10 ms·
The bank effect and the big boat blocking the Suez
- samizdis 6y agoWhat a terrific article, certainly the only one I've seen to look at the science of this - and to point out that the ship didn't just hit sand: that section of the canal is lined - it went through "protective" boulders to reach that sand. Favourite quote: Sailors talk about hydrodynamics the way CEOs talk about macroeconomics: they either treat it with mystical reverence, or they claim to understand it and are wrong. Unlike with macroeconomics, though, if you know what you’re doing you can test the propositions of hydrodynamics on actual, physical models in a lab. As in: you build little boats and then you drag them through the water, in a towing tank. Hydrodynamics is what a five-year old would do, if a five-year old had a PhD.
- p10jkle 6y agoOf course, you can test macroeconomics with a water tank too https://en.m.wikipedia.org/wiki/MONIAC https://en.m.wikipedia.org/wiki/MONIAC
- lupire 6y agoBut hydrodynamics experiments actual give correct answers, because physics empirically matches physical theory, but economics doesn't.
- astrange 6y agoThere's empirical economics now. https://www.nobelprize.org/prizes/economic-sciences/2019/summary/ https://www.nobelprize.org/prizes/economic-sciences/2019/sum... I mean, the macro men are still out there, their predictions are still always wrong, and they still refuse to admit it. But at least we're starting to not listen to them.
- sceadu 6y agoSee also: https://wiki.lspace.org/mediawiki/Glooper https://wiki.lspace.org/mediawiki/Glooper
- nroets 6y agoThat model predates important advances like Rational Expectations. Even in the 1980s the Fed under Paul Volcker tried to reign in inflation too quickly, causing a recession.
- neilwilson 6y agoIf you believe modelling that actors can see the future perfectly is an advance - which is what Rational Expectations requires. It's a fudge to try and explain why monetary policy works instantly rather than in eighteen months to two years time. However the evidence of the failure to raise inflation to 2% demonstrates that it is wrong in practice. Unsurprisingly the real world can't see the future perfectly. Which is why you need advanced automatic stabiliser systems that actually work on the real world, not just the imagination.
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- neonate 6y agohttps://archive.is/pmUEm https://archive.is/pmUEm
- burlesona 6y agoIt is infuriating that archive captchas are positioned offscreen on mobile and therefore can’t be solved.
- samizdis 6y agoYou might try this link, which I got via a DDG search and which seems to be the complete article: http://investorsnewsblog.com/2021/03/25/the-bank-effect-and-the-big-boat-blocking-the-suez/ http://investorsnewsblog.com/2021/03/25/the-bank-effect-and-...
- cwwc 6y agoIf ya go portrait mode on Safari you can access
- kristianp 6y agoInteresting, I've never seen a captcha on archive.is. I'm on Android on wifi.
- deleted 6y ago[deleted]
- jp57 6y agoIt is infuriating to have to solve a captcha just to see a page. > Why do I have to complete a CAPTCHA? Completing the CAPTCHA proves you are a human and gives you temporary access to the web property. No kidding. But why?
- sn_master 6y agoTo avoid DDoS and content scrapers that would harvest the article text and put it on link farms to get clicks from confused search engines.
- dnautics 6y agoif you ever have the chance to visit new orleans, there is a turn in the river near the public boardwalk and it is simply amazing to watch giant ships (though not nearly as big as the evergreens) take a drifting bank through that turn at what looks like 15 kts, maybe more.
- TheSpiceIsLife 6y agoI think this video shows the turn you're talking about? https://www.youtube.com/watch?v=_dbahpPeoJQ https://www.youtube.com/watch?v=_dbahpPeoJQ
- rainbowzootsuit 6y agoRelatedly, the Mississippi River has pilots associations who are responsible to navigate vessels through the river. The Mississippi probably a more complex environment than the Suez Canal given the significant number of turns and strong currents but I'm somewhat surprised there isn't something similar there in Egypt as it seems like a narrow passage. https://en.m.wikipedia.org/wiki/Mississippi_River_Pilot https://en.m.wikipedia.org/wiki/Mississippi_River_Pilot https://www.crescentpilots.com/ https://www.crescentpilots.com/
- yuliyp 6y agoThe Suez Canal, like many ports and other canals, requires a Pilot to board every vessel that transits it. The pilots are local experts working with the Suez Canal Authority that work with the ship captains onboard the ship to help them navigate the canal.
- more_corn 6y agoIf you keep posting paywalled articles paywalls will persist. If you ignore them all they will cease to be relevant and they will die. Vote with your attention for the future you want.
- dageshi 6y agoSo you're saying we should avoid paywalled content, irrespective of how good it is and encourage ad supported content instead because those are the only two real alternatives. And no, to pre-empt it the mythical "micropayments" solution isn't going to replace either.
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- jefft255 6y agoThe future I want includes competent journalists being paid and websites that aren’t filled by garbage ads and nagging. Not saying paywalls are nice, but what is the future you want?
- dredmorbius 6y agoSubscriptions rolled into broadband/mobile at $120/yr US net, tiered by local prevailing wealth, and pro-rated based on estimated access seems a good start. That's about what the current publishing sector take is now.
- colinmhayes 6y agoI prefer to pay for the services I actually use, not let someone else choose for me.
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- rossdavidh 6y agoMy goodness, that was odd. I just read a news article, and yet I feel better informed about something.
- disgruntledphd2 6y agoThe FT is expensive, but well worth it (it's good because it's expensive, as journalism is).
- andrepd 6y agoThey have their own biases, but at least they're very good when read in combination with other sources.
- disgruntledphd2 6y agoYeah, totally. But at least you can rely on them to mostly avoid clickbait, and actually have people on the ground to do the reporting. I definitely wouldn't use them as my environment reporting source, but for politics and business they're hard to beat.
- eternalban 6y agoMy theory of newspapers: accuracy increases in direct relationship to color of paper and proximity of readership to serious money.
- ReptileMan 6y agoThere is the reason why Taleb in his brilliant piece Intellectual yet idiot chose to rip the New Yorker reading crowd and not FT. The closer you are to the action the more skin in the game you have and the better intel you need.
- dgritsko 6y agoI learned the term "riprap" from this article. I've seen plenty of examples in person, I just never knew it had a specific name. https://en.wikipedia.org/wiki/Riprap https://en.wikipedia.org/wiki/Riprap
- IgorPartola 6y agoIn other words it was going north, wind was blowing from the West. To correct, the ship was steering a bit to the left to compensate and have the whole ship go forward. Then suddenly the wind stopped, the bow got too close to the left/West bank, and the bank effect repelled it swinging it to the right. Once the bow got stuck, the stern got stuck on the left as it kept going forward and the ship spun clockwise. Do I have that right? Also I have seen pictures of the bow but none of the stern. What’s the situation there? It sounds like the riprap might need to be cleared out on both ends before the ship can be moved out of the way.
- samizdis 6y ago> 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.
- caseysoftware 6y agoI've taught a ton of people to fly RC helicopters and drones and the physics of it is the hardest part. The lack of friction throws off our sense of control. I tell people to steer sooner and more slowly than they think they should because "swerving" to miss something isn't really a thing. You just crash. And flying behind/below things is easier. The second you get up above the tree line or from behind that building where there's real wind, it's 10x harder.
- ummonk 6y agoWhen 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. Yet another article that needlessly complicated things by invoking the Bernoulli principle. It’s a lot simpler to explain: the space behind the stern needs to suck water into it so the stern area is at lower pressure, while the space around the bow needs to push water out of the way so it’s at higher pressure. The closer you are to the sea floor or bank, the bigger the effect since there isn’t much space to push water away and pull water from.
- JxLS-cpgbe0 6y agoYour explanation is longer and harder to understand. (How do you "invoke" Bernoulli's principle?)
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- simonh 6y agoWhy do they need to be at higher or lower pressure? That doesn't explain anything.
- bopbeepboop 6y agoThe ship is moving. The bow moves water out of the way when it moves forward and the stern vacates space which the water fills. So water is going away from the bow (positive pressure) but towards the stern (negative pressure). When a ship travels, water moves from the front to the back — and this shifting the water creates pressure as the water moves (which is also where drag comes from). If the water only has a narrow space to move, it has to move faster through that area, so the pressure is higher/lower. (Higher before where it bunches up on the bow, lower after where it rushes to fill behind the stern.) If one side has more space than the other (eg, left has less space) the the water goes faster on that side and so the pressures on that side are more extreme (eg, pushing the left bow rightward and sucking the left stern leftward — turning the ship right). That is, the normal front-to-back pressure can cause a twisting force if the flow isn’t balanced left-to-right. Because the side with less flow ends up with water bunching up at the front and not enough in the back.
- j3th9n 6y agoPossible solution?: blow air through pipes in the ground to make the sand fluid.
- laurent92 6y agoGood point. I guess they’d have to dredge the canal afterwards. I’m curious what the solution will be, but I’m most disappointed about the lack of photos, videos, reports about what is broken (it’s taking in water ; did it have an electrical breakdown? why did it draw a d... before entering the canal? pilot immaturity?). I guess it’s a side-effect of being ashore far away from population. We’re pretty much left with 2 images of a digger, a satellite, and no public communication from the Smit Savage company (who’s in charge of the multimillion salvage). Not all the world is covered with handheld reporters, finally!
- notfromhere 6y agoThere’s a village right by it. The Egyptian govt is telling locals not to take pictures; Suez brings in a lot of revenue for the govt, so they won’t want to dissuade people from not planning their route through there
- myrandomcomment 6y agoLinks like this bring up a question. FT is paywall. It would be interest to understand what percent of HN users have subscriptions to sites like the WSJ, WaPo, FT, etc. I have an ft.com subscription so I could read this (well written on complex topic). For most WSJ or the like unless it is something I would find really interesting, I just go oh well and skip. Do most HN users have one or more accounts to sites like this?
- riffraff 6y agoNotice that for FT you can generally google the title, and then when you click the link FT will let you read the content, as part of some logic that you have to let people read the search results if you want good SEO.
- Clewza313 6y agohttps://archive.is/rHatw https://archive.is/rHatw
- pvaldes 6y agoI wonder why they weren't moving yet a different smaller ships from the Mediterranean to the other side of the canal to receive the blocked ship cargo first, and maybe also part of the cargo of the other ships later. That would gave more time to rescuers and improve the situation for everybody, one box at a time.
- thunderbong 6y ago>> Wind definitely played a role, but there was probably something else happening, too. The ships keep getting bigger. But everything on Earth stays the same size.