Carbon foil: Criteria to consider before buying
When choosing a new foil, one is often drawn to 100% carbon foils because all the brands suggest they are the very best. However, the reality is not so clear-cut. What criteria should be considered before buying a carbon foil?
In this article, we're going to tell you what you're not told about carbon foils to help you make the right choice.
"If a carbon foil is sold for twice the price of an aluminum foil without any performance gain, there is no point" Bruno Sroka.
A carbon foil should offer more performance, more rigidity, more glide, more finesse in flight, less drag, and more responsiveness; otherwise, you might as well stick with an aluminum foil.
What is a carbon foil?
It's a common misconception that a 100% carbon foil is always more efficient, stiffer, or faster than one with an aluminum base (mast and fuselage), but this is false. To be efficient, a mast needs to be thin and extremely rigid, which is contradictory; the thinner a mast is, the more susceptible it is to flexing and twisting. It's easy to make a carbon mast as rigid as an aluminum one if it's thick, but with production costs often twice as high, you end up paying twice as much for the same performance, which is unnecessary.
The challenge in developing a high-performance mast lies in using the best carbon fiber with the optimal layup to create a mast that is both thin and ultra-rigid. Indeed, a stiff mast is the most important factor for a high-performance foil. The stiffness of a mast reinforces the entire foil (the mast acts as a connecting arm between the board and the foil's lifting surface). The stiffer the mast, the more responsive the foil, resulting in more precise control and reaction. Therefore, stiffness is fundamental. For more information on the differences between 100% carbon and aluminum foils , check out our article on the subject. In short, a high-performance carbon foil requires a thin, rigid mast.
The quality of carbon fibers
The quality of the carbon fibers used for the mast is essential. There are three main types of carbon: basic, mid-range, and high modulus (also called high modulus or HM). The latter offers increased stiffness, reduced elongation, and superior responsiveness, making it a preferred choice for high-performance foils. However, high modulus masts can cost two to three times more than those made of basic carbon. For example, in our carbon foil, we use M40J, a high modulus carbon used in Formula 1 and aerospace. It provides stiffness in bending with minimal elongation but is significantly more expensive.
Mast profile
The thickness and chord of the mast are extremely important in determining its stiffness and drag. A thin mast (around 14 mm) will have significantly less drag than a thick mast (over 16 mm). It will glide more smoothly and allow you to reach higher speeds thanks to its ultra-thin profile, while offering better responsiveness due to its stiffness. The Sroka carbon mast is available in 14 mm and 16 mm thicknesses to suit your preferences and needs. The 14 mm Elite mast will be very thin and stiff. The 16 mm mast will be less smooth but lighter, and slightly less stiff but less expensive.
How to make a rigid carbon mast? Our choice
Building a carbon mast is a highly technical process. But here's how to obtain a rigid carbon mast.
To have a stiff mast, there are only two solutions:
- Either we increase its thickness and its cord to stiffen the whole thing and consequently we can foam the inside and be light.
This is the simplest and least expensive solution, but it greatly increases the drag of the mast and therefore the mast is slower.
- Either we increase the quality of the carbon fibers used in the mast (high modulus fibers) and increase the quantity of material, thus minimizing the mast thickness and chord length. This results in reduced drag, improved glide and speed, while maintaining a highly responsive and efficient foil.
At Sroka, we have therefore chosen the second option. Offering you one of the best carbon masts on the market, combining low thickness, thin string and unparalleled rigidity.
The fuselage
There are two possibilities for making a fuselage:
- either we keep an aluminum fuselage which will be heavier and will require dismantling the foil after each session to avoid oxidation between the aluminum and the stainless steel (the screws).
- One option is to make the fuselage out of carbon fiber to avoid oxidation and reduce weight. However, it will be more fragile and therefore more susceptible to damage. Therefore, extra care will be required. The final option is to make a titanium/carbon fiber fuselage.
At Sroka, we have chosen the carbon fiber option for a 100% carbon foil and to reduce the price of the foil, we also offer an Aluminium fuselage.
The fuselage length determines the foil's maneuverability; a longer fuselage provides greater longitudinal stability but less maneuverability. Conversely, a very short fuselage increases maneuverability and the ability to pump easily, at the expense of longitudinal stability.
However, if the mast is thin with a short chord, its maneuverability increases, making it more agile. This allows for a longer fuselage while maintaining the same maneuverability as with a less maneuverable mast that requires a shorter fuselage.
We refer you to the video alongside which explains all the differences.
The front fin
The performance of a foil front wing depends on various characteristics, such as its wingspan, chord length, thickness, twist, and the airfoil profile used. This is defined by the aspect ratio, which is the relationship between the wing's wingspan and its chord length. For example, the higher the aspect ratio, the larger the wing is relative to its chord. It is therefore more elongated and narrower.
- Low aspect ratio: These are foils with a long chord and a very short wingspan. They are great for beginners, however, they will quickly reach their speed limits due to their large chord.
- Medium aspect ratio: The perfect compromise between high and low aspect ratio. These foils are accessible to all skill levels. They are perfect for beginners while offering plenty of room for progression. They correspond to the foils in our Classic range, in larger sizes, or to the Control range in our performance range.
- High Aspect Ratio: With a high aspect ratio, these foils are more technical than others. They allow for maximum finesse in flight, resulting in excellent glide and extended flight times. They belong to our High Aspect foil range.
The stabilizer
The stabilizer (stab) or rear wing, has the role of stabilizing the foil.
The larger the stabilizer, the more stable the foil will be , but this also means more drag and therefore a slower speed. Conversely, a smaller stabilizer will provide less overall stability but offer significantly more glide due to reduced drag, potentially allowing you to go faster.
At Sroka we offer 3 types of stabilizers ,
- The 300cm2, the most stable stabilizer in our range, perfect for beginner riders or those with large front wings.
- The 240cc, the medium size, is a compromise between stability and speed. Compatible with all our front fins, it will be your best friend in light wind and also for those seeking comfort and speed while sailing.
- The 180cc engine, a weapon of speed. With its ultra-slim profile, it will allow you to exceed your speed limits.
It's important to remember that using shims will allow you to fine-tune the stabilizer to your sailing style and body size. This also allows us to reduce the number of stabilizers needed, thus meeting all requirements. By increasing the lift (by adding angle under the rear screw) or decreasing the angle (i.e., increasing the thickness under the front screw), you reduce lift and therefore drag. For more information on adjusting stabilizers with angle shims, watch this video.
To conclude :
- To get the best carbon mast, you need the best carbon fiber and the best layup, with a thin profile and minimal thickness and chord. Compare them, shop around, you'll see many differences. If the information isn't clear from a brand, ask yourself why. Or ask them!
- A mast with a thinner profile and a thinner chord like the Sroka carbon mast will allow you to reach higher speeds and will offer a better response from your foil.
- The manufacturing process of the mast is very important. An ultra-light carbon mast is absolutely not a sign of quality. It will be flexible and likely foamy inside. Consequently, it will be less rigid and feel more like marshmallow underfoot.
- Choosing the right front fin is essential to adapt your equipment to your requirements and thus optimize performance.