrote: post #616
wlll wrote: post #573

Earlier quoted context omitted.

> in my experience with a 40ft sailboat with a single propeller you have absolutely no rudder authority while reversing. In general it depends on the rudders and the boat. Longer keeled boats don't respond well in reverse at all but more modern boats (like mine, 1990) will do better but will still need some way to have steerage. I can certainly manouver around the marina in reverse, it's just harder than forwards and…

Going backwards in the marina I often steer on the engine rather than the rudder (though I keep the rudder aligned with the engine of course). Obviously that's in a tiny sailing boat with an external engine, but I thought large ships also often have a steerable front propeller to assist with steering and mooring. Although maybe these very large ships use tugboats for that.

an outboard? that is very very different because you control the direction of thrust also.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#676

Post by deltarholamda »

paddy_m wrote: post #574
deltarholamda wrote: post #561

Earlier quoted context omitted.

This disconnect happens with boats quite a lot. For example, I can, by myself, pull a 45 foot grand banks trawler in shallow water. I know because I've done so. But at even very low speeds, I cannot stop it from hitting a pier. I have not tried to do this, but every harbor master has a bunch of stories about people trying to do so and getting a leg or an arm or something squished and pulverized. People who are not bo…

To anyone reading this who isn't an experienced boater: If you are invited onto someone else's boat, sit down and shut up during docking, don't talk to friends, let the captain concentrate. Don't help, if the captain wants you to do something, they will let you know. If you think you know better than the captain, and this advice is unknown to you, you don't know better. Being a good guest during docking shows experie…

Screwing around during docking is a great way to get to swim to shore at an unspecified later date.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#677

Post by LinuxBender »

lenerdenator wrote: post #453
paddy_m wrote: post #438

Youtube tracking analysis from a knowledgeable mariner. He says that at about 1:24 AM the ship loses power (from video feed) while traveling 8.5 knots. at 1:25.30 power is restored. at 12:25.59 the ship shows smoke. The ship has already drifted in the channel. It is believed that at this time the ship applied full reverse power as evidenced by the black smoke. (My analysis: the ship drifted but hasn't turned in the c…

How common are power outages on ships? I get that the captain might not have responded to it correctly but that seems like a thing that shouldn't happen, at least in my completely uneducated opinion.

Probably not the case here, but one possibility could be land-based remote hacking. [1]

[1] - https://warontherocks.com/2021/10/cant-sail-away-from-cyber-... (2021)

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#678

Post by bmitc »

dwightgunning wrote: post #24

DALI (IMO: 9697428) is a Container Ship and is sailing under the flag of Singapore. Her length overall (LOA) is 299.92 meters and her width is 48.2 meters [1]. Based on the track, it appears the ship changed course slightly and slowed as it approached the bridge [2]. [1] https://www.marinetraffic.com/en/ais/details/ships/shipid:28... [2] https://www.marinetraffic.com/en/ais/home/shipid:2810451/zoo...

Thanks for the link to the track. That's the first thing that I've seen that showed that I guess it's regular for these ships to pass under the center of this bridge. Is that correct?

If so, what I'm still not understanding is why ships are allowed to make that passage all on their own without any backup like a tugboat and why the bridge doesn't have secondary protection of its pillars. Because with a track like that and lack of either of those things, a catastrophic collision seems inevitable.

Does anyone know why the ship would make a sudden hard right during a sequence of power failures?

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#679

Post by bmitc »

jordanb wrote: post #464
lenerdenator wrote: post #453

Earlier quoted context omitted.

How common are power outages on ships? I get that the captain might not have responded to it correctly but that seems like a thing that shouldn't happen, at least in my completely uneducated opinion.

According to this book: https://www.amazon.com/Tankship-Tromedy-Impending-Disasters-... It is quite common and vessels often have outages that leave them Not Under Command. Usually they are safely at sea when this happens and they can drift for hours without causing problems. But of course there's always a possibility of it happening at exactly the wrong moment. The reasons for this are the usual: lack of redundancy,…

Thanks for the link to that book. I don't know if it's the because of this catastrophe, but it looks to be unobtanium at the moment. Will have to find it in the library.

> lack of redundancy

This is what I am surprised at from many angles. It seems to me that the ship, the port (in the form of lack of tugboats), and the bridge (in the form of lack of secondary protection of the pillars) all had a lack of redundancy and secondary options.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#680

Post by edward28 »

squigz wrote: post #650
koliber wrote: post #602

There was a video the other week on Reddit where a cargo ship devastated a few loading cranes in a port in Turkey. Now this. How often do cargo ships run into infrastructure? Is this just a coincidence that it happened twice in a few weeks?

What else do you think it might be?

Clearly one incompetent captain keeps getting reassigned across the world.
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