Whether the windsurfing board have a concave bottom shape or channels it has almost always some type of Vee-shape along the bottom to give the board extra controllability.
Vee-shape – A compromise between speed and control
Simply put, less Vee-shape provides greater speed and less control while more Vee-shape gives more control but less speed. A perfectly flat board would give high speed but would be very difficult to control. To maintain speed despite the Vee-shape you often combines Vee-shape with a concave- or channel bottom. More about concave- and channel bottom shapes later on.
The most common Vee-shapes
Panel V means that the Vee-shape remains the same throughout the bottom
Spiral V means that Vee-shape gradually increases towards the tail