What Makes 'Fast Pools' Fast?

Both the Water Cube from the 2008 Beijing Olympics and the Aquatic Centre from the London 2012 Olympics made a big splash in the swimming world at their unveiling. And not just because of their sleek, futuristic looks.
Instead, all the fuss was because they are fast pools.
Now, I know what you’re thinking. How can a pool be fast?
Technically speaking, they aren’t. Fast pools are engineered to reduce the factors that slow swimmers down, allowing them to swim easier, and therefore faster. And some of the designs are quite ingenious.
Here, we de-mystify some of the secrets behind how these hi-tech fast pools work.
 

Size

One of the biggest differences between normal pools and fast pools is their size. Fast pools are built both deeper and wider than normal pools.
The increased depth helps to reduce wave interference. Every time a swimmer strokes or kicks they create waves. Some of these waves travel down, bounce off the bottom and then travel back up. In a shallower pool, swimmers then have to swim through these waves when they come back up.
By making the pool deeper (the London pool is 10 ft. deep), these waves have to travel further before coming back up and most dissipate before they create any disturbance for the swimmers. The result is a calmer pool.
Fast pools are also wider (London pool- 82 ft). The other type of waves that swimmers create travel sideways across the pool. This means that swimmers are too close, they have to swim through waves created by their neighbors. Having an extra wide pool allows the swimmers to have a spacious lane.

It also allows for more lanes. Having extra lanes means it is possible to leave the two outside lanes empty. Just like the downward waves bounce off the bottom, the sideways waves bounce off the sides of the pool. Therefore, the lanes right next to the sides end up with extra turbulence as the waves bounce back- a disadvantage no one wants during a race.

 

Water Flow

Another big difference in fast pools is the way they are designed to control the flow of water through the pool.
All pools constantly recirculate the water to maintain sanitation. In a normal pool, new water is pumped into the pool through the sides. This creates currents that swimmers have to push through. In fast pools, the water is pumped in from the bottom of the pool so the currents created aren’t in the swimmers’ way.
Fast pools also have special gutters. Remember those pesky sideways waves that bounce off the sides of the pool? The gutters in a fast pool help absorb those waves. Basically, they’re troughs that run around the side of pool, even with the top of the water. So when a wave reaches the edge, it continues over the edge of the pool and falls into the trough. Once the water’s in the gutter, it can’t bounce back.
 

extras

Fast pools aren’t just about big differences. They also pay attention to the little details.
For example, the little plastic circles that make up lane dividers each spin. So when a wave crosses them, the wave’s energy is used to spin the circles instead of traveling farther. This energy-absorption helps reduce wave disturbance between lanes.

Another detail is the temperature of the water. If the pool water is too cold, the swimmer tenses when they enter the water. Being tense means more work to swim fast. On the other hand, if the water is too warm, swimmers will overheat and burnout quicker. So what’s the ideal? Apparently it’s 26° C (78° F).

 

Your Turn

Have you ever swam in a fast pool?
Is swimming in a fast pool on your bucket list?
 


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