This is an important photo in this series. Let's think about the forces in this photo.
Cahill first. He's a stout guy. His boat is a new design with a high percentage of its volume near the cockpit. Drifting down that tongue combined with a few hard stokes has produced a lot of force.
The wave is primarily bouncing off the left but there is a reactionary wave on the right too. They combine to almost produce a haystack wave. Interesting thought about a haystack -- the top of the wave has only but a fraction of the force possessed by the wave!
Cahill has drifted right up the face of wave. His boat follows the curve of the wave until its horizontal force exceeds the force of a cross section of the wave; which we established diminishes going up. So, when the force on the side of Cahill's boat slices off the top of the wave, a big splash erupts.