Overcome Your Bow Wave!

by Abbie Fish, Ritter Sport Performance
 

Everybody knows what a boat is. I’m sure most people have ridden on a boat, owned a boat, or watched one from a dock. When you were in one of these scenarios, did you noticed the massive wave hitting the front of the boat—opposing its direction?

If so, are you a swimmer and ever wondered if this wave affects you in the pool? Do you know how to “surf” on your bow wave? If not, let’s get started...

What is a bow wave?

A bow wave is formed on both sides of a moving vessel due to the forward motion of the vessel. Basically the water crashes into the front of the vessel and cannot move through it, so it changes its path of motion to around the vessel itself. This build up of extra water molecules around the vessel is what creates the wave.

Essentially, when a swimmer is swimming, the same wave is formed. The key here is that the swimmer gets in front (or better yet, on top) of their bow wave.

Think back to the boat for a second. Have you ever been on a boat when the throttle was thrusted into full gear and the top of the boat rode high, while the bottom of the boat rode really low? This is due to the fact that the speed of the boat is not exceeding the speed of the bow wave.

It wouldn’t be very fun to ride on a boat in that position for an extended period of time. But eventually, all boats will level themselves out. How? The boat’s speed exceeds the speed of the bow wave.

Cool, but what does this all have to do with swimming?

Essentially, if you get on top of your bow wave, you will significantly reduce your drag and increase your speed.

How do I know my bow wave’s speed?

There is an equation to calculate the velocity needed from your body to exceed your bow wave:

Vbody=1.248 x √H

Vbody is the speed that your body needs to produce in order to exceed the speed of your bow wave. H represents your height in meters.

I’ll use myself as an example: I’m 5, 8”, which equates to 1.72m. If I put 1.72m into the equation, my Vbody speed is 1.64 m/s. If I were to swim 50m Freestyle, I would need to complete the 50m in 30.49 seconds or less to be swimming on top of my bow wave. This is disregarding the start, turns, and underwater time.

Essentially, this means I need to be producing a very fast speed to get on top of my bow wave. Otherwise, the wave will do more harm to me than good. Most USA Swimming time standards require a swimmer’s speed to greatly exceed their bow wave speed (obviously, height dependent).

Let’s use Caeleb Dressel as another example: Caeleb is 6, 3”, which converts to 1.91m. His velocity required to overcome his bow wave is 1.72 m/s. Caeleb would need to complete a 50m Freestyle in 29.07 seconds or less.

We all know due to Caeleb’s recent swims that his speed is significantly overcoming his bow wave. In a recent race analysis I did of Caeleb’s 100-Yard Freestyle at the 2017 NCAA Championships, I computed his average velocity to be 2.21 m/s--almost ½ m faster per second than his bow wave. Caeleb is surfing on his bow wave!

What does this mean for you?

Compute your bow wave’s speed and calculate with your race times whether you are swimming on top or behind of your bow wave. A general rule of thumb is that most elite swimmers ride higher in the water (due to being on top of their bow wave), where slower swimmers ride lower.

Not sure how to ride higher?

Ask your coach how you can maximize your propulsive efforts in each stroke to generate more speed. After all, the more speed you can create coupled with a low drag coefficient, the faster you will swim and potentially, surf down the pool!

About Abbie Fish
From qualifying for Olympic Trials to interning at USA Swimming, Abbie has been on all sides of the sport. Abbie is a technical swim coach at Ritter Sports Performance and has worked with swimmers of all abilities from ages 5 to 90. She believes anyone with the heart to train can benefit from technical advice! Learn more at RitterSP.com.