Concave

A hollowed-out curve running along the bottom. It channels water under the board, creating lift and speed.

• • Single: Pure speed.
• • Double: Speed + looser turning.

Vee

The bottom is convex (like the hull of a boat), usually near the tail. This allows the board to roll from rail to rail easily, providing control.

Channels

Grooves cut into the bottom. They direct water flow aggressively, providing immense speed and drive in clean waves, but can feel "tracky" in chop.