The Hydrodynamics of Wearing a Swim Cap

Swimmers would know the importance of wearing personalised swim caps but we’ll discuss further the hydrodynamics of wearing it.

Olympians and other professional swimmers wear swim caps because they swim faster during competition. Some people may think that this is considered an aerodynamics issue. However, aerodynamics applies to how things move through the air and in the water, it equates to hydrodynamics.

Water Resistance

There are three types of drag swimmers encounter whenever they swim such as form resistance, wave resistance, and friction. Wave resistance is created by the turbulence in the water, form resistance, on the other hand, is created by how your body is positioned in the water, and friction is created by how the water moves against your hair and skin. Friction can be the least powerful of these three, but it can still slow you down.

Capping the Friction

Swimmers wear caps because it helps reduce the friction resistance and personalised swim caps that are fitted tightly against your head create a smooth surface that helps lessen the drag that slows you down when you swim because it gives the water little interaction with your head while you move through the pool. Swim caps made without the seams and those that have a minimal number of wrinkles are even better at reducing friction.

Types of Swimming Caps

Swimming caps made from latex don’t allow water to permeate through them, therefore your hair stays drier. This type of swim cap also fits tightly and perfectly against your head lessening the drag which slows you down. Latex is also inexpensive but thinner and rips more easily. Lycra, on the other hand, is excellent at keeping your hair back but does not help much in reducing the drag. Silicone swimming caps are considered the sleekiest and these cost more compared to other types of caps. However, silicone caps reduce drag the most because they form the fewest wrinkles.


Your haircut is also one of the factors to consider. So, if you have a short and cropped haircut, a swim cap won’t lessen the friction enough to make a huge difference in your swimming time, unless you’re swimming competitively and every single second count. There are times when Olympians would wear two swim caps because it helps keep their swimming goggles in place and it also reduces drag more efficiently. A swimming cap closest to the body is usually made from latex as it fits seamlessly on your head and silicone is next to it.

Swimming velocity is dependent on the interaction between the propelling force and the hydrodynamic drag force. So, if you’re aiming to achieve faster or higher velocity, you should reduce the drag which resists your forward motion and help increase your propelling force. This is the main reason why swimming caps have been given more attention because of the improvements it provides swimmers. Choosing the right personalised swim caps can be detrimental to your swimming performance.

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