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Comment by outside1234 | Hacker News Reader

I'm amazed the ships behind can stop in time and that there wasn't a horrible multi tanker/container ship accident. My understanding is that the momentum these large vessels have mean that it can take 3 or more km for them to stop.

ref: https://www.sciencedirect.com/topics/earth-and-planetary-sci....

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This guy talks about it

https://www.youtube.com/watch?v=7hoPmPhwLq4

apparently it was a problem as they were going ~13 knots as it was at the beginning of the canal. The first one Maersk Denver did ok slowing down gradually but the second one Asia Ruby almost crashed into it or ran aground as well

It would be much shorter in these circumstances. Your link is talking about 400,000 ton tanker ships. Container ships like the Ever Given are closer to 200,000 tons. And the cruising speed of a container ship is around 24kts, though I think they run slower than that nowadays to conserve fuel. The speed limit in the Suez Canal is nominally 8kts, but the Ever Glued was reportedly going 13kts when it ran aground. I would guess that that isn't unusual. With half the speed and half the mass, the stopping distance would probably be more like half a kilometer.

I'm going to assume that "Ever Glued" is not a mistake, but a happy little autocorrect accident.

The stopping distance is known, so presumably the pilots space the ships deliberately so that they can stop safely.

didn't the ship lose power before running aground? If so that means the ship would still be coasting and there would be time to warn the ship behind to stop. It'd be much worse if the ship was intentionally steered into the canal banks.

There was some early speculation that they might have lost power, but according to most reports they did not.

How do they warn folks behind? Lamps? Radio? aIS?

I'm not sure if they strictly need to be warned. Every ship of such size runs lots of radars already. They probably noticed the ship slowing down already, and adjusted their own speed.

Marine VHF radio. Ships are supposed to maintain a listening watch on Channel 16. Modern radios also have DSC capability to automatically alert when another ship signals distress, even if they’re working a different frequency.

And yes, a large ship would also be monitoring AIS and have onboard radar.

Yes, even my 18ft Zodiac has these features on the VHF. A container ship definitely has redundant radios with battery backup.

In the absolute worst case, they would fall back to flaghoists, blinkers and semaphore.

Probably radio, they all have pilots on board who radio each other and the harbor.

Radio running on backup power?

Handheld radio would work as a backup.

Fixed wing pilot here. Handheld radio checklist item before I head out for flight. Even though my plane has redundant comms. Comms don’t work in a failed power scenario!

I would think a call or text would do the trick.

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