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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

#821

Post by [deleted] »

bastardoperator wrote: post #494
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…

The video is surreal, it looks like it barely bumps the bridge and 2 seconds later the entire thing is gone. I don't know what I was expecting, the bridge just looked extremely fragile, makes me wonder what other bridges are at risk of an event like this.

[deleted]

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

#822

Post by reactordev »

twic wrote: post #801
reactordev wrote: post #749

Earlier quoted context omitted.

At this point in the journey, they were cleared of the docks but not the channel. There wouldn't be a docking pilot on board nor would there be any tugs. It was cleared and under it's own propulsion until it wasn't. My sailors guess from the footage and the reports is diesel generator failure(s) resulting in loss of power, restoration of power, then loss of power again. Bypassing the diesel generator (which provides…

The ship's managers (which I believe means the company which chartered it from its owners, and were operating it) say there were two pilots on board: https://www.synergymarinegroup.com/dali-imo-9697428/

Well then there were two pilots aboard to see it into the Chesapeake…

Still, a diesel gen malfunction would render them useless unless one of them was a diesel mechanic as well (we sailors often have multiple credentials).

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

#823

Post by rightbyte »

OJFord wrote: post #780
DiggyJohnson wrote: post #703

Earlier quoted context omitted.

Because horn blasts are very specifically meant to communicate something to other ships. Once you're in "just blast it" mode you're seconds from disaster. I recognize the nobility of your suggestion, but I don't think it could have saved more than couple lives at most, probably none.

Well yeah, they were only minutes away at the point they lost power, there was very little time to do anything at all, that's why I asked. Personally I can't really imagine anyone holding it against them for using the 'signal that's for other ships' 'incorrectly' or 'against protocol' in such a situation. I think the comments speculating that the horn is either purely or in some way (e.g. solenoid) dependent on elect…

There is a proper signal. You are supposed to give at least five short signals if you think there is an impeding collision.

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

#824

Post by dgfitz »

depereo wrote: post #794
chx wrote: post #766

Earlier quoted context omitted.

> It's my intention that the federal government will pay for the entire cost of reconstructing that bridge and I expect the Congress to support my effort This is what he said. I would expect Congress to play along too -- just how unpopular would it be to abandon Baltimore??

Republican side probably doesn't care; Maryland voted 65% for a democratic party president.

Baltimore city and PG county voted for a democratic president. Rest of the state was red.

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

#825

Post by jethro_tell »

esaym wrote: post #673
jcgrillo wrote: post #555

Earlier quoted context omitted.

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 start…

This is actually common for a 2 stroke type engine and used in things like gas golf carts and snow machines. The direction the engine is started is the direction it runs.

So to accomplish this for propulsion, you'd add a reverse polarity switch for your starter and you're good to go.

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

#826

Post by hinkley »

millzlane wrote: post #158
jxdxbx wrote: post #136

Not that it matters to anyone else, but having driven across that bridge dozens of times with my kids, this is just shocking. It’s one of the main corridors in the area. Thank god it happened in the middle of the night, though that’ll be no consolation to the families of those who may have died.

Local to the area. This was devastating news to wake up to. I don't know what's wrong with me but seeing this and knowing there were casualties made me cry. Edit: Maybe I'm just tired and need more sleep.

Do you happen to know how they stopped traffic? Are there warning lights at the ends of the bridge? I have seen bridges of this sort but they are fairly rare.

I'm wondering if that's how they stopped almost all of the traffic. Flip a switch, most people stop, a couple of assholes blow through the caution and FAFO.

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

#827

Post by HPsquared »

efitz wrote: post #767
jameshart wrote: post #748

Earlier quoted context omitted.

Isn’t there a pretty big difference in how much rudder authority you get between just making way astern, and having the engine in full reverse while still traveling forwards at seven knots?

It's complicated. The rudder is a wing, it's just vertically oriented and underwater. The rudder is capable of stalling, just like any wing. The rudder only produces lift related to the flow of water over the rudder. The lift produced by the rudder is what is experienced as turning force. The tiller or wheel changes the angle of attack. I used to helm a racing sailboat with a high aspect (long & narrow) rudder. It co…

I wonder if the "prop walk" effect might be stronger in shallow water.

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

#828

Post by dathinab »

JohnBooty wrote: post #245
dathinab wrote: post #202

Earlier quoted context omitted.

At least in the links with the video now you can see that the container ship directly hits one of the two main (and in the central area only) pillars completely collapsing it. No matter(1) the engineering there is no pretty much way to not lose the whole large middle area and left area leading to the destroyed pillar in that situation. Such a collapse crates so much force (tension vibrations etc.) so that the collaps…

It certainly does not seem reasonable to design a bridge pillar to withstand a direct impact from a massive cargo ship. But I guess I thought that maybe there was... typically some kind of earthen buffer around the pillar to prevent such an impact? That's probably impractical too, I guess. I guess I just didn't realize ~$1bn bridges were one fluky ship accident away from total collapse at any given time. I think mayb…

In smaller channels and similar it's not that uncommon to have crash barriers. For example in many Berlin channels and rivers.

And while I'm not quite sure what it is for the bridge had concrete pillars orthogonal in front of the pillars (this picture shows them well, to be clear I do NOT mean the power line isles: https://www.upi.com/News_Photos/view/upi/7191ba50f17c5a68307...). They would have stopped the ship if it would have went orthogonal to the bridge (i.e. if they mistook where the pillar where in a otherwise normal situation). Through not sure if that was the purpose of them.

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

#829

Post by dathinab »

Reason077 wrote: post #279
JohnBooty wrote: post #245

Earlier quoted context omitted.

It certainly does not seem reasonable to design a bridge pillar to withstand a direct impact from a massive cargo ship. But I guess I thought that maybe there was... typically some kind of earthen buffer around the pillar to prevent such an impact? That's probably impractical too, I guess. I guess I just didn't realize ~$1bn bridges were one fluky ship accident away from total collapse at any given time. I think mayb…

When Florida's Sunshine Skyway bridge was partly collapsed by a similar incident in 1980, the replacement bridge was built with a series of "structural dolphins" and concrete barriers to protect against ship strikes. You can see them in the image linked below: https://en.wikipedia.org/wiki/Sunshine_Skyway_Bridge#/media/...

interestingly the bridge has such dolphins

but only on per-pillar per-direction and with quite a bit of distance between it and the pillar

one some pictures you can see that the ship barley missed one of them due to the angle it was going at

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

#830

Post by inferiorhuman »

CydeWeys wrote: post #598
thekid314 wrote: post #597

Earlier quoted context omitted.

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.

All pilots are "harbor pilots". Crew members who control the ship outside of port are just called crew members (captain, first mate, 2nd Officer, that kind of thing), never pilot.

  All pilots are "harbor pilots".
In California, at least, that's not strictly true. They get paid quite handsomely ($400–500k as of a decade ago) to avoid hitting stuff in specific waterways around the Bay Area.

https://sfbarpilots.com

One had a nasty pill habit and crashed an oil tanker under his purview into the Bay Bridge.

https://www.justice.gov/opa/pr/guilty-plea-case-cosco-busan-...

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