3 ms·

> Do I have that right? With respect, I don't think that it is a case of that being wrong or right. The article posits that there is a lack of understanding ab

> Do I have that right? With respect, I don't think that it is a case of that being wrong or right. The article posits that there is a lack of understanding about hydrodynamics in shallow water. > ... hydrodynamics in shallow water are different. When a boat moves through the water, it pushes the water out of the way — it displaces it. “Where the water needs to be displaced, in a deep ocean it can go under the ship and that’s not a problem,” says Lataire. “But if it needs to go into shallow water, like the Suez, the water simply cannot go under and around.” > The Suez Canal is basically just a 24m-deep ditch dug in the ground to let the ocean in. When a ship comes by and displaces the water, the water has nowhere to go; it gets squeezed in between the ship’s hull and the floor and the sides of the ditch. A ship in a canal can squat, for example — it can dig its stern into the water. When water gets squeezed between a ship’s hull and a sand floor, it speeds up. As water flow speeds up, its pressure drops, pulling the hull down to fill the vacuum. The effect is more pronounced at the stern, and so the ship settles into a squat: bow up, stern down. > ... Lataire wrote his dissertation on a similar phenomenon as a ship passes close to a bank: the bank effect. The water speeds up, the pressure drops, the stern pulls into the bank and, particularly in shallow water, the bow gets pushed away. Stern one way, bow the other. A boat that had been steaming is suddenly spinning. > Most of the research and design on ship hulls goes into efficiency and stability at sea. But at sea is not where the Ever Given got stuck. And ships have gotten big, fast, which means the consequences of shallow-water hydrodynamics are changing by the year. Anyhow, the article argues gently that big ships are being built with scant regards for hydrodynamics in shallow waters, and it makes a case for some proper research before building more.

trhway 6y ago
>big ships are being built with scant regards for hydrodynamics in shallow waters, and it makes a case for some proper research before building more. doesn't seem so : https://en.wikipedia.org/wiki/Squat_effect https://en.wikipedia.org/wiki/Squat_effect "The third largest cruise ship in the world, MS Oasis of the Seas, used this effect to obtain an extra margin of clearance between the vessel and the Great Belt bridge, Denmark, 1 November 2009, on a voyage from the shipyard in Turku, Finland to Florida, USA.[5] The new cruise liner passed under the bridge at 20 knots (37 km/h) in the shallow channel, giving the ship extra clearance due to a 30 cm squat." The current situation with EverGiven seems to be more like a ship piloting error - as normally they are taught about the Bernoulli based bank/squat effects when piloting near ground or near other ships moving in parallel direction.
- banana_giraffe 6y ago
  Doesn't the Suez Canal have specialized pilots that take over going through the canal? If it pilot error, makes me wonder if it's more a case of not knowing something about the class of ship somehow.
  - CalChris 6y ago
    Yes and two were on board. https://gcaptain.com/ever-given-grounding-the-latest-from-the-ship-manager/ https://gcaptain.com/ever-given-grounding-the-latest-from-th...
    - Animats 6y ago
      “Arrangements are also being made for high-capacity pumps to reduce the water levels in the forward void space of the vessel and the bow thruster room.” Now it comes out that they're taking water. Things just got more complicated. At a minimum, it will be necessary to dig the bow out and do some patching. How big a deal this is remains to be seen. If they're lucky, it's just the connections for the bow thruster. If the hull has to be patched, it's a bigger job. Patching is quite possible, even for big holes. That's just a temporary fix. The ship may not be seaworthy for long trips. That monster ship will probably have to be towed to a nearby container port, probably Port Said, and the containers unloaded. Then probably across the Med to a dry dock that's big enough, probably one in Greece, for permanent repairs. But by then it will be out of the traffic lane and a concern only to the owners.
      - trhway 6y ago
        >Now it comes out that they're taking water. it is natural given that the ship did hit the protective boulders before getting onto the sand bank. I was wondering when it would come out.
      - elemeno 6y ago
        From another article on the FT it sounds like they’re talking about ballast, not that it’s taking on water. - “ Alongside specialists dredgers that are working to remove sand and soil from around the vessel, salvage experts Smit are looking to bring in high-powered pumping equipment to remove ballast water from the front and back of the ship, BSM said.”
IgorPartola 6y ago
No respect is due, I know nothing. I see what the article is saying, it’s point being about doing more research. It was really well written. I was just trying to see if I understood the theory of the events that happened that the article presented correctly, since there would be a much greater than 0 possibility that I missed some crucial step in reading it. As far as the larger point of the article/last paragraph, I couldn’t agree more. We keep taking up more space and using more resources while the plant stays the same size. It’s not sustainable. Maybe we need to stop shipping so much stuff around since let’s face it a decent amount of it is useless consumer junk. I can also see us building ships so large that they don’t go to ports but rather get unloaded onto smaller ships off shore, similar to how a planet to planet spacecraft might not be able to land/take off but only go between orbital stations.
- m4rtink 6y ago
  Actually transshipping at sea is petty hard - wave action will impact ships differently and could effectively grind them together, not only ruining your positioning to safely move cargo between ships but also might damage the ships themselves, especially if one of them is significantly bigger than the other. Nothing like this in a free fall environment, so this should be much easier to do in space. As long as there is no atmosphere and the shipscare not insanely big (too many km) or gravity gradient not insanely high (netron stars, etc.).
- fian 6y ago
  We already have ship to ship cargo transfers (Lightering): https://en.wikipedia.org/wiki/Lightering https://en.wikipedia.org/wiki/Lightering due to draft concerns for the larger vessel.

trhway 6y ago

>big ships are being built with scant regards for hydrodynamics in shallow waters, and it makes a case for some proper research before building more. doesn't seem so : https://en.wikipedia.org/wiki/Squat_effect https://en.wikipedia.org/wiki/Squat_effect "The third largest cruise ship in the world, MS Oasis of the Seas, used this effect to obtain an extra margin of clearance between the vessel and the Great Belt bridge, Denmark, 1 November 2009, on a voyage from the shipyard in Turku, Finland to Florida, USA.[5] The new cruise liner passed under the bridge at 20 knots (37 km/h) in the shallow channel, giving the ship extra clearance due to a 30 cm squat." The current situation with EverGiven seems to be more like a ship piloting error - as normally they are taught about the Bernoulli based bank/squat effects when piloting near ground or near other ships moving in parallel direction.

banana_giraffe 6y ago
Doesn't the Suez Canal have specialized pilots that take over going through the canal? If it pilot error, makes me wonder if it's more a case of not knowing something about the class of ship somehow.
- CalChris 6y ago
  Yes and two were on board. https://gcaptain.com/ever-given-grounding-the-latest-from-the-ship-manager/ https://gcaptain.com/ever-given-grounding-the-latest-from-th...
  - Animats 6y ago
    “Arrangements are also being made for high-capacity pumps to reduce the water levels in the forward void space of the vessel and the bow thruster room.” Now it comes out that they're taking water. Things just got more complicated. At a minimum, it will be necessary to dig the bow out and do some patching. How big a deal this is remains to be seen. If they're lucky, it's just the connections for the bow thruster. If the hull has to be patched, it's a bigger job. Patching is quite possible, even for big holes. That's just a temporary fix. The ship may not be seaworthy for long trips. That monster ship will probably have to be towed to a nearby container port, probably Port Said, and the containers unloaded. Then probably across the Med to a dry dock that's big enough, probably one in Greece, for permanent repairs. But by then it will be out of the traffic lane and a concern only to the owners.
    - trhway 6y ago
      >Now it comes out that they're taking water. it is natural given that the ship did hit the protective boulders before getting onto the sand bank. I was wondering when it would come out.
    - elemeno 6y ago
      From another article on the FT it sounds like they’re talking about ballast, not that it’s taking on water. - “ Alongside specialists dredgers that are working to remove sand and soil from around the vessel, salvage experts Smit are looking to bring in high-powered pumping equipment to remove ballast water from the front and back of the ship, BSM said.”

IgorPartola 6y ago

No respect is due, I know nothing. I see what the article is saying, it’s point being about doing more research. It was really well written. I was just trying to see if I understood the theory of the events that happened that the article presented correctly, since there would be a much greater than 0 possibility that I missed some crucial step in reading it. As far as the larger point of the article/last paragraph, I couldn’t agree more. We keep taking up more space and using more resources while the plant stays the same size. It’s not sustainable. Maybe we need to stop shipping so much stuff around since let’s face it a decent amount of it is useless consumer junk. I can also see us building ships so large that they don’t go to ports but rather get unloaded onto smaller ships off shore, similar to how a planet to planet spacecraft might not be able to land/take off but only go between orbital stations.

m4rtink 6y ago
Actually transshipping at sea is petty hard - wave action will impact ships differently and could effectively grind them together, not only ruining your positioning to safely move cargo between ships but also might damage the ships themselves, especially if one of them is significantly bigger than the other. Nothing like this in a free fall environment, so this should be much easier to do in space. As long as there is no atmosphere and the shipscare not insanely big (too many km) or gravity gradient not insanely high (netron stars, etc.).
fian 6y ago
We already have ship to ship cargo transfers (Lightering): https://en.wikipedia.org/wiki/Lightering https://en.wikipedia.org/wiki/Lightering due to draft concerns for the larger vessel.