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Fin Advice

There can be many factors to take into account when selecting the correct fins. 

To make your selection process easier we have provided the following fin terminology and some basic rules that can be used for selecting suitable fins.

Fin Terminology

The base refers to the length of the area of the part of the fin that touches the surfboard. 
The base is attributed to drive, lift and acceleration of the fin. 

Depth refers to how far the fins sticks into the water. 
Short fins will not hold as well as larger fins and may cause you to slide in certain surf. 
Conversely long fins can bog you down in certain conditions it may feel slower. 
A big fin will be 4 3/4 inches or 12 cm approx. 
A small fin will be 4 1/4 inches or 10.5 cm approx. 

Base and the Depth of the fin contribute to the overal area of a fin. 
Your fin area needs to be suited to hold the rider on the wave but be loose enough to turn with control. 

The sweep of a fins template refers to how far a fin is angled backwards. 
The further your fins are swept backwards the longer or more rounded your turns are going to be. 
A straighter fin will tend to pivot more (in FCS an example of an upright fin would be the TC Redline and a highly raked fin would be YU). 

The cant angle of the fin is how much your fin is leaning to one side. 

The toe angle refers to the angle of the fin If it is paralell to stringer of the board then there is a 0° toe angle to the board. This is set by the shaper and cannot be changed. 

Fins, similar to airoplane wings, are foiled or curved. Traditionally centre or back fins are foiled both sides but side fins are foiled on the outside and usually flat on the inside. However, there has been a trend by many fin developers to use a slight foil on many of the outside fins (ie FCS's range of fins with inside foil). 

Giving a fin foil creates areas of high pressure and low pressure. Hence, it is designed to move into the wave (hydrodynamics) to hold you in (move away from high pressure to low pressure). 


Stiffer fins provide more drive whilst a softer fin can be more forgiving.

Basic Rules

The following general rules can help in selecting fins to improve your surfing experience.

  • If your board is feeling too stiff, try using smaller fins or fins with less sweep or more flex.
  • If your board is feeling too loose and lacking drive, try a bigger set of fins, a stiffer flex fin or a fin with more sweep.
  • Generally a lighter person requires less fin area to provide enough hold on a wave.
  • To make a board more responsive, choose a fin constructed of stiffer materials.
  • Boards with a lot of rail, particularly with close fin clusters (ie guns) require less fin area (even large wave guns made for 15ft plus surf use small to medium fins).
  • Boards with a lot of rocker may require fins with greater area, more depth or sweep.
  • Boards with deep channels in the tail require less fin area (channel bottom specialist shaper Allan Byrne uses fins with particularly small tips for ease of release out of turns).
  • Boards with wider tails require more fin area than those with narrower tails (ie fishes).
  • If you are using a small board in big or powerful waves use larger or more swept fins.

Fin Materials

Fins are constructed from a range of materials and vary in their performance and costing. 

Moulded Fins 

Usually made from a composite mix of materials to give desired characteristics. Many of these fins in this category have a softer flex pattern than other construction materials. These fins make up the bulk of standard fins sold with boards at the present time. In the FCS range of fins they go under the name of Glass Flex or Composite. In the Futures range they are termed Natural Composite and Composite

Fibre Glass Fins

Layered glass fins have a solid flex pattern similar to traditional glass-on fins. Generally fins in this material have a stiff base and, depending on the template design, a varied amount of tip flex. Solid glass fins are great for fans of traditional glass-on fins who would like the convenience of a removable fin system. In the FCS range they are termed Performance Glass (PG). In the Futures range they stick to the term Fibre glass

Resin Transfer Moulded Fins

Resin transfer moulding (RTM) is a more high tech way of fin construction. It uses advanced technology that originated in the aerospace field. Often fins constructed by this method sandwich glass a layer of honeycomb foam so to reduce weight. The fantastic performance and impressive appearance of many fins in these materials make them a general favourite with the staff atFINSHOP. In the FCS range they are termed Performance Core (PC) in Futures, RTM or HEX


Why do my fins hum? 

If you have ever found your fins humming, it is due to cavitation. Cavitation occurs when low pressure bubbles in the water begin to collapse and create tiny shockwaves which are the source of the noise. 

To fix humming fins: sand the sides of the trailing edge with a medium grade sand paper. Several passes with sand paper is usually enough. 

I Have a Stripped Grub Screw! 

A very large majority of stripped grub screw problems we have encountered have been actually been a case of a bad or overused fin key. So before trying any other option try and get hold of a brand new fin key, it maximizes the chances of grabbing hold. 

Failing that, try an Alan key of slightly larger size than your regular fin key. If still no luck and no fin is in the plug, try using a small drill bit, following the same direction as the screw being careful not to damage the thread of the plug. The grub screw may exit the plug. Alternatively, get a new fin plug installed by a professional repairer. 

If you have a fin related question or, would like to request a particular item, feel free to send us an email info@scarfinifins.com.au


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