12 ms·

Was There a Problem with the Rio Pool?

229 points by furyg3 10y ago

Vexs 10y ago
That seems pretty damning to me personally, but I'm not a statistician. It's also something I would never think could give an advantage, but I guess it makes sense that it would, especially with some of these finishes that are within tenths of a second. Wouldn't be surprising either, the Rio Olympics as a whole seem to be a mess, and I doubt most pool builders even consider it.
- diego_moita 10y ago
  > the Rio Olympics as a whole seem to be a mess, As a Brazilian let me ask this: because Munich 72 and Atlanta 96 where so much better ? (hint: no terrorism in Rio)
  - whack 10y ago
    Not sure why Diego is being downvoted so much, when parent who made an equally incendiary comment wasn't. Many respected "first world" journalists have also commented on the same pattern of people from richer countries condescending to poorer countries that host the Olympics. http://www.nytimes.com/2016/08/16/opinion/brazils-uplifting-olympics.html http://www.nytimes.com/2016/08/16/opinion/brazils-uplifting-...
    - tedunangst 10y ago
      Black September attacking the Olympic village was a less predictable event than many of the problems occurring in Rio, like chlorinating the diving pool with the wrong chemicals.
    - Dylan16807 10y ago
      >Not sure why Diego is being downvoted so much, when parent who made an equally incendiary comment wasn't. Because "tu quoque" is a lot more obnoxious than just calling something bad.
  - drivingmenuts 10y ago
    Apples to oranges. Both incidents you cite were third-parties directly trying to stage political disruptions by causing death and destruction. Rio is the government and other sponsors just plain failing to follow thru on commitments.
    - diego_moita 10y ago
      This is plain and simple prejudice and bullshit. The government has been following thru on commitments. * When Rio was announced people said the venues wouldn't be ready on time. They were. * When zika broke out people predicted an Olympic pandemic. Then came southern hemisphere winter and you're more likely to get zika in Florida than Rio. * When media discovered pollution in Guanabara Bay people asked for cancellation of events out of health concerns. No event was cancelled and no evidence of health hazards. * when a chemical imbalance turned a swimming pool green people called for cancellation. It turned out to be harmless algae. * when American swimmers claimed to be robbed a media uproar denounced a security chaos. Turns out they lied to hide a visit to a brothel. All of this is a continuation of a pattern. Rich countries freaked out with the Olympics in Beijing and Sochi too. Rio would have to endure the same.
      - rbritton 10y ago
        > * when American swimmers claimed to be robbed a media uproar denounced a security chaos. Turns out they lied to hide a visit to a brothel. Do you have a reference for this? I'm aware of the inconsistencies with the stories in this situation, but I've never seen a brothel mentioned anywhere.
        deleted 10y ago
        [deleted]
        no_cake 10y ago
        I believe he is talking about this. Still, no brothel mentioned. http://www.detroitnews.com/story/sports/olympics/2016/08/18/lochte-teammates-meet-authorities-over-reported-robbery/88943016/ http://www.detroitnews.com/story/sports/olympics/2016/08/18/...
  - shostack 10y ago
    I think there are a lot of differences here in terms of the level of blatant corruption, extreme disrespect shown by the Brazilian fans, insane crime reports, Zika, etc. There's a reason the /r/apocalympics subteddit is so popular.
    - diego_moita 10y ago
      > extreme disrespect shown by the Brazilian fans, insane crime reports, Zika, etc. Bullshit. There's more zika in Florida now than in Rio. There's more crime now in Detroit, New Orleans, St. Louis and Baltimore than Rio. And your "etc" was used for Beijing and Sochi too. This is just rich countries' snobbery. > There's a reason the /r/apocalympics subteddit is so popular. Yes, it is the fact that every subredit is a virtual linch mob or, as they say there, a circlejerk.
    - hamax 10y ago
      Apocalympics subreddit is so popular because people really like to feel superior.
  - maxerickson 10y ago
    no terrorism in Rio You must not be a bathroom door.
  - dominotw 10y ago
    I think they were great. Brazil did a great job given the circumstances. Boo-ing was the only thing that could have been totally avoided.
    - goodcanadian 10y ago
      I'm no expert, but it seems to me that the booing is mostly down to different cultural expectations (i.e. Brazilians don't necessarily see it as disrespectful): http://www.bbc.com/news/magazine-37026844 http://www.bbc.com/news/magazine-37026844
  - falsestprophet 10y ago
    Not having a terror attack is a pretty low bar.
    - cylinder 10y ago
      One Atlanta could not meet.
- madcorgi 10y ago
  50 m freestyle final. Manaudou, defending champion, came second to Ervin (previously gold medalist in the event) by 0.01. Ervin was in a more favorable lane according to the data (in 3 against Manaudou's 4). In such a short distance, the tiniest advantage becomes massive!
- Spooky23 10y ago
  The trains seem to be running on time. The feeling of messiness is generated by the vapid NBC coverage. The coverage of sports is so poor, I imagine that other, non-core coverage is garbage as well.
tbenst 10y ago
There is another plausible explanation: there are many people, especially photographers, near the turn for lanes 1-4 but none for 5-8. The start has people on both sides. The rest of the deck is barren. Even after 15 years of competitive swimming, the visual presence of yelling people still had impact on my effort level, while the presence of a stroke & turn judge leads to a tightening of form (ie less dolphin kick in breaststroke). Edit: of course, this could still be unfair but at least it would be due to human psyche rather than currents
- andars 10y ago
  Another idea: many of the swimmers breathe only to one side (in the races that they breathe at all), so in one direction they would be able to (better) see the faster swimmers towards the center. Another possible psychological factor.
  - sulam 10y ago
    Wouldn't both these factors be constant over multiple events? Why would they impact 2 events out of 5?
    - Pinatubo 10y ago
      It could depend on the particular layout of the pool deck at each event -- some allow people closer than others, etc.
    - gleenn 10y ago
      You breath differently for different events?
- kinofcain 10y ago
  It should be easy to check if the results are more or less skewed for back, breast, and fly events, where most swimmers do not favor a particular side.
- tedunangst 10y ago
  That's something to check, but seems unlikely. The effect is noticeable in freestyle, where it's kinda hard to DQ, and there's a judge in every lane (iirc), so there's no reason to slow down. The graphs make the effect look pretty linear, which doesn't fit with my model of sports psych. Shouldn't there also be a slight bump for lanes 7 and 8, because they're also closer to the smaller crowd on that side? Instead it's a straight slope straight across the pool. Is the inspiration boost that comes from moving from lane 2 to lane 1 equivalent to the boost from moving from 8 to 7? I'd expect some inverse square law to apply.
encoderer 10y ago
In any given lane, if I'm swimming with the current in one direction wouldn't I be swimming against it in the return?
- colanderman 10y ago
  Yes, that's the first topic in the article.
- phamilton 10y ago
  It's doesn't quite work that way. Oversimplifying it a bit. Imagine a swimmer swims 5m/s and the current adds/subtracts 1m/s. The pool is 50m. No current each length should take 10s. Going with the current takes 8.3s and going against the current takes 12.5 seconds. 100m takes 20.8s instead of 20s. Why? While the benefit/detriment ratio is 50-50 in terms of distance, it's not 50-50 in terms of time. You spend less time benefiting from the current because you are going faster. Alternatively, if the race was a fixed 10seconds in each direction you would go 60m and 40m, making it equivalent.
  - dzamo_norton 10y ago
    Yes. Imagine a current flowing exactly as fast as you can swim and you must swim one lap with it and one against it. You cover the lap in half your normal time when it's helping you and then when it's against you you cannot _even_ cover a lap. Total time = infinity.
    - sandworm101 10y ago
      >you must swim one lap with it and one against it. Lengths, not laps. A lap in running brings the runner around the track and back to where they started. A lap in swimming is from one side to the other and back again (100m). A length, from one side of the pool to the other, is 50m or half of a lap. If there is a current one length is different from another other, but the laps are identical.
  - encoderer 10y ago
    Fantastic answer. Thank you.
deleted 10y ago
[deleted]
jrudolph 10y ago
Fantastic analysis. One important question not covered in the article: how are lanes assigend in swimming? In rowing we have a qualification system that is geared to have the best crews start in the middle two of the 6 lanes, then going further out. For all I know about fluid dynamics, swimming in the outer lanes should have a disadvantage (swimming close to the pools boundary adds drag).
- NegativeLatency 10y ago
  In swimming your lane is determined by your seed time. In events with multiple heats it gets more complex, but the fastest people are in the middle lanes.
- imh 10y ago
  Lanes in swimming are according to speed. If you have the fastest prelim time, you're in lane 4. Second fastest in lane 5, then continuing down to 3,6,2,7,1,8. As for the boundary stuff, at the top meets, they don't have a swimmer in the lanes closest to the wall (https://www.youtube.com/watch?v=GXC4hYnH4n0 https://www.youtube.com/watch?v=GXC4hYnH4n0).
  - sandworm101 10y ago
    Wow, that is a tiny tiny pool. It's fine for kids, but seeing competitive swimmers racing across 25 yards is just funny. The doubled-up, yet still tiny lane ropes are also cute.
- sandworm101 10y ago
  Swimming immediately next to the wall, as in inches from it, can also have advantages. The fastest way of getting from one side of a pool to another is dolphin kicking along the bottom. The water coming off your stroke pushes against the solid surface, effectively giving you more 'grip' than you would have in open water.
- pimlottc 10y ago
  Note that, while there is a common perception among athletes that the middle lanes are advantageous (or at the least, preferable), there is not backed up by any scientific evidence: http://sports.stackexchange.com/questions/1326/in-swimming-is-there-a-competitive-advantage-to-being-in-one-lane-or-another http://sports.stackexchange.com/questions/1326/in-swimming-i... Of course, the prestige conferred by the established allocation system should also be considered as a factor explaining preferences as well...
grandalf 10y ago
Don't the swimmers get to choose their preferred lane based on qualifying times?
- andars 10y ago
  No. Fastest swimmers are seeded in the center lanes, slowest in the outside lanes.
dzdt 10y ago
The stats look really damning. Notice the p-scores : 4e-19 for worlds 2013 and 5e-8 for olympics 2016. And you can see it so clearly in the graphs too. No question, there was a big difference between one side of the pool and the other!
- Alex3917 10y ago
  Those aren't the stats that really matter though. At the end of the day, the question isn't whether the pool is fair or not, but whether the people watching the event on TV still go out and eat McDonalds or whatever afterwards. Most sports aren't really 'fair' per se. Making them fair wouldn't be cost effective, and wouldn't make for good TV. E.g. everyone knows that some lanes are faster than others in rowing due to the lack of wind screens around the venues. And that's not even to mention the people who spend ten years training only to get violently ill and unable to compete due to the water quality. The reality is that even at the highest levels of competition there is still a lot of luck.
  - 0xdeadbeefbabe 10y ago
    I'm annoyed by NBC's approach to streaming online where you have to login. I suppose they don't care about me, because I don't eat at McDonalds. Edit: Also you are right.
  - yodsanklai 10y ago
    > The reality is that even at the highest levels of competition there is still a lot of luck. It really depends on the sport. For instance, football (soccer) is very random, and this is amplified by the tournament format. But in many other sports, there is no suspens at all. Actually, it would be interesting to somehow evaluate the random factor for each sport.
    - pesfandiar 10y ago
      Even in sports with less variance in performance (e.g. weightlifting), we're only looking at one or very few data points. There are definitely random factors in the final outcome, but it may even add excitement to the events. That said, I still think fairness or at least perception of reasonable fairness is very important in high-level sports. No one is going to watch the games (or the ads as the GP pointed out) if they think the game's rigged.
sandworm101 10y ago
Take this from a former competitive swimmer (a not-slow one) now with 25+ years of lap swimming: This is far more complicated than the OP. Reasons for a current: (1) This is an outdoor pool. Sunlight is the death of chlorine in pools. The bigger the pool, the brighter the sun, the more chlorine is burnt off. The chlorine-related chemicals used in pools also do not properly dissolve in water. They slowly rise towards the surface. So when you turn off the circulation system, they rise towards that deadly sunlight. Given that, and the fact that they were having epic chlorine-related problems, it is of no surprise that they would have run the circulation systems as much as possible when the pool was not in use. But pool water doesn't stop instantly. A gyre may have formed and be stable for hours afterwards. Laneropes are meant to stop this, but they do little under the surface. (2) This is an outdoor pool, in direct sunlight, with the pumps off during the day ---> convection currents. And the circulation system is off. This is most interesting because as the sun rises one would expect an asymmetric current to form based on which side of the pool got the most sun. Normally this would be, in the southern hemisphere, the south west corner. I would expect an upwelling there along the wall, with a much lesser current across the pool surface from SW to NE. Effects of the current. Head/tailwinds aren't normally an issue. The faster one swims the lesser the effect. If this were happening we would see it in differences between length splits (fyi "length"=50m and "lap"=100m, many confuse those terms). I think up/down-welling currents are more at play. Fast swimmers rely on very specific stroke patterns. Slight perturbations in the water can throw off a swimmer's stroke. Imagine swimming past a water jet or upwelling and your hand is pushed sideways. That can slow you down far more than fighting a slight current. If I am correct, the greatest effect would be in the SW corner of the pool. Anyone know which lane that would be? In the footage, we should also see swimmers drifting (both left and right) when approaching that SW corner.
- _Wintermute 10y ago
  Umm. (1) It's an indoor pool. (2) The pumps are kept on.
  - sandworm101 10y ago
    http://www1.pictures.zimbio.com/gi/Rio+2016+Olympic+Games+President+Dilma+Rousseff+tOD11kV9sxGl.jpg http://www1.pictures.zimbio.com/gi/Rio+2016+Olympic+Games+Pr... See those windows. This is an outdoor pool under a temporary structure. Sunlight (UV) is coming in and air is circulating. And if the the pumps are running, they aren't at full power during races. Often at such events officials will state that pumps are run when they are in fact off. This is a common conflict between the needs of the event (stable water) and local health codes that dictate that circulation pumps remain on. In a 50m pool, if they are on they aren't 'on' enough to keep things mixed.
sambe 10y ago
I was puzzling over exactly this during Ledecky's win in the 800m. I watched a replay with constant WR graphic overlay, so you could see her gaining and losing ground on it. IIRC the BBC commentators also contradicted themselves more than once about whether she was going even better or about the same (without really realising something strange was going on). Try to catch a replay if you can.
- jessaustin 10y ago
  One really doubts they have good enough records to accurately draw that line. More probably they're just moving it at a generally constant speed, fudging a bit at the turns.
  - sambe 10y ago
    Right, it goes away for a second or so at the turn. But the pattern is pretty accurate, because at a minimum they have the splits.
latimer 10y ago
Here's the response from Myrtha Pools, the maker of the pool, that disputes that there were any current issues with the pool. https://swimswam.com/myrtha-pools-says-tests-showed-zero-hint-current-problem-rio/ https://swimswam.com/myrtha-pools-says-tests-showed-zero-hin...
- kinofcain 10y ago
  That's certainly a good data point in the 'against' column, but it really only indicates that any current, if present, isn't likely to be caused by the normal circulation of water from filtration systems or similar. There are a number of other things that could possibly be causing a current. For instance the current could be caused by the interaction between the pool and the motion of the swimmers in the pool. It could be caused by the overflow wave from 8 people entering the pool. It could be caused by uneven gutter heights leading to the pool draining at a faster rate on one side/corner. It could be a combination of all of these things, none of which would show up in a static test like the one they demonstrated. The fact that this has happened at some races and not others, and the ones it looks like it has happened at are Myrtha pools, is interesting in itself.
- sandworm101 10y ago
  Those tests are with floats. That may be the standard but it isn't appropriate imho. Swimmers do not swim in the top few inches of water. They swim as deep as four feet in dives, and are constantly dipping hands feet down two or more feet. Any current down there would go undetected by such a float, especially when it is surrounded by lane ropes. Do a test with something hanging below the float, below the protection of the lane ropes. Or drop some dye in the water. (I'm a little surprise by the wave action visible in these tests. With so many ropes, that water should be like glass very quickly.) There is some theatre here. Swimmers know the water moves, that it isn't a stationary tank. A perfect pool, with perfectly still water in every lane during an actual race, isn't possible. As slight winds can affect football games, swimmers just have to live with slight inconsistencies between lanes and pools.
kbenson 10y ago
Even with a circular current, there would be effects that don’t even out over the course of a long race. These add up to a few tenths of a second for the swimmers in the outer lanes of the 800 and the 1500. In a race that was decided by seconds, this would not have affected the final result ordering. But in a 50, a difference of a couple tenths of a second due to a push or a pull could be the difference between a medal and not. I few tenths of a second over 800 or 1500 meters should be (a few tenths of a second) / (800/50) or (a few tenths of a second) / (1500/50) when scaling it to the much smaller 50m, should it not? A few hundredths of a second, or even a few thousandths of a second, given that there's an order of magnitude difference.
- IanCal 10y ago
  I think they were saying that many of the effects cancel out over multiple lengths, as you're slowed down one way and sped up the other. It's not a perfect cancellation but it does diminish the problem. However the 50m is just one way, so you get the entire effect with nothing cancelling it out at all. There's also then a much bigger difference between lane 1 and 8. If everyone did two lengths, then lanes 1 and 8 would have been penalised a bit (faster one way, slower the other) but they'd have done the same as each other. Lanes 4&5 would have been a bit better. Now picture just one length. Lane 1 never has to swim against the current, while lane 8 has to fight it all the way.
  - kbenson 10y ago
    I agree with your reasoning about how it could affect a one way race, but if that was actually the intention of the referenced portion of the article, I think they went about it in a very confusing manner at best.
misnome 10y ago
Ah - I'm glad this is about a different incident than when the diving pool turned bright green. Which I'd suspect would classify as a problem.
zizzles 10y ago
The amount of dilemmas surrounding Rio 2016 is staggering. From polluted rivers that leave rowers sick to muggings and now this: poorly designed swimming pools? Brazilians are disappointing me.
- escoz 10y ago
  fyi the pool was built by an american company.
- gerbilly 10y ago
  It looks like the us swimmers lied about being mugged to cover up their acts of vandalism. http://www.newshub.co.nz/world/us-swimmers-lied-about-mugging-after-vandalising-bathroom-2016081907 http://www.newshub.co.nz/world/us-swimmers-lied-about-muggin...
  - zaroth 10y ago
    NY Times reports that the "public officer" (actually an off duty prison guard) did brandish a gun, and demanded money. Vandalism or not, that's precisely the definition of armed robbery. Lochte certainly lied about the details, but two wrongs don't make a right, and only one of these wrongs carries up to a 20 year sentence with a 5 year minimum, at least in the US.
brianpgordon 10y ago
WSJ article: http://www.wsj.com/articles/did-the-olympic-pool-give-some-swimmers-an-advantage-1471470741?mod=trending_now_2 http://www.wsj.com/articles/did-the-olympic-pool-give-some-s...

229 points by furyg3 10y ago

Vexs 10y ago

That seems pretty damning to me personally, but I'm not a statistician. It's also something I would never think could give an advantage, but I guess it makes sense that it would, especially with some of these finishes that are within tenths of a second. Wouldn't be surprising either, the Rio Olympics as a whole seem to be a mess, and I doubt most pool builders even consider it.

diego_moita 10y ago
> the Rio Olympics as a whole seem to be a mess, As a Brazilian let me ask this: because Munich 72 and Atlanta 96 where so much better ? (hint: no terrorism in Rio)
- whack 10y ago
  Not sure why Diego is being downvoted so much, when parent who made an equally incendiary comment wasn't. Many respected "first world" journalists have also commented on the same pattern of people from richer countries condescending to poorer countries that host the Olympics. http://www.nytimes.com/2016/08/16/opinion/brazils-uplifting-olympics.html http://www.nytimes.com/2016/08/16/opinion/brazils-uplifting-...
  - tedunangst 10y ago
    Black September attacking the Olympic village was a less predictable event than many of the problems occurring in Rio, like chlorinating the diving pool with the wrong chemicals.
  - Dylan16807 10y ago
    >Not sure why Diego is being downvoted so much, when parent who made an equally incendiary comment wasn't. Because "tu quoque" is a lot more obnoxious than just calling something bad.
- drivingmenuts 10y ago
  Apples to oranges. Both incidents you cite were third-parties directly trying to stage political disruptions by causing death and destruction. Rio is the government and other sponsors just plain failing to follow thru on commitments.
  - diego_moita 10y ago
    This is plain and simple prejudice and bullshit. The government has been following thru on commitments. * When Rio was announced people said the venues wouldn't be ready on time. They were. * When zika broke out people predicted an Olympic pandemic. Then came southern hemisphere winter and you're more likely to get zika in Florida than Rio. * When media discovered pollution in Guanabara Bay people asked for cancellation of events out of health concerns. No event was cancelled and no evidence of health hazards. * when a chemical imbalance turned a swimming pool green people called for cancellation. It turned out to be harmless algae. * when American swimmers claimed to be robbed a media uproar denounced a security chaos. Turns out they lied to hide a visit to a brothel. All of this is a continuation of a pattern. Rich countries freaked out with the Olympics in Beijing and Sochi too. Rio would have to endure the same.
    - rbritton 10y ago
      > * when American swimmers claimed to be robbed a media uproar denounced a security chaos. Turns out they lied to hide a visit to a brothel. Do you have a reference for this? I'm aware of the inconsistencies with the stories in this situation, but I've never seen a brothel mentioned anywhere.
      - deleted 10y ago
        [deleted]
      - no_cake 10y ago
        I believe he is talking about this. Still, no brothel mentioned. http://www.detroitnews.com/story/sports/olympics/2016/08/18/lochte-teammates-meet-authorities-over-reported-robbery/88943016/ http://www.detroitnews.com/story/sports/olympics/2016/08/18/...
- shostack 10y ago
  I think there are a lot of differences here in terms of the level of blatant corruption, extreme disrespect shown by the Brazilian fans, insane crime reports, Zika, etc. There's a reason the /r/apocalympics subteddit is so popular.
  - diego_moita 10y ago
    > extreme disrespect shown by the Brazilian fans, insane crime reports, Zika, etc. Bullshit. There's more zika in Florida now than in Rio. There's more crime now in Detroit, New Orleans, St. Louis and Baltimore than Rio. And your "etc" was used for Beijing and Sochi too. This is just rich countries' snobbery. > There's a reason the /r/apocalympics subteddit is so popular. Yes, it is the fact that every subredit is a virtual linch mob or, as they say there, a circlejerk.
  - hamax 10y ago
    Apocalympics subreddit is so popular because people really like to feel superior.
- maxerickson 10y ago
  no terrorism in Rio You must not be a bathroom door.
- dominotw 10y ago
  I think they were great. Brazil did a great job given the circumstances. Boo-ing was the only thing that could have been totally avoided.
  - goodcanadian 10y ago
    I'm no expert, but it seems to me that the booing is mostly down to different cultural expectations (i.e. Brazilians don't necessarily see it as disrespectful): http://www.bbc.com/news/magazine-37026844 http://www.bbc.com/news/magazine-37026844
- falsestprophet 10y ago
  Not having a terror attack is a pretty low bar.
  - cylinder 10y ago
    One Atlanta could not meet.
madcorgi 10y ago
50 m freestyle final. Manaudou, defending champion, came second to Ervin (previously gold medalist in the event) by 0.01. Ervin was in a more favorable lane according to the data (in 3 against Manaudou's 4). In such a short distance, the tiniest advantage becomes massive!
Spooky23 10y ago
The trains seem to be running on time. The feeling of messiness is generated by the vapid NBC coverage. The coverage of sports is so poor, I imagine that other, non-core coverage is garbage as well.

tbenst 10y ago

There is another plausible explanation: there are many people, especially photographers, near the turn for lanes 1-4 but none for 5-8. The start has people on both sides. The rest of the deck is barren. Even after 15 years of competitive swimming, the visual presence of yelling people still had impact on my effort level, while the presence of a stroke & turn judge leads to a tightening of form (ie less dolphin kick in breaststroke). Edit: of course, this could still be unfair but at least it would be due to human psyche rather than currents

andars 10y ago
Another idea: many of the swimmers breathe only to one side (in the races that they breathe at all), so in one direction they would be able to (better) see the faster swimmers towards the center. Another possible psychological factor.
- sulam 10y ago
  Wouldn't both these factors be constant over multiple events? Why would they impact 2 events out of 5?
  - Pinatubo 10y ago
    It could depend on the particular layout of the pool deck at each event -- some allow people closer than others, etc.
  - gleenn 10y ago
    You breath differently for different events?
kinofcain 10y ago
It should be easy to check if the results are more or less skewed for back, breast, and fly events, where most swimmers do not favor a particular side.
tedunangst 10y ago
That's something to check, but seems unlikely. The effect is noticeable in freestyle, where it's kinda hard to DQ, and there's a judge in every lane (iirc), so there's no reason to slow down. The graphs make the effect look pretty linear, which doesn't fit with my model of sports psych. Shouldn't there also be a slight bump for lanes 7 and 8, because they're also closer to the smaller crowd on that side? Instead it's a straight slope straight across the pool. Is the inspiration boost that comes from moving from lane 2 to lane 1 equivalent to the boost from moving from 8 to 7? I'd expect some inverse square law to apply.

encoderer 10y ago

In any given lane, if I'm swimming with the current in one direction wouldn't I be swimming against it in the return?

colanderman 10y ago
Yes, that's the first topic in the article.
phamilton 10y ago
It's doesn't quite work that way. Oversimplifying it a bit. Imagine a swimmer swims 5m/s and the current adds/subtracts 1m/s. The pool is 50m. No current each length should take 10s. Going with the current takes 8.3s and going against the current takes 12.5 seconds. 100m takes 20.8s instead of 20s. Why? While the benefit/detriment ratio is 50-50 in terms of distance, it's not 50-50 in terms of time. You spend less time benefiting from the current because you are going faster. Alternatively, if the race was a fixed 10seconds in each direction you would go 60m and 40m, making it equivalent.
- dzamo_norton 10y ago
  Yes. Imagine a current flowing exactly as fast as you can swim and you must swim one lap with it and one against it. You cover the lap in half your normal time when it's helping you and then when it's against you you cannot _even_ cover a lap. Total time = infinity.
  - sandworm101 10y ago
    >you must swim one lap with it and one against it. Lengths, not laps. A lap in running brings the runner around the track and back to where they started. A lap in swimming is from one side to the other and back again (100m). A length, from one side of the pool to the other, is 50m or half of a lap. If there is a current one length is different from another other, but the laps are identical.
- encoderer 10y ago
  Fantastic answer. Thank you.

deleted 10y ago

[deleted]

jrudolph 10y ago

Fantastic analysis. One important question not covered in the article: how are lanes assigend in swimming? In rowing we have a qualification system that is geared to have the best crews start in the middle two of the 6 lanes, then going further out. For all I know about fluid dynamics, swimming in the outer lanes should have a disadvantage (swimming close to the pools boundary adds drag).

NegativeLatency 10y ago
In swimming your lane is determined by your seed time. In events with multiple heats it gets more complex, but the fastest people are in the middle lanes.
imh 10y ago
Lanes in swimming are according to speed. If you have the fastest prelim time, you're in lane 4. Second fastest in lane 5, then continuing down to 3,6,2,7,1,8. As for the boundary stuff, at the top meets, they don't have a swimmer in the lanes closest to the wall (https://www.youtube.com/watch?v=GXC4hYnH4n0 https://www.youtube.com/watch?v=GXC4hYnH4n0).
- sandworm101 10y ago
  Wow, that is a tiny tiny pool. It's fine for kids, but seeing competitive swimmers racing across 25 yards is just funny. The doubled-up, yet still tiny lane ropes are also cute.
sandworm101 10y ago
Swimming immediately next to the wall, as in inches from it, can also have advantages. The fastest way of getting from one side of a pool to another is dolphin kicking along the bottom. The water coming off your stroke pushes against the solid surface, effectively giving you more 'grip' than you would have in open water.
pimlottc 10y ago
Note that, while there is a common perception among athletes that the middle lanes are advantageous (or at the least, preferable), there is not backed up by any scientific evidence: http://sports.stackexchange.com/questions/1326/in-swimming-is-there-a-competitive-advantage-to-being-in-one-lane-or-another http://sports.stackexchange.com/questions/1326/in-swimming-i... Of course, the prestige conferred by the established allocation system should also be considered as a factor explaining preferences as well...

grandalf 10y ago

Don't the swimmers get to choose their preferred lane based on qualifying times?

andars 10y ago
No. Fastest swimmers are seeded in the center lanes, slowest in the outside lanes.

dzdt 10y ago

The stats look really damning. Notice the p-scores : 4e-19 for worlds 2013 and 5e-8 for olympics 2016. And you can see it so clearly in the graphs too. No question, there was a big difference between one side of the pool and the other!

Alex3917 10y ago
Those aren't the stats that really matter though. At the end of the day, the question isn't whether the pool is fair or not, but whether the people watching the event on TV still go out and eat McDonalds or whatever afterwards. Most sports aren't really 'fair' per se. Making them fair wouldn't be cost effective, and wouldn't make for good TV. E.g. everyone knows that some lanes are faster than others in rowing due to the lack of wind screens around the venues. And that's not even to mention the people who spend ten years training only to get violently ill and unable to compete due to the water quality. The reality is that even at the highest levels of competition there is still a lot of luck.
- 0xdeadbeefbabe 10y ago
  I'm annoyed by NBC's approach to streaming online where you have to login. I suppose they don't care about me, because I don't eat at McDonalds. Edit: Also you are right.
- yodsanklai 10y ago
  > The reality is that even at the highest levels of competition there is still a lot of luck. It really depends on the sport. For instance, football (soccer) is very random, and this is amplified by the tournament format. But in many other sports, there is no suspens at all. Actually, it would be interesting to somehow evaluate the random factor for each sport.
  - pesfandiar 10y ago
    Even in sports with less variance in performance (e.g. weightlifting), we're only looking at one or very few data points. There are definitely random factors in the final outcome, but it may even add excitement to the events. That said, I still think fairness or at least perception of reasonable fairness is very important in high-level sports. No one is going to watch the games (or the ads as the GP pointed out) if they think the game's rigged.

sandworm101 10y ago

Take this from a former competitive swimmer (a not-slow one) now with 25+ years of lap swimming: This is far more complicated than the OP. Reasons for a current: (1) This is an outdoor pool. Sunlight is the death of chlorine in pools. The bigger the pool, the brighter the sun, the more chlorine is burnt off. The chlorine-related chemicals used in pools also do not properly dissolve in water. They slowly rise towards the surface. So when you turn off the circulation system, they rise towards that deadly sunlight. Given that, and the fact that they were having epic chlorine-related problems, it is of no surprise that they would have run the circulation systems as much as possible when the pool was not in use. But pool water doesn't stop instantly. A gyre may have formed and be stable for hours afterwards. Laneropes are meant to stop this, but they do little under the surface. (2) This is an outdoor pool, in direct sunlight, with the pumps off during the day ---> convection currents. And the circulation system is off. This is most interesting because as the sun rises one would expect an asymmetric current to form based on which side of the pool got the most sun. Normally this would be, in the southern hemisphere, the south west corner. I would expect an upwelling there along the wall, with a much lesser current across the pool surface from SW to NE. Effects of the current. Head/tailwinds aren't normally an issue. The faster one swims the lesser the effect. If this were happening we would see it in differences between length splits (fyi "length"=50m and "lap"=100m, many confuse those terms). I think up/down-welling currents are more at play. Fast swimmers rely on very specific stroke patterns. Slight perturbations in the water can throw off a swimmer's stroke. Imagine swimming past a water jet or upwelling and your hand is pushed sideways. That can slow you down far more than fighting a slight current. If I am correct, the greatest effect would be in the SW corner of the pool. Anyone know which lane that would be? In the footage, we should also see swimmers drifting (both left and right) when approaching that SW corner.

_Wintermute 10y ago
Umm. (1) It's an indoor pool. (2) The pumps are kept on.
- sandworm101 10y ago
  http://www1.pictures.zimbio.com/gi/Rio+2016+Olympic+Games+President+Dilma+Rousseff+tOD11kV9sxGl.jpg http://www1.pictures.zimbio.com/gi/Rio+2016+Olympic+Games+Pr... See those windows. This is an outdoor pool under a temporary structure. Sunlight (UV) is coming in and air is circulating. And if the the pumps are running, they aren't at full power during races. Often at such events officials will state that pumps are run when they are in fact off. This is a common conflict between the needs of the event (stable water) and local health codes that dictate that circulation pumps remain on. In a 50m pool, if they are on they aren't 'on' enough to keep things mixed.

sambe 10y ago

I was puzzling over exactly this during Ledecky's win in the 800m. I watched a replay with constant WR graphic overlay, so you could see her gaining and losing ground on it. IIRC the BBC commentators also contradicted themselves more than once about whether she was going even better or about the same (without really realising something strange was going on). Try to catch a replay if you can.

jessaustin 10y ago
One really doubts they have good enough records to accurately draw that line. More probably they're just moving it at a generally constant speed, fudging a bit at the turns.
- sambe 10y ago
  Right, it goes away for a second or so at the turn. But the pattern is pretty accurate, because at a minimum they have the splits.

latimer 10y ago

Here's the response from Myrtha Pools, the maker of the pool, that disputes that there were any current issues with the pool. https://swimswam.com/myrtha-pools-says-tests-showed-zero-hint-current-problem-rio/ https://swimswam.com/myrtha-pools-says-tests-showed-zero-hin...

kinofcain 10y ago
That's certainly a good data point in the 'against' column, but it really only indicates that any current, if present, isn't likely to be caused by the normal circulation of water from filtration systems or similar. There are a number of other things that could possibly be causing a current. For instance the current could be caused by the interaction between the pool and the motion of the swimmers in the pool. It could be caused by the overflow wave from 8 people entering the pool. It could be caused by uneven gutter heights leading to the pool draining at a faster rate on one side/corner. It could be a combination of all of these things, none of which would show up in a static test like the one they demonstrated. The fact that this has happened at some races and not others, and the ones it looks like it has happened at are Myrtha pools, is interesting in itself.
sandworm101 10y ago
Those tests are with floats. That may be the standard but it isn't appropriate imho. Swimmers do not swim in the top few inches of water. They swim as deep as four feet in dives, and are constantly dipping hands feet down two or more feet. Any current down there would go undetected by such a float, especially when it is surrounded by lane ropes. Do a test with something hanging below the float, below the protection of the lane ropes. Or drop some dye in the water. (I'm a little surprise by the wave action visible in these tests. With so many ropes, that water should be like glass very quickly.) There is some theatre here. Swimmers know the water moves, that it isn't a stationary tank. A perfect pool, with perfectly still water in every lane during an actual race, isn't possible. As slight winds can affect football games, swimmers just have to live with slight inconsistencies between lanes and pools.

kbenson 10y ago

Even with a circular current, there would be effects that don’t even out over the course of a long race. These add up to a few tenths of a second for the swimmers in the outer lanes of the 800 and the 1500. In a race that was decided by seconds, this would not have affected the final result ordering. But in a 50, a difference of a couple tenths of a second due to a push or a pull could be the difference between a medal and not. I few tenths of a second over 800 or 1500 meters should be (a few tenths of a second) / (800/50) or (a few tenths of a second) / (1500/50) when scaling it to the much smaller 50m, should it not? A few hundredths of a second, or even a few thousandths of a second, given that there's an order of magnitude difference.

IanCal 10y ago
I think they were saying that many of the effects cancel out over multiple lengths, as you're slowed down one way and sped up the other. It's not a perfect cancellation but it does diminish the problem. However the 50m is just one way, so you get the entire effect with nothing cancelling it out at all. There's also then a much bigger difference between lane 1 and 8. If everyone did two lengths, then lanes 1 and 8 would have been penalised a bit (faster one way, slower the other) but they'd have done the same as each other. Lanes 4&5 would have been a bit better. Now picture just one length. Lane 1 never has to swim against the current, while lane 8 has to fight it all the way.
- kbenson 10y ago
  I agree with your reasoning about how it could affect a one way race, but if that was actually the intention of the referenced portion of the article, I think they went about it in a very confusing manner at best.

misnome 10y ago

Ah - I'm glad this is about a different incident than when the diving pool turned bright green. Which I'd suspect would classify as a problem.

zizzles 10y ago

The amount of dilemmas surrounding Rio 2016 is staggering. From polluted rivers that leave rowers sick to muggings and now this: poorly designed swimming pools? Brazilians are disappointing me.

escoz 10y ago
fyi the pool was built by an american company.
gerbilly 10y ago
It looks like the us swimmers lied about being mugged to cover up their acts of vandalism. http://www.newshub.co.nz/world/us-swimmers-lied-about-mugging-after-vandalising-bathroom-2016081907 http://www.newshub.co.nz/world/us-swimmers-lied-about-muggin...
- zaroth 10y ago
  NY Times reports that the "public officer" (actually an off duty prison guard) did brandish a gun, and demanded money. Vandalism or not, that's precisely the definition of armed robbery. Lochte certainly lied about the details, but two wrongs don't make a right, and only one of these wrongs carries up to a 20 year sentence with a 5 year minimum, at least in the US.

brianpgordon 10y ago

WSJ article: http://www.wsj.com/articles/did-the-olympic-pool-give-some-swimmers-an-advantage-1471470741?mod=trending_now_2 http://www.wsj.com/articles/did-the-olympic-pool-give-some-s...