The channel depth is pretty consistent at about 3/8 but where the actual “FLEX step” sits, it goes deeper depending on how deep I need to go to feather it into the back section. I believe this is about the norm on all deep channeled boards to help guide the water flow, you need to break the water into two directions forcing the water to hold in a resistant manner causing forward drive. However, when the water cascades over these channels at a slower rate of speed, it causes air bubbles and creates lift, much like when you take your hand and swish it quickly under 2” of water.
The “FLEX step” is placed right between the surfer’s feet, this is done to increase the torque on the rail and give the board more/less tail rocker as speed and inertia along with the steepness of the wave cause the reaction to happen. It really helps in hollow surf, gives the board a lot of bite but still has great release as it snaps back into position. Think of Ben Aipa and Larry Bertleman in the 70’s, the stingers had a flex step….
FIREBALL channels: We actually saw these first from WAY back in the day when you look up Phil Myers, he is an Australian bloke from the 70’s he had some great ideas. Using concepts from the Stinger era, Ben Aipa’s step bottom design that was so popular in the 70’s I feel (and from research thus far) that the new chamfered channel design (where I actually do NOT blend the channel into the bottom) creates a “textured” surface as the water drives across the bottom. Much like the new speedboat designs like Gorilla Hulls design. They use textures paint “ Furthermore, we have found that the textured finish of the hull improves high speed performance by providing an air cushion between the hull and the water (similar to running on a light chop)” When in lack luster conditions, the water causes a cushion of air to be created right between your feet giving your board that extra lift needed to carry you through to the next section that has some energy. That’s about it, the outline is a tried and true swallow tail, I did and do make adjustments when I find out if the customer is a from footed surfer, if you ride off your front foot I would move the hips up 1/2” – 1” to help you drive.