Mal etwas zur Verständigung, von Select Fins:
THE SCIENCE OF WINDSURFING FINS
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Since you love windsurfing as much as us we thought you might appreciate some insight and theory into fin dynamics.
There's a lot of hype and jargon spoken about fins, so we hope you find this theoretical information useful when making choices about what fins to buy.
There's a lot to cover, so we're going to send this to you in a series of short episodes, starting with a common misconception …
THINNER PROFILES ARE FASTER
Indeed thinner profiles are faster - BUT only when used for speed sailing at very high speeds. For 'normal' speeds, thinner profiles in most constructions simply don't deliver enough LIFT.
There are a lot of influences on generating lift:
… and more, that all play their part.
Any one fin that's built without taking into account fine tuning of all of the above for specific purpose is selling you short in control, speed and lift.
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Both the profile form and profile ratio are normally optimized for the use and intended speed range. At higher speeds thinner profiles normally show a higher efficiency. Hence thinner profiles are better suited at higher speeds - but not necessarily for reaching them.
A higher % profile will, in principle, generate more lift compared to a lower % profile at a given speed - but with a higher resistance.
For speed, the amount of lift generated should be high, while the resistance must be as low as possible.
Profile efficiency (lift ÷ drag ratio) has a relation to the required speed range and type of profile. Profile forms and outlines are a real scientific area. E.g., the realms of NASA, Boeing, Airbus, Shipbuilders etc. who, for as long as aerodynamics has existed, have spent infinite amounts of money to find 'the ideal profile'.
There's a cut-off point at around 9% (of chord ÷ thickness). Below 9% would typically be used for speed. 9% or higher for slalom use.
It could be a good idea to develop fins with >12% ratios specifically for very low speeds, like first time use etc . The result will be a high-lift fin at very low speed. Ideal to learn windsurfing on …
The amount of lift generated by a fin depends on a number of variables.
After all that science you're probably ready to go windsurfing! Next time we'll be slightly less technical BUT, the theory you just learned will help you understand the next step!
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