What 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.
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.
If 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.
Because there are a lot of bots out there. Some are neutral scrapers just contributing to website load, while some are actively malicious. CAPTCHA's were a crucial development that allow the internet to continue to function efficiently and openly (for humans) as internet access expands in regions where there are no repercussions for cybercrime.
"Please don't complain about website formatting, back-button breakage, and similar annoyances. They're too common to be interesting. Exception: when the author is present. Then friendly feedback might be helpful."
if 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.
Relatedly, 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.
The 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.
If 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.
The 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?
Subscriptions 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.
You're already paying more for this on a per-household basis through advertising, for lower-quality content (and killing off quality), with no say on the endpoint publisher revenue, through ad-supported media.
Households with higher income would pay more. Households with low income would have access to all the world's published knowledge.
Tiered remuneration based on a judged quality metric is one possible approach to this.
Another approach would be to open a specified number of journalist / creator slots and fund those to a living level (perhaps in addition to the consumption metric). As with many other complex work-products, very short-cycle quality metrics tend to be little better than noise. I believe Cathy O'Neill's written or spoken on this.
Clickbait would result in a low revenue tier.
I've fleshed this out in more detail, my proposal is substantially the same as others have proposed, including Phil Hunt (Pirate Party UK) and RMS, whom you may have heard something of recently, as well as mentions-in-passing by Joseph Stiglitz and others.
Media, Advertising, Sustainability, Externalities, and Impacts: A light reading list dredmorbius↗
Thinking some more on this ...
... the notion of a market in which quality tiers are served based on bids based on perceived benefit and costs of provisioning might be one approach. Details naturally remain to be worked out.
But in the "clickbait" tier, if a GPT-3 ML/AI would be sufficient to supply a steady stream of memes, with sufficiently low negative social externalities, the profit motive for entering into the niche would remain quite low.
In-depth investigative journalism would be bid within a distinct an separate marketplace, sufficient to cover costs of production and maintenance.
In broadcast, SLAs can be achieved based on the portion of both spectrum (bandwidth) and time (a day still has only 24 hours, plus or minus the odd leap/skip second(s)), such that targets of specific levels of service could be required.
In print it's column-inches that are determinate, as well as circulation.
Online media shares some attributes of both, with measurements possible in both personal media time budgets (time/day or time/month spent on given sites or types of media), and in terms of article counts, word counts, above-the-fold visibility, SERP rankings, and ultimately of what Facebook apparently calls "prevalence" (items * views or presentations within the stream).
What's "current"? Journalism is a much worse business than it was 10 years ago and everyone working in it is less qualified as a result, so I think we need to be raising their revenue.
Micro transactions is a model that might be a good alternative to all of those. The idea is that if you agree on paying say 1 dollar you get to access that specific article. There can of course be variations like you pay x to get future access to y number of articles.
So 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.
If we insist on not paying for journalism then what little quality journalism we have left will die. Vote with your wallet if you want a future that isn’t just listicles and manufactured outrage.
Alternatively if more people paid for valuable services by skilled professionals that cost a lot to provide, the service would be better funded and/or could be cheaper for everyone.
I 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
In 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.
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.
"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.
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.
“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.
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.”
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.
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.).
Watching this timelapse of the canal transit it you can see all the forces and corrections that happen, and coupled with the lenght, mass and momentum, I'm surprised they don't have more of these events.
That is the theory that matches the data sent by the transponder and is the opinion of an expert hydrodynamicist. So pretty much yeah, that is how it worked.
One suspects the only thing that would have prevented this disaster is if they pilot had put it into full reverse when the wind stopped pushing it. There is so much momentum on these things it would continue to go forward, but it would have a force vector in reverse that was applying (perhaps successfully, perhaps not) a counter torque to the direction of travel.
Ships in reverse behave in ways that are non-intuitive (https://en.wikipedia.org/wiki/Propeller_walk). Depending on the direction of the prop walk it could compound the problem.
Another artifact of traditional (non-azimuth) propeller driven ships in reverse is that they have very little steering control if they are moving slowly as steering requires water moving over the rudder. In forward water is actively being pushed over the rudder due to its position behind the prop, but in reverse this flow is not as strong.
I don't disagree, the paper talks about torques as opposed to steerage.
That said, apparently this particular ship has a couple of 60MWatt bow thrusters so presumably one would use that given it has an even better lever arm with respect to the CG than the props do.
All in all, canal pilot is a highly skilled job, and I'm surprised the two pilots on this ship had this sort of accident.
Given the enormous costs of blocking the canal I'm surprised it's not almost entirely automated similar to autopilots. Simulating the hydrodynamic and forces from local weather seem tractable to do in real-time with a few higher end Nvidias. At least to a high enough grid resolution that'd exceed pilot intuition and training.
If the forces (wind, effects of the shallow canal, sides of the canal) cannot be neutralized, then I can only imagine slowing down the craft itself to at buy more time to keep to the center of the canal....
But I couldn't help but thinking about the future effects of global warming, specifically gusting winds, and wondering if we're going to see this kind of jamming of the Suez more and more frequently.
> slowing down the craft
Unfortunately, the ship's ability to steer left/right primarily comes from the fact that it is moving forward, and the rudder is deflecting the moving water in a certain direction. Come to a complete halt, and the winds will get the best of you anyway.
I'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.
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.
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.
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.
Pressure in fluids is a funny thing. Put your thumb at the open end of a hose with water flowing through it: you'll feel high pressure. But along the sides of the hose the pressure from the flowing water will be a lot lower, and if you poke a hole into the side while leaving the open end open, then you might even observe that hole sucking air in!
Good 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!
There’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
Links 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?
Notice 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.
I 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.
>> 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.
100 comments
[ 3.3 ms ] story [ 159 ms ] threadFavourite 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.
https://en.m.wikipedia.org/wiki/MONIAC
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.
Even in the 1980s the Fed under Paul Volcker tried to reign in inflation too quickly, causing a recession.
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.
http://investorsnewsblog.com/2021/03/25/the-bank-effect-and-...
> 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?
https://news.ycombinator.com/newsguidelines.html
https://www.youtube.com/watch?v=_dbahpPeoJQ
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://www.crescentpilots.com/
That's about what the current publishing sector take is now.
You're already paying more for this on a per-household basis through advertising, for lower-quality content (and killing off quality), with no say on the endpoint publisher revenue, through ad-supported media.
Households with higher income would pay more. Households with low income would have access to all the world's published knowledge.
That seems like an exceedingly equitable trade.
Another approach would be to open a specified number of journalist / creator slots and fund those to a living level (perhaps in addition to the consumption metric). As with many other complex work-products, very short-cycle quality metrics tend to be little better than noise. I believe Cathy O'Neill's written or spoken on this.
Clickbait would result in a low revenue tier.
I've fleshed this out in more detail, my proposal is substantially the same as others have proposed, including Phil Hunt (Pirate Party UK) and RMS, whom you may have heard something of recently, as well as mentions-in-passing by Joseph Stiglitz and others.
In rough order of significance:
A Modest Proposal: Universal Online Media Payment Syndication https://old.reddit.com/r/dredmorbius/comments/1uotb3/a_modes...
Why Information Goods and Markets are a Poor Match https://old.reddit.com/r/dredmorbius/comments/2vm2da/why_inf...
Repudiation as the micropayments killer feature (Not) https://old.reddit.com/r/dredmorbius/comments/4r683b/repudia...
Specifying a Universal Online Media Payment Syndication System https://old.reddit.com/r/dredmorbius/comments/2h0h81/specify...
The Medium Is the Message: how the technological and revenue environments shape content https://old.reddit.com/r/dredmorbius/comments/278e2o/the_med...
Content Syndication: Phil Hunt's Broadband Tax / Content Compensation Fund proposal, and the Rent-Seeking Economy https://old.reddit.com/r/dredmorbius/comments/1vknhc/content...
Richard Stallman's "Internet Sharing" content syndication proposal (2012) https://old.reddit.com/r/dredmorbius/comments/3p0bp6/richard...
What the academic publishing industry calls "theft" the world calls "research": Why Sci-Hub is so popular https://old.reddit.com/r/dredmorbius/comments/4p2rwk/what_th... (References Stiglitz.)
Forbes asks: Why do programmers hate advertising so much? https://old.reddit.com/r/dredmorbius/comments/24107v/forbes_...
Media, Advertising, Sustainability, Externalities, and Impacts: A light reading list dredmorbius ↗ Thinking some more on this ...
... the notion of a market in which quality tiers are served based on bids based on perceived benefit and costs of provisioning might be one approach. Details naturally remain to be worked out.
But in the "clickbait" tier, if a GPT-3 ML/AI would be sufficient to supply a steady stream of memes, with sufficiently low negative social externalities, the profit motive for entering into the niche would remain quite low.
In-depth investigative journalism would be bid within a distinct an separate marketplace, sufficient to cover costs of production and maintenance.
In broadcast, SLAs can be achieved based on the portion of both spectrum (bandwidth) and time (a day still has only 24 hours, plus or minus the odd leap/skip second(s)), such that targets of specific levels of service could be required.
In print it's column-inches that are determinate, as well as circulation.
Online media shares some attributes of both, with measurements possible in both personal media time budgets (time/day or time/month spent on given sites or types of media), and in terms of article counts, word counts, above-the-fold visibility, SERP rankings, and ultimately of what Facebook apparently calls "prevalence" (items * views or presentations within the stream).
https://nitter.cc/guyro/status/1337493574246535168
https://toot.cat/@dredmorbius/105372688403486098
Also FT is not a US business.
And no, to pre-empt it the mythical "micropayments" solution isn't going to replace either.
Economist: $189, FT: $372
You mean $365.25, as there are 365.25 days in a year. ;)
I definitely wouldn't use them as my environment reporting source, but for politics and business they're hard to beat.
The closer you are to the action the more skin in the game you have and the better intel you need.
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.
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.
doesn't seem so :
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.
https://gcaptain.com/ever-given-grounding-the-latest-from-th...
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.
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.
“ 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.”
"Approaching the bridge at 23 knots (43 km/h; 26 mph), the ship passed under it with less than 60 centimetres (2 ft) of clearance."
EDIT: found a video https://www.youtube.com/watch?v=RYf8F9-jULo
Mind. Blown.
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.
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.).
https://en.wikipedia.org/wiki/Lightering
due to draft concerns for the larger vessel.
https://youtu.be/L0J-VIvKLsc
(I wanted to credit the person who posted it yesterday, but can't find him/her)
edit: better one https://youtu.be/oWF7A9Ujr3w
One suspects the only thing that would have prevented this disaster is if they pilot had put it into full reverse when the wind stopped pushing it. There is so much momentum on these things it would continue to go forward, but it would have a force vector in reverse that was applying (perhaps successfully, perhaps not) a counter torque to the direction of travel.
Another artifact of traditional (non-azimuth) propeller driven ships in reverse is that they have very little steering control if they are moving slowly as steering requires water moving over the rudder. In forward water is actively being pushed over the rudder due to its position behind the prop, but in reverse this flow is not as strong.
That said, apparently this particular ship has a couple of 60MWatt bow thrusters so presumably one would use that given it has an even better lever arm with respect to the CG than the props do.
All in all, canal pilot is a highly skilled job, and I'm surprised the two pilots on this ship had this sort of accident.
But I couldn't help but thinking about the future effects of global warming, specifically gusting winds, and wondering if we're going to see this kind of jamming of the Suez more and more frequently.
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.
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.
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.
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!
Do most HN users have one or more accounts to sites like this?