I keep seeing people talking about how swimming records aren’t being broken on these Olympics because of the pools being too deep.
In: Physics
It’s the other way around, the complaint is that the pools in Paris are too *shallow*. First, you have to keep in mind that at the highest levels, sports like swimming are decided by fractions of a second, so even mild effects from the environment matter.
The optimal depth suggested by most international swimming bodies seems to be 3 meters, the ones in Paris are 2.15 meters, that’s the concern. As to why, swimmers produce pressure waves when they move through the water (essentially sound waves in water) and those waves reflect from the bottom of the pool and can very slightly slow them down by increasing turbulence in their strokes. The result is that a ‘shallow’ pool will generally lead to slightly slower speeds on average.
> When the Paris pool design was permitted, the World Aquatics minimum depth requirement for Olympic competition swimming was 2.0 meters. Although the World Aquatics facilities standards recommend a depth of 3.0 meters, this recommendation is often tied to multi-discipline use, such as Artistic Swimming. Since the time that the Paris installation was permitted, World Aquatics has increased the minimum depth requirement for Olympic competition to 2.5 meters.
https://www.aquaticsintl.com/facilities/balancing-speed-and-experience-optimal-pool-depth-for-competitive-swimming_o
Imagine a powered windmill in a pool. As it spins, it pushes the water down and away. If you were under water, you would feel these waves of water going past you.
Now if the pool is too shallow, those waves will hit the bottom of the pool and bounce back up, up to the windmill! This would slow it down because it would push back.
That’s kind of what’s happening at the Olympics. The pool is more shallow than usual, so the waves the swimmers are making are bouncing back and making it harder to swim.
The Paris pool is 2.15 meters. It was built when the rule was a minimum of 2 meters. Most pools are 3 meters deep. The deeper the pool, the more/further the water displacement can be distributed. The Paris pool doesn’t have as much room for the displacement and the swimmers are having to work harder to move.
It’s the opposite, deeper pools are considered faster because they’re less turbulent.
Swimmers create wake just like a boat does, that water then moves and bounces off the walls and bottom. Deeper/wider pools give that water more time to slow down and dissipate so it doesn’t impact the swimmers as much. You want the water as still as possible while you’re swimming so you can get a good “grip” on your pull, if the water you’re swimming through is choppy you’ll be less efficient. It’s minor, but it adds up over the course of a race.
The recommended depth for an Olympic size pool is 3m, the pool in France is like 2.1m or something.
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