The bottom of a surfboard is where the majority of water flows. How the water flows over the bottom of the board is going to dictate how fast you go, how responsive your board will be, how much control or stability you’ll have, and how you’ll turn.
Subtle changes in the curves and shapes on the bottom of the surfboard are designed to help guide the water, and if everything goes according to plan, improve and cater to a particular type of surfboard performance element(s).
On most boards, you’re going to find a blend of different bottom shapes and contours – implemented with the overall design and purpose of the surfboard in mind.
Some bottom shapes cater to speed, some to turns, some to lift, some to surfing the rails. Just as every other aspect of the surfboard design, the possibilities are endless.
Types of Surfboard Bottoms
There’s a handful of common shapes you’ll find on the bottom of a surfboard. These include:
- Flat bottom: A flat bottom planes and glides on top of the water. It’s great for speed, but can more difficult to engage turns and maneuver.
- Belly/rounded bottom: A rounded or belly bottom sits under the water as the board moves forward. This design make rolling from rail to rail easier without sinking a rail, while sacrificing planing speed.
- Vee bottom: A Vee bottom also sits in the water and is good for turns on the rail. This can work well in big waves at speed for maintaining stability and hold.
- Concave bottom: A concave bottom features a dip or divot up towards the top of the board above where the rails sit. This helps capture the flowing water to create lift by increasing the surface area on the bottom of the board.
- Bottom channels: Channels on the bottom of a surfboard are designed to combine the effects of concave and convex (Vee/belly) bottom shapes.
Blending Bottom Contours
On any given board, you’re going to find a mix of bottom shapes and contours that blend together to influence the board’s overall performance.
Bottom shapes change and blend from the nose to the tail and sometimes out the sides.
Some common bottom contour blends you can find on a variety of boards include:
- Flat to single concave.
- Concave to belly or Vee.
- Single to double concave.
- Single to Vee.
If you look at a longboard, you may recognize a spoon concave in the nose leading to a rounder convex out through the tail. This design provides lift up from with stability and hold.
Other boards may mix flat bottoms with concaves to provide some better planing surface for paddling and then lift and drive as you’re on the wave.