Channels and bottom contours
Most of a surfboard's performance is related to its bottom contours and how they blend together.
Bottom contours (when used correctly) are intended to produce controlled drag and lift. There are some basic principles and like all other areas of surfboard design, there are tried and true methods that have held the test of time as you see with many of our shapers.
Shapers configure several different designs of bottom contours. The variations are made to suit various surfing ability and different surfing conditions. The performance of a surfboard is directly related to these contour shapes, and how they blend together.
Boards usually have different bottom contours from the nose to the tail, in three sections. For example, a single concave nose, flat middle and belly tail. The precise combination of these bottom contours is dependent on how the shaper envisions the water being channelled underneath the board.
The main goal is to create a bottom contour to assist in controlled drag and lift. Some shapers get inventive, however, there are tried and tested methods of bottom contours that are reliable fall-back shapes.
The bottom of a board is directly linked to how the board will perform in the water. It is a good idea to factor into consideration how the shape can affect your level of control, how the board manoeuvres, and the level of speed.
In the interest of keeping things simple, we explain about three main categories that surfboard bottoms can fall into: flat, concave and convex.
Fhat’s pretty much the basis of it at a glance - flat is flat.
When looking in-depth, flat is fast. Shapers usually combine flat sections blended together with concave/convex bottoms, and are strategically placed to give sections of a board a “fast” area.
Combining a flat section (usually in the middle of a board), can assist in developing control, speed and acceleration. It can also help in getting the board through soft sections.
Adding a flat can be ideal for a beginner surfboard shape, because you don’t lose too much speed. However, flats don’t really have much contribution for experienced surfers wanting performance. This is because a flat shape doesn’t direct water flow, and provides no lift or leverage.
Ideal conditions for boards with flat bottoms are smaller, weaker surf.
In a nutshell, concave’s are parts of the bottom contour of the board that lift above the rail line, towards the deck. These curves ascend above the rail “into” the board. Variations and combination of single to double concave’s are what most modern shortboards are configured with.
Concave’s help in producing lift, and laminar flow (direction in which water is channeled along bottom of a board). This helps to increase the overall surface area.
Multiple concave’s placed strategically feed water under a board in such a way that the water is released through the fins and tail - behind the back foot. Fine tuning variables such as rockers, rails and fin arrangement can really customise and accentuate concave’s, and greatly affect the acceleration of a board through turns.
Concave’s are essential for surfers who are looking for speed and performance, because it adds control in higher performance surf.
Opposite to a concave bottom, a convex is any combination of flats and curves on a board that sits lower in the water than the rails.
These shapes are often referred to as a “vee” or “belly”, and are designed to help rail to rail transitions. A rider can roll from one to the other with minimal effort. It also helps with lateral stability and control, and can be very forgiving. They also act as a pivot point in the middle, which provides a higher level of responsiveness when initiating turns.
A convex bottom contour can be blended in with any portion of a board, and when combined with flats and concave’s, can create a unique and versatile performance. This bottom contour is commonly found in longboards and hybrids.
A convex bottom is ideal for fast waves, for a smoother, easier to control ride.
As with all aspects of surfboard shaping, there is no right or wrong way when it comes to bottoms, and there are endless possibilities and combinations that are constantly evolving. Some become common place while others are suited to more specific designs.
How they affect your board's rail, tail and nose is also important to understand. There are also many other types of bottom contours such as channels, panels, chines, etc. These are all functional in their own way by helping to direct water flow under the board, around the fins and give you some controlled drag depending on how the shaper intends the board to perform. We have a few of our own shapers like Phil Myers ho are renowned for their Channel bottom boards.
By understanding more about surfboard design, you can make a more informed decision about your next board.