Why are shallow swimming pools slow?
Having been a professional swimming coach for 12 years, I would regularly hear kids and adults say that a pool is slow or fast. In my personal experience I set a lot of my best times in a pool that had a minimum depth of 2m, far deeper than many local to me. But how can that be?
It’s just water, after all.
It’s not about the water itself but how it moves in a smaller space.
What makes a shallow swimming pool ‘slow’?
- The lesser depth gives waves under the water less space to dissipate. Instead, they are deflected back up towards the surface, causing more turbulence for the swimmer.
- When underwater out of turns, swimmers are unable to get sufficiently deep enough to get under the wave drag they created swimming into the wall.
- The increased turbulence caused by wave deflection negatively affects how much propulsion the swimmer can generate. More waves and white water mean less clear water to get hold of.
- If a swimmer is too close to the floor off the start or turn and touches the floor, it can also reduce their propulsion.
So, if you want to squeeze every hundredth of a second out of your swim speed, aim to do it in a pool at least 2.5-3m deep!
