
Was There a Problem with the Rio Pool? - furyg3
https://swimswam.com/problem-rio-pool/
======
tbenst
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
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
Wouldn't both these factors be constant over multiple events? Why would they
impact 2 events out of 5?

~~~
Pinatubo
It could depend on the particular layout of the pool deck at each event --
some allow people closer than others, etc.

------
latimer
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-
hin...](https://swimswam.com/myrtha-pools-says-tests-showed-zero-hint-current-
problem-rio/)

~~~
kinofcain
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
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
Umm.

(1) It's an indoor pool.

(2) The pumps are kept on.

~~~
misthop
Open air stadium[0]

[0][http://www.unrealitytv.co.uk/wp-
content/uploads/2016/08/olym...](http://www.unrealitytv.co.uk/wp-
content/uploads/2016/08/olympicpool.jpg)

~~~
JshWright
That's the diving/water polo/synchronized swimming venue.

------
Vexs
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
> 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
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-...](http://www.nytimes.com/2016/08/16/opinion/brazils-uplifting-
olympics.html)

~~~
tedunangst
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.

------
jrudolph
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).

~~~
imh
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
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.

------
dzdt
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
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.

~~~
yodsanklai
> 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.

~~~
mamon
Some even argue that the randomness of football (which Americans know by
riddiculous name "soccer") is the main factor that makes it the single most
popular sport in the world. Some unlucky events end up being remembered for
generations.

For example people in Poland are still discussing over the beer whether we
would have been world champions if only it hasn't been raining so heaviliy
during Poland - West Germany semi-final in 1974.

P.S English is not my language and I'm pretty sure I messed up with
conditionals, hope you still get what I meant in the last sentence.

~~~
evincarofautumn
The name “soccer” is just an old British slang abbreviation of “Association
Football”, to differentiate it from other kinds of football (that is, games
played on foot, as opposed to horseback—compare “footrace”). You can find old
references to “Rugby football” and “rugger” as well. Americans kept the term,
Brits didn’t.

[http://www.todayifoundout.com/index.php/2010/06/the-
origin-o...](http://www.todayifoundout.com/index.php/2010/06/the-origin-of-
the-word-soccer/)

~~~
jacinda
Exactly. And America isn't the only country that kept the abbreviation.
Australia, Ireland, Canada and some countries in Southern Africa use the same
term.

[http://deadspin.com/map-what-every-country-calls-the-
thing-w...](http://deadspin.com/map-what-every-country-calls-the-thing-we-
call-soccer-1491638984)

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

~~~
phamilton
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
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
>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.

------
kbenson
_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
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
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_.

------
sambe
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
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
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.

------
misnome
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.

------
brianpgordon
WSJ article:

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

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

~~~
andars
No. Fastest swimmers are seeded in the center lanes, slowest in the outside
lanes.

------
zizzles
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.

~~~
gerbilly
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-
muggin...](http://www.newshub.co.nz/world/us-swimmers-lied-about-mugging-
after-vandalising-bathroom-2016081907)

~~~
zaroth
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.

