4 ms·

>the hydrodynamic effects of these large ships in relatively shallow and narrow canals is underappreciated I'm really surprised I haven't seen this mentioned.

>the hydrodynamic effects of these large ships in relatively shallow and narrow canals is underappreciated I'm really surprised I haven't seen this mentioned. A long time ago, I was trained as a merchant ship's navigation officer. One of the things we were taught (but unfortunately had few opportunities to practice), was using "bank cushion" or "bank suction" to use the hydraulic interaction between the hull and a narrow body of water like a river to navigate tight curves. These days, there are simulations that I'm sure capture these effects to it's easier to get some experience with them. Of course, in the case of the Ever Given it seems that the grounding was mainly due to not compensating for the strong cross winds.

EricE 6y ago
That and going ridiculously fast during a sandstorm. Juan Brown/Blancolirio channel has a good overview and he touches on hydronic interactions you reference too: https://m.youtube.com/watch?v=5iyn2q6s1Sk https://m.youtube.com/watch?v=5iyn2q6s1Sk
SPACE_LAWYER 6y ago
I learned about the bank effect from this article https://www.ft.com/content/171c92ec-0a44-4dc5-acab-81ee2620d3c1 https://www.ft.com/content/171c92ec-0a44-4dc5-acab-81ee2620d...
rswail 6y ago
> ... not compensating for the strong cross winds. Not compensating or not being able to compensate? One implies negligence, the other unavoidable.
- willyt 6y ago
  > Unavoidable Not really, weather forecasts are readily available and windage calculations are a thing.
  - ArnoVW 6y ago
    I believe the ft article says that they had 30 kts wind, and steered 'into the wind' to compensate. And since they were in a narrow canal, a sudden lull in the wind was enough. That doesn't contradict the 'going too fast' though. Just like we don't drive 55 mph in a residential neighborhood, thinking 'if a kid runs into the street that is not my fault, it was unforeseeable'.
    - Red_Leaves_Flyy 6y ago
      With a ship of this size couldn't they have the same problem if they go too slow?
      - op00to 6y ago
        Yes. The ship needs to have a certain amount of water going over the rudder to effect steering.
  - Jenk 6y ago
    Oh gosh why didn't the expert sailors whom all have many years of experience think about this trivial matter? Or could it be that navigating a 400mx60m, 220,000 tonne, 60m tall ship through a canal that is barely double the width with only 4m clearance is just a tad more difficult than that?
    - willyt 6y ago
      Well quite, that's why they might have waited for more favourable conditions instead of trying to take such a big ship through in force 7 'near gale' with poor visibility due to a sandstorm. Seems like a risky thing to do, no? Here's the risk assessment: Can you see where you are going? No. Is it harder to go in a straight line than normal? Yes. Is there anything nearby to hit? Yes. But the crew of the ship never do close quarters manoeuvring anyway it is the job of the local pilot to get the ship to near to the dock and tug crews who berth it. Maybe in the future the canal will change their risk assessment to hold ships this large when the weather conditions are unfavourable. Or maybe this is at the pilot's discretion already, but there was a 'human factors' issue as there is a post elsewhere suggesting that there might have been some friction with the pilot who was meant to be giving helm orders but was refusing to do so? Who knows?
kalium-xyz 6y ago
There is one thing I cannot find an answer for: Why did it draw a penis?
- shadowgovt 6y ago
  Boredom. Because of covid-19 and the fact that no particular nation is required by maritime law to take on shoreleave-seekers, crews have been at sea for between 2 to 3 times a standard rotation. You find your own way to make your fun. It is pretty funny though. I have to imagine the captain realizing his track had been discovered is every developer who ever put a comment like /* this is stupid but I'm doing it because my boss is also stupid */ somewhere in a million lines of code, thinking it would never come up in an audit.

EricE 6y ago

That and going ridiculously fast during a sandstorm. Juan Brown/Blancolirio channel has a good overview and he touches on hydronic interactions you reference too: https://m.youtube.com/watch?v=5iyn2q6s1Sk https://m.youtube.com/watch?v=5iyn2q6s1Sk

SPACE_LAWYER 6y ago

I learned about the bank effect from this article https://www.ft.com/content/171c92ec-0a44-4dc5-acab-81ee2620d3c1 https://www.ft.com/content/171c92ec-0a44-4dc5-acab-81ee2620d...

rswail 6y ago

> ... not compensating for the strong cross winds. Not compensating or not being able to compensate? One implies negligence, the other unavoidable.

willyt 6y ago
> Unavoidable Not really, weather forecasts are readily available and windage calculations are a thing.
- ArnoVW 6y ago
  I believe the ft article says that they had 30 kts wind, and steered 'into the wind' to compensate. And since they were in a narrow canal, a sudden lull in the wind was enough. That doesn't contradict the 'going too fast' though. Just like we don't drive 55 mph in a residential neighborhood, thinking 'if a kid runs into the street that is not my fault, it was unforeseeable'.
  - Red_Leaves_Flyy 6y ago
    With a ship of this size couldn't they have the same problem if they go too slow?
    - op00to 6y ago
      Yes. The ship needs to have a certain amount of water going over the rudder to effect steering.
- Jenk 6y ago
  Oh gosh why didn't the expert sailors whom all have many years of experience think about this trivial matter? Or could it be that navigating a 400mx60m, 220,000 tonne, 60m tall ship through a canal that is barely double the width with only 4m clearance is just a tad more difficult than that?
  - willyt 6y ago
    Well quite, that's why they might have waited for more favourable conditions instead of trying to take such a big ship through in force 7 'near gale' with poor visibility due to a sandstorm. Seems like a risky thing to do, no? Here's the risk assessment: Can you see where you are going? No. Is it harder to go in a straight line than normal? Yes. Is there anything nearby to hit? Yes. But the crew of the ship never do close quarters manoeuvring anyway it is the job of the local pilot to get the ship to near to the dock and tug crews who berth it. Maybe in the future the canal will change their risk assessment to hold ships this large when the weather conditions are unfavourable. Or maybe this is at the pilot's discretion already, but there was a 'human factors' issue as there is a post elsewhere suggesting that there might have been some friction with the pilot who was meant to be giving helm orders but was refusing to do so? Who knows?

kalium-xyz 6y ago

There is one thing I cannot find an answer for: Why did it draw a penis?

shadowgovt 6y ago
Boredom. Because of covid-19 and the fact that no particular nation is required by maritime law to take on shoreleave-seekers, crews have been at sea for between 2 to 3 times a standard rotation. You find your own way to make your fun. It is pretty funny though. I have to imagine the captain realizing his track had been discovered is every developer who ever put a comment like /* this is stupid but I'm doing it because my boss is also stupid */ somewhere in a million lines of code, thinking it would never come up in an audit.