Positioning: Riding Higher or Lower
Let’s compare how deep each of these surfboard rails are engaged in the water, according to the shape of the wave.
The “Low surfer” trims at the bottom and his rail is only slightly sunk in the water as the wave’s shape is quite soft here.
The “High surfer” focuses on riding higher on the face, where the wave is steep. Because of the wave’s shape towards the top, his board is more engaged, so more water gets channelled under his board, helping him accelerate more.
Watch at 4:28
If you imagine how both of these surfboards sink in the wave and disrupt the water flow, they would be very different from one another. The surfboard riding high on the wave has more engagement, therefore it gets more acceleration from the water getting channelled towards the tail.