Training

Why Are Some Pools Faster Than Others?

If some pools seem fast, it might not be just in your head. A number of factors contribute to making a pool fast or slow.

After so many weeks out of the water due to the global pandemic, many of us have been desperately looking for reasons (some might say excuses?) why we’re swimming slowly. While the main reason is obvious (err, you’ve not been swimming for weeks!), there is actually some validity in looking at the pool where you swim. If you’ve ever got out of the water and thought “Dang, what’s wrong with me, why am I swimming so slowly today?” then there is some good news for you: it might not be you. Not all swimming pools are created equal. Some are slower and some are faster than others.

Factors such as the depth of the pool, water temperature, gutter design, lane ropes, and lane width—and even the number of the people in the pool—can all affect your swim speed. And it might sound like hocus pocus, but there are some athletes and coaches who believe that once fast times have been posted at a pool it can carry a certain stature and mystique: “It’s a fast pool, you’ll swim fast there”—and so success breeds success. 

But before we dive into the less-scientific reasons, we spoke to some top swim coaches to get their views on the main factors that really make a pool fast.

What Makes A Pool Fast: The Depth

Sara McLarty, a former pro swimmer and triathlete who is now head coach and owner of Florida-based Swim Like A Pro, said the depth of the water is an important factor to consider. 

“Shallow pools are actually slow because the water currents bounce back into you, but super deep pools, like swimming in a diving well, often feel slow because you don’t see the bottom moving under you as quickly,” she said.

Shallow pools generally tend to be more wavy or turbulent, because waves bounce off the bottom, creating turbulence. Generally speaking, calmer water equals faster water. However, very deep pools are not always faster, as McLarty said, because they don’t give you a point of reference. The “happy medium” is water depth of approximately 10 feet (the Olympic standard is 9.84 feet or three meters), which provides enough depth for waves to be reduced while also allowing the swimmer to see the pool floor and give them a point of reference. 

What Makes A Pool Fast: The Gutters And Lanes

The gutter design of a pool can have a significant impact on a pool’s “fast feeling” too. A pool with a perimeter overflow gutter will absorb waves, thereby reducing the water turbulence and enabling faster swimming. There’s a reason the fancy Olympic pools all seem to have high-tech gutters that make the waves disappear.

The same can be said of lane ropes; wide, durable “anti-wave” lane ropes will help absorb the wake from lane to lane and help create much faster conditions than thin lane lines that do little to quell waves from one lane to the next. Lane width can play a part here too, with wider lanes producing faster conditions than thinner lanes. 

What Makes A Pool Fast: The Temperature And Water Quality

Water temperature is another key factor to consider, especially when water is too warm. “In Florida in the summer, our outdoor pools get quite warm and pool temperature is an easy one to attribute to slower swimming/overheating,” she said. The official water temperature for competition is considered to be between 78 to 80 degrees F. Anything colder can make it hard to swim well (if at all!) and temperatures above this largely lead to overheating. 

“Pools can also feel slow when they are murky with poor water clarity or when the chemicals are a bit off,” McLarty said. “I get a lot of complaints from my athletes when the chemicals are off because they are more focused on complaining about the “cotton mouth” feeling.” The circulatory system of a pool can contribute to poor air circulation of the chemicals, making it harder for swimmers to breathe.

She added: “Indoor pools can have a real and imagined effect. If it’s dark and not spacious, I feel slow, because it’s a bit claustrophobic. Poor air circulation of the chemicals can make it harder to breathe too.”

Some Of It’s In Your Head

Coach Jim Vance believes the quality of the facility and the “mystique” surrounding it “generally leads to better results.” 

“When you’re at a pool that you know has produced a lot of fast times or that some of the best in the world train at, you can’t help but take your swimming more seriously and focus more. This generally leads to better results,” he said.

“I’ve coached a number of years in camps with Ben Kanute and other triathletes at a high school pool, which just excites people to get in the water and swim fast. It sounds a little hokey, but I see it where athletes are intimidated in that type of environment, and others really embrace it and enhance their focus and dedication.”