With the choice of your fin, you can noticeably affect the properties of the board. This is partly about the basic properties that you want to modify, such as stability and resistance. But even behavior in special conditions can be changed, such as neutral conditions in lateral wind, short turning radius for turns, or protection against seagrass. Many parameters can work together for one property but provide varying results for other properties. So both the length and the surface affect the course stability but the resistance is most affected by the length and only to a small part of the surface.

Length

• more length gives more course stability
• more length gives more general stability
• shorter length gives less resistance
• shorter length gives less risk of grounding

Surface

• more surface area gives more course stability
• more surface gives more stability
• smaller surface gives better turning radius
• smaller surface makes the board more neutral in lateral wind

Shape

• straighter shape gives more responsiveness (turns)
• backward inclined shape is better against seagrass
• backward inclined shape protects better in grounding

Width

• a thinner fin gives less resistance

Other factors

• heavier and stronger people need bigger fins
• the further ahead the fine box, the greater the fin is needed for the same traction