Francis Scott Key Bridge Collapse - Baltimore, MD

[Arthur Dent]

There are other bays in the states where it is customary to have tugs escort larger vessels past large bridges, even in standard shipping lanes. This will probably be made mandatory from here on out.

That's certainly an option, though apparently expensive. The bridge pier probably should also have had a better protection system installed at a larger perimeter around the pier, so the bumper takes the impact and dissipates it sufficiently to save the structure. I think newer bridges typically have such features. When they built this one is the 70s, there weren't ships anywhere near this big, so I guess it wasn't considered, though it certainly seems like a pre-emptive retrofit would have been wise and should be considered in similarly vulnerable locations.

[AWvsCBsteeeerike3]

@Arthur Dent

There's so much going on and so much unknown, it's impossible to really tell a lot of stuff.

But, yes the anchors are almost always at the front and I think there's a picture confirming this with the angle of the chain indicating it had been dropped/drug for some time with a lot of lead in the line. If the center of gravity is to the right side of the anchor, as would be the case if the anchor is dropped to the left, I'd think the back would swing to the right at least in relation to the anchor/front. Add in that the ship is already drifting to the right and it would be even more pronounced.

For massive ships like this, I think this one was 900+ feet long, there are going to be bow thrusters all over the place that produce a lot of thrust. Were they working? Were they used?

The camera angle is deceptive until the very end.

Regardless, the ship lost power about 3500' from the bridge. At 15 fps, that's about 4 minutes until impact but only ~3.5 ship lenghts.

There's a current that was apparently pushing the ship towards the pier and under the bridge as evidenced by the initial drift/marine traffic video. Would it have missed the bridge and just floated by had they done nothing? Not sure, but obviously it couldn't have had a worse impact than what happened. Though, I doubt many captains/pilots would just throw their hands up and say, well, fingers crossed for the next 4 minutes.

When going forward, turning left when done just with the rudder is the same principle as an airplane wing. Turn the wheel to the left to turn the rudder to the left to create the pressure difference at the rudder which causes the boat at the rudder (back) to swing to the right and the front, in turn, to swing to the left. Normally, you'd do that, then straighten the rudder and provide forward thrust in the new orientation following the bow which is pointed to the left of where it was prior to the turn. Given the proximity to the bridge, even if they had full power, I'm not sure they had enough room to do that (swing the back to the right then swing it back to the left to clear the pier).

Similarly, when going in reverse, the rotation changes when using the rudder alone. The back of the ship goes left and the front goes right. Which is why I think that rotation is from an aft thrust with the rudder to port because that's exactly what looks to happen. And, because it is exactly what would be needed to keep the propeller and rudder in the channel. Even going forward and turning to port may have caused the aft to swing into shallow waters if not hit the pier.

[Arthur Dent]

I think the camera angle is misleading in the sense that there is no depth perception, so it is impossible to understand where the boat is actually headed. From the beginning, it looks like it could be headed right at the pier, but the synced tracking data clearly shows it was headed right down the channel under the middle of the bridge until after they lose power. It immediately starts heading off course once power is restored. Though it is impossible to see the heading in the video, I think you can see the orientation of the boat just fine. As the boat turns right, it begins to point directly at the camera, and that rotation starts only/immediately when power is restored. If the issue were winds or current, it should have started with power loss not power restoration. The synced tracking tells the same story.

It's a good point about the thrusters. We don't know what caused the power failure, we don't know what exactly they tried to do, and we don't know what systems were functioning when power came back. I certainly have no familiarity with this stuff and don't intend to criticize the crew who had four minutes to react, diagnose, and try to correct. In aviation, you'd have a memorized power failure checklist. Don't know if there's anything similar here, or you just make it up on the fly.

Regarding the rudder in this situation, doesn't it mean they should have reversed their rudder position under reverse thrust? I don't know how the controls work, but maybe its confusing as they are still traveling forward but the direction of current flow at the rudder is reversed.

Edit: Thinking about this further, seems like it's just super difficult to get the maneuver you want under reverse thrust. To get your thrust vector pointed away from the pier, you'd have to point the bow at the pier. But I'm guessing the forward momentum and the forces on the keel are going to result in forces guiding the boat in the direction it is pointing.

[AWvsCBsteeeerike3]

That's a good question about the flow over (around, technically, I guess) the rudder and I'm not sure the answer. The rudder is right behind the prop, when moving forward, so the water being pushed (or pulled) by the propeller is going to be faster than what the speed of the boat through the water is (when going forward). And, in reverse, the rudder efficacy will degrade with increased forward velocity, I believe, because you're decreasing the velocity around the rudder by that amount. And, the rudder is in front of instead of behind the propeller.

If they would have reversed, and turned the wheel/rudder to the right, yes the back would have swung to the right and the bow would have swung to the left pointing them away from the bridge, but also putting the back of the boat near, if not out of, the channel. And, I don't know what they identified as the main problem. Nor do I know how confident they were in getting the mechanical equipment back.

In aviation, certainly, problems I believe are more universal. You're in the air and the main concern is the ground, particularly hitting it hard. And, you have aerodynamics which are not changed all that much by wind direction as well as the never changing forces of gravity to deal with. In channels, it's a bit different. The obstacles vary, the currents and winds have much more influence over the vessel, etc. But, yeah, you would think there would be a standard protocol of what to do.

[AWvsCBsteeeerike3]

When I start going ocd on stuff, it’s amazing how much tangential info comes to light.

For instance, I was watching this video hoping to learn about the physics and maneuvering that went into the last 4 minutes of the voyage that ended in a collision with a bridge.

I’d just assumed the ship insurers were going to be stuck with a massive payout likely reaching a billion if not multiple billions.

I never thought about the cause of loss of power aside from boat motors are notoriously unreliable…speaking from my own experience here. Even after watching this guy show the report of the vessel being in good shape did I think about it being anything other than motor failure, ship at fault, insurance pay out.

But within the first 5 minutes of the video I learn about refineries dumping [expletive] in diesel. Huh.

https://www.youtube.com/live/b-t5EZov7b ... DEeKf8rfi0

[AWvsCBsteeeerike3]

[Leroy]

I can answer any questions you may have because I seen Perfect Storm.

[AWvsCBsteeeerike3]

I can answer any questions you may have because I seen Perfect Storm.

How do it happen?

[Leroy]

The ice machine gives out and everything goes to hell.

[AWvsCBsteeeerike3]

The ice machine gives out and everything goes to hell.

Ahh, yes, but why did they have to return just because the ice machine broke, presumably they had plenty for a week or so and could have waited it out.