When you are new to foiling, or want to progress, it can be difficult to know which foil to choose. Low Aspect, Mid Aspect, High Aspect : what are the differences? Which foil should you choose according to your level and practice? We explain everything in detail.
The Foil has revolutionised board sports. It allows to fly over the swell, to move from one wave to another, partially or totally out of the water. It is accessible to all sizes, all levels, all conditions… Whether it is with a wing board, kite board, surf board, SUP… Here are all the criteria to take into account when deciding between a Low Aspect or High Aspect fin.
The Foil works like an underwater plane by generating hydrodynamic lift through the speed it acquires. Consisting of a mast, a fuselage, a front and rear fin (the stabiliser), the foil allows the rider to glide through the water. The fins are arranged parallel to the board, and can be controlled simply by foot pressure. The front fin has a curved shape at the top and a flatter shape at the bottom, which creates lift. The width of the fin, measured from the centre of the leading edge to the centre of the trailing edge, is called the “chord“. The length of the fin, measured from one end to the other, is called the “span“, the same principle as in aeronautics.
Before choosing between a high aspect ratio or a low aspect ratio foil, it is important to understand what an aspect ratio is. The aspect ratio of a foil is a mathematical ratio that describes the shape of the wing. It is the ratio of the wingspan (the distance between the two tips) to the chord (the distance between the leading edge and the trailing edge).
The higher the aspect ratio, the greater the span of the wing in relation to its chord. This means that the wing is longer and narrower. Conversely, a low aspect ratio indicates a shorter and wider wing.
There are 3 categories of aspect ratio for a foil:
There are two calculations for calculating the aspect ratio of a front foil:
Here are some key points to consider when choosing between a low aspect ratio foil and a high aspect ratio foil :
A low aspect ratio foil will be more manoeuvrable, ideal if you want to make tight turns but still have great control. The chord offers stability in the longitudinal axis. The aspect ratio is a limiting factor for manoeuvrability. The higher the aspect ratio of a wing, the less manoeuvrable it will be.
The weight of the fin has no influence on the overall performance of the foil, but we can give you a few pointers to help you understand.
Firstly, the weight of the fin is determined by the amount of material you put into the wing. If the wing is foamed, then the weight will be less.
However, a high aspect ratio fin does not necessarily have to be very thick. Therefore, it will be made of carbon (depending on the thickness), so it will be a bit heavier than a foam wing. Low aspect and thin wings, on the other hand, require a lot of rigidity and will therefore be heavier because they are made of 100% carbon. Conversely, a wing with a moderate aspect ratio, but thick, will be foamed. However, as the wing is larger, it will be just as heavy.
Low aspect ratio foils are more suitable for beginner foilers as they offer better stability. However, they do not offer much room for improvement. That’s why at Sroka we have decided to design foils with a moderate aspect ratio which offer ease of learning, forgiveness but also excellent glide so that your foil can evolve.
The choice of kite depends on what you want to do. To glide on swell trains, a high aspect ratio kite will be more efficient. Indeed, in most cases, foils with a higher aspect ratio generate more glide and allow you to fly longer without having to use the wing. However, with the same surface area, profile and thickness, they will not go faster than a medium aspect.
If you are looking for control and manoeuvrability at high speed, a wing with moderate aspect ratio is more interesting. This is the case if you want to start freestyling for example.
At Sroka, our philosophy is to create products that perfectly suit your needs, while remaining versatile, rather than forcing you to adapt to the equipment. We are always open to comments and feedback on the Sroka sessions Facebook group, as we design these foils primarily for you and to share our passion.
If you still have any questions about this, or any other request, please do not hesitate to contact us !
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