The barrel: a complex hydrodynamic formula | Photo: Shutterstock

Mike Stewart shared an old picture featuring personal annotations on the anatomy of a wave and the formation of the barrel in particular.

The legendary bodyboarder made it 30 years when "I thought I knew something about tube rides." The historical sketch reveals Stewart's impressions on the breaking of a wave.

Mike divides the vertical picture into two halves and draws a 90-degree angle with the horizontal axis being the horizon line, and the vertical line being the lip line.

From there, the nine-time world bodyboarding champion dissects the behavior of a wave, since it formed hundreds of miles away from the shore until it breaks near the beach.

Mike Stewart seems to analyze, dissect, and explain the creation of the barrels, and how wave riders should position to exit the blue cylinder.

"Every tube has a different average lip arc. Different arcs equate to different speeds," notes Stewart.

Waves: the theory of a barreling wave according to Mike Stewart | Sketch: Mike Stewart

The Shockwave

The Hawaiian waterman also theorizes on the impact of a falling wave lip. He calls it the "beginning of a shockwave."

"As this whitewater gets sucked up the face and the wave moves forward, a trench will form directly behind the explosion," adds the experienced bodyboarder and bodysurfer.

That is why you need to "watch for areas below the lip arc. These will impact before the rest of the lip, creating explosions and shockwaves in front of you."

Stewart's in-depth analysis of the tube also identifies two type of barrels - those with thick lips, and those with thin lips.

The simple, yet highly understandable drawing also features a gem that could only come from the mind of someone who believes theory (and "Science") and practice are key to knowledge and success.

"When this section [the lip area close to the face of the wave] folds over, it will most likely compress the chamber causing 'spit' conditions," concludes Mike Stewart in his precious drawing.

In the end, the pictorial chart is a lesson on how to get barreled, and how to avoid the impact of a breaking wave, for instance, when duck diving a bodyboard.