Which Is Better for Speed: Salt Water or a Chlorinated Pool?

In the world of competitive swimming, thousandths of a second can make the difference between getting a record-breaking time or not. For maximum speed, swimmers would do well to be in salt water.

    Significance

    • Buoyancy is affected by the density of a liquid. Because salt water has extra materials dissolved in the water (which themselves are denser than water), the density of salt water is higher.

    Efficiency

    • High buoyancy helps objects float in a liquid. Greater positive buoyancy is helpful to swimmers; less energy has to be used to stay above the water, so more power can be directed forward, creating greater total thrust.

    Potential

    • More buoyant objects stay higher above the water-line. Since air resistance is thousands of times less than water resistance, a swimmer's movement will be less impeded the higher she floats in water.

    Theories/Speculation

    • Since the water being moved is more dense, it is also requires more energy to move out of the way. It is difficult to say whether the greater buoyancy would outweigh the increased resistance of the water, and would depend on which stroke is performed.

    Comparisons

    • Many people now have pools that are treated with small amounts of salt to keep them clean. These pools have radically less salt in them than most natural bodies of salt water, like the ocean. As such, the difference between fresh water and the salt-water treated pools will be less significant than would be fresh vs ocean water.