Shapes Explained - What are the most important aspects of a surfboard?

Even if two surfboards have the same dimensions in terms of width, length and volume, they can behave completely differently when surfing. The surfing behavior of a board depends on more than just the dimensions found on the bottom.

Especially when surfing on the river, for example, the number of liters on the surfboard plays a minor role compared to surfing in the sea. There usually isn't as much paddling required here, and the challenge isn't paddling into waves. Since our "Radiance" surfboards are designed for river surfing, only this will be discussed here. But you can also do a lot of surfing in the sea.

To provide a deeper understanding of surfboards, this blog article explains terms such as outline, tail, concaves and finbox placement and their influence on surfing behavior.

Outline: The external shape of the board

The tail is the crucial feature for how the surfboard behaves in turns. The most commonly used tail shape is the "squash version", but there is now a huge selection of different tails. The following explains how the different shapes affect the handling of your surfboard.

Wide tails provide more buoyancy, meaning the board is less likely to dip into the passing water. As a result, boards with wide tails generate significantly more speed due to the lower friction. The downside is that wider tails offer less grip in turns and it is generally more difficult to get the board from rail to rail. A nice compromise here could be a swallow tail, for example, in which some volume is removed through a cut despite a relatively wide tail. This means the board still remains fast, but can be better controlled in turns.

It's similar with the rest of the board - a lot of surface area offers a lot of buoyancy in standing waves and therefore more speed. As the board gets wider, it becomes harder to move it from one rail to the other.

Rocker: The “curve” of the surfboard

Nose rockers:

Flat nose rocker:

The nose rocker describes the curvature of the front part of the surfboard. If this curvature only has a small radius, we speak of a flat nose rocker. A flat nose rocker has the advantage that more of the surfboard material lies in the water when surfing, which improves buoyancy. This makes it easier to build up more speed. This speed is particularly advantageous in smaller, weaker and shallower river waves. However, the flat surfboard rocker also has a disadvantage: turns cannot be done as tightly because the radius of the surfboard (the rocker line) dictates the turns in a certain way. If this radius is large, the turn is also wider. On steep waves, a flat rocker often results in a classic nosedive.

Steeper/Lots of Nose Rocker:

Surfboards with a steep nose rocker are mainly used in steep waves to avoid a nose dive. The rockerline of the surfboard basically adapts to the shape of the wave. Speed ​​is also harder to build with a surfboard like this, but since these boards are used in powerful waves, the speed comes naturally. Turns, on the other hand, can be driven tighter than with a flat rocker because the rocker line has a smaller radius.

Steeper nose rockers are primarily used in artificial waves such as city waves and unit pools, as they offer a lot of power.

There is also a so-called nosekick, in which the last inch of the nose is directed steeply upwards to avoid nosedives.

Tail rockers:

Flat Tail Rocker:

A flat tail rocker makes it easier to build up speed because there is essentially more material on the water than a large tail rocker. That's why flat rockers are generally suitable for small, flat and weak waves. However, this speed advantage comes at the expense of tight turns.

Steep Tail Rocker:

The steep tail rocker can give the surfboard an even tighter rockerline, so that the board fits perfectly into the wave in steep waves. Together with a steep nose rocker, it enables radical and tight turns. The greater resistance of the board is balanced by the power of the waves.

Finbox position + toe in:

How the finbox is positioned on a surfboard is different for every model. Since the “face” of the wave is often very small in river surfing, only narrow turns are usually made here. To do this, the fin boxes are positioned relatively far back in the sea, similar to small wave boards. In general, you can say: Finboxes that are far back make a surfboard easier to turn, and with finboxes that are further forward you get more “flow” and can surf from rail to rail.

The toe in describes the angle at which the fin boxes are turned inwards. The larger the angle, the quieter the board will be in transitions, but it will also have more resistance in the water, making it slower. The standard toe in on river surfboards is 1/4".

Bottom concave:

The bottom concave refers to the concave (inwardly curved) shape on the bottom of a surfboard. This concave shape usually extends from the nose (front part) to the tail (back part) of the board. Here are some of the most common types of bottom concaves and their effects:

  1. Flat Bottom: A flat bottom has no discernible concave shape. It offers stability and is good for beginners. However, it may provide less control and maneuverability at higher speeds.

  2. Single Concave: This is a concave shape that extends across the entire width of the board. Single Concave increases the surface area in the water and enables faster surfing. It also offers a little more support during tight turns.
  3. Double Concave: Two concave sections extend parallel along the board. Double concave works well for waves with less power.

These different concaves are often used together. For example, in the front area of ​​the surfboard there is usually a single concave for better speed generation, and in the tail area of ​​the surfboard there is a double concave.

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