Slalomfinne G10 vs. Carbon. Gibt es einen Geschwindigkeitsunterschied?

Quote from Erik Loots

Increasing speed, on the other hand, always results in more pressure.

Du sprichst im ersten Absatz von lateraler Querkraft und nennst sie force oder pressure. In diesem Sinn verstehe ich den zitierten Satz am Ende des ersten Absatzes nicht bzw kann ihm nicht zustimmen.

Sobald man einmal echt schnell unterwegs ist, hält auch eine relativ kleine Finne sehr gut, das ist klar.

Höherer Speed kann doch auch mit gleicher oder kleinerer Querkraft einhergehen - etwa wenn man abfällt, auffiert oder das Outhaul dichter zieht, oder? Ev sogar auch per besserem stance.

Quote from Erik Loots

The greater the lateral force or pressure on a fin, the more a carbon fin outperforms G10. At absolute top speed, however, the pressure is not extreme since sailing is done on a downwind course. Upwind sailing demands the most pressure from the fin, which makes sense because you are sailing against the wind (wind pushes much more lateral/sideways on fin). Heavier or stronger windsurfers generate higher peak loads on the fin. Wind strength also affects fin pressure, counterintuitively, stronger wind often means less pressure on the fin. With more wind a smaller fin can be used, provided water conditions remain the same. Increasing speed, on the other hand, always results in more pressure.

Every material (high-end carbon, standard carbon, G10, etc.) has a range of pressure where deformation remains controlled and performance stays optimal. Once the pressure exceeds that range, deformation becomes excessive and the fin loses efficiency. Within a certain range, a well-designed G10 fin can be just as fast as carbon. Upwind sailing requires significant pressure, especially in light wind, where high-quality carbon fins show a clear advantage.

A practical trick with G10 is to avoid making the fin too thin—greater thickness allows it to handle more pressure. Creating an identical fin in both carbon and G10 would be pointless: a G10 design replicated in carbon would likely be far too stiff, while a carbon design replicated in G10 would be too soft, deforming quickly and becoming inefficient.

I use both G10 and carbon fins, and when properly designed, either material can deliver excellent performance. I have the same experience as Totti: for most windsurfers, a light-wind fin (often longer than 40 cm) generally feels better in carbon. For medium- to high-wind fins, however, the difference between G10 and carbon is far less (or not) noticeable. In fact, some sailors even prefer G10 in strong winds, since certain carbon fins can feel quite demanding to ride.

Display More

Lieber Eric,

ganz vielen herzlichen Dank für deine tollen sehr informativen Posts und dass du dein Wissen hier mit uns teilst.

Ich habe sehr viel von dir gelernt.

Viele Grüße

Patrick

Quote from Erik Loots

Upwind sailing demands the most pressure from the fin, which makes sense because you are sailing against the wind (wind pushes much more lateral/sideways on fin).

In diesem Satz könnte man pressure mMn mit "horizontalem Lift" gleichsetzen. Ist das so gemeint?

Ach Männer, Erik arbeitet bei der Optimierung seines Posts im Englischen mit einer KI. Hat er letztens erst gesagt. Ihr müsst euch an die KI wenden und kleine Abweichungen einfach selbst austauschen.

Erik Loots sagte, er verwende Englisch, weil er da selbst sicherstellen kann, dass das Vorgeschlagene letzlich auch das von ihm Gemeinte und hier Geschriebene ist.

Quote from dominik49

Quote from Erik Loots

Increasing speed, on the other hand, always results in more pressure.

Du sprichst im ersten Absatz von lateraler Querkraft und nennst sie force oder pressure. In diesem Sinn verstehe ich den zitierten Satz am Ende des ersten Absatzes nicht bzw kann ihm nicht zustimmen.

Sobald man einmal echt schnell unterwegs ist, hält auch eine relativ kleine Finne sehr gut, das ist klar.

Höherer Speed kann doch auch mit gleicher oder kleinerer Querkraft einhergehen - etwa wenn man abfällt, auffiert oder das Outhaul dichter zieht, oder? Ev sogar auch per besserem stance.

Display More

Hi Dominik, apologies for the language, it’s not always easy to express these details precisely in words. Especially since we all use words a tiny bit different. In my previous post (and in this one), I am referring specifically to the lateral horizontal force acting on the fin, essentially the pressure applied by the backfoot through the rails of the board horizontal onto the fin.

At higher speeds, smaller fins can be used because they generate more horizontal lift per square centimeter. Speedsurfers often rely on smaller fins and seek out a opportunity (often a gust) to break through the first (for example) 30 knots. But before they reach that speed (30 knots) the gear is not working well at all. However once that threshold is reached, the smaller fin becomes effective, enabling greater speed with improved control.

Higher speed does not automatically translate into greater lateral or horizontal pressure. This depends strongly on the sailing course (upwind vs. downwind) and the balance between wind strength and board speed.

If all other factors remain constant—for example, sailing 110 degrees downwind with equal wind strength—then increasing speed does indeed require more lateral/backfoot pressure on the fin. This is what I meant in the end of the first paragraph. In practice, though, higher speed often coincides with stronger wind and/or a more downwind course, which changes the dynamics intro higher speed with the same or even reduced lateral/horizontal pressure.

When I only apply more pressure with my back foot, the board responds by turning upwind, which increases drag and reduces speed. At higher speeds I generally try to prevent a significant rise in lateral pressure on the fin, unless something else happens.

For example, when sailing on a choppy lake and then entering a flatwater section, the smoother surface reduces drag and allows the board to accelerate. With the same downwind angle and constant windstrength, this acceleration increases the pressure on the fin. If that backfoot/fin pressure is released, the board will begin to turn further downwind and often accelerate fast. Somewhere between crosswind and deep downwind lies the most efficient course, and achieving maximum speed is largely about learning where that angle is (and how much to push/release backfoot pressure). In light wind, the highest speed is often reached closer to crosswind (a lot of pressure), when going too deep downwind will result in going slower again. In stronger wind, however, the fastest angle tends to shift more toward downwind (much less pressure)—provided the water conditions allow it.

zur segelmechanik unabhängig vom finnenmaterial geht's dann weiter hier

Da sollte man mMn noch mehr abspalten und die Threads in einer neuen Rubrik zB "Physik beim Windsurfen" zusammenfassen ( Totti-Amun )

Hat ja schon lange nichts mehr mit Carbon vs G10 zu tun.

Vielen Dank!

Quote from Basti_HH

zur segelmechanik unabhängig vom finnenmaterial geht's dann weiter hier

Danke dir Basti_HH . ggfls. kannst du noch ein paar Beiträge mehr rüberschieben. M.E nach #87.

Jetzt wieder Carbon / G10
Meine Beobachtung mit den unterschiedlichen Materialien und der daraus resultierenden Profile sowie dem Verhalten ist, dass die G10 Varianten im für diese optimalen Bereich, das ist für mich z.B. die Weedspeed von Tribal, wirklich schnell sind und obenrum gut bis sehr gut laufen. Bis dahin sind aber die Carbonvarianten z.B. die Konkurrenz von Hurricane im Vorteil...

Quote from blinki-bill

kannst du noch ein paar Beiträge mehr rüberschieben. M.E nach #87

jo. hatte ich in der tat auch schon markiert und bin dann wohl overpowered und out of control mit zuviel querkraft auf dem maus-heck in den spinout geraten

Quote from Erik Loots

In fact, some sailors even prefer G10 in strong winds, since certain carbon fins can feel quite demanding to ride.

Wie stellt sich das "feel quite demanding to ride" dar?

Quote from dominik49

Quote from Erik Loots

In fact, some sailors even prefer G10 in strong winds, since certain carbon fins can feel quite demanding to ride.

Wie stellt sich das "feel quite demanding to ride" dar?

Disclaimer: Not all carbon fins are more demanding to ride. For example, my Tribal and Sonntag carbon fins are actually easy (that is why I use these). Except my Sonntag SL-Pro 38cm and 45cm (my lightwind fins). However, many PWA competition carbon fins generate (much) more vertical lift when additional power is applied to the fin compared to any G10 fin. “Demanding” in this context means that rider input (whether applying more or less pressure on the fin) has a greater impact on the overall balance of the board and sail. As wind strength increases, and if the sail is not eased, a competition carbon fin tends to push the board much more out of the water. With several of these fins I’ve had to bend my back leg significantly and press the board extreme down to counteract the vertical lift; if that wasn’t enough, I had to open the sail slightly to reduce power and vertical lift of the fin. This results in loss of control and is more demanding for me.

When vertical lift from a fin is less sensitive to the amount of horizontal force from the sail acting on the fin, the ride becomes much less demanding. With G10 fins this is often the case naturally due to the material properties. In highwind efficiency is not key for me, keeping in balance full power (without being overpowered because the fin is lifting too much out of the water) is in my opinion more important. This is, i believe, also the reason why some windsurfers prefer G10 in highwind.

In (PWA) competition you can certainly achieve higher speeds with carbon, provided you can control it. We see in medium/low wind only carbon fins on the podium. Yet even at that level, you often see highly trained, strong, and talented windsurfers reaching their limits.

Take, for example, the PWA race photo below: the rider on the yellow board is experiencing (slightly) too much vertical lift. To keep the board on the water, he (like most windsurfers instinctively do) bends his legs and arms. This movement causes the sail to open (in contrast to the rider behind with the grey sail) and shifts his weight from the mast foot toward the rear of the board, reducing power onto the fin, pushing the board down. The photo may be somewhat misleading (as it might be just one moment), but the principle is: if the rider with the grey sail can keep applying pressure without opening the sail, he will overtake and be faster than the rider on the yellow board. Excessive vertical lift prevents further acceleration or higher speeds. A less lifty fin (G10) could have been faster for this windsurfer on yellow board (again could be, as this is just a moment captured on photo while knowing no further details about this). A different carbon fin (different twist/flex, or shorter) could also have been better/faster at that moment on the picture. If the rider on the yellow board were to switch to gear with less vertical lift, he could have continue pushing and achieve higher speeds while maintaining control.

Quote from Erik Loots

As wind strength increases, and if the sail is not eased, a competition carbon fin tends to push the board much more out of the water. With several of these fins I’ve had to bend my back leg significantly and press the board extreme down to counteract the vertical lift; if that wasn’t enough, I had to open the sail slightly to reduce power and vertical lift of the fin. This results in loss of control and is more demanding for me.

Thank you very much for the description.

I am referring to the situation mentioned as cited above. Was the fin just too big and/or soft? - or necessary in such a size in the low end wind conditions or for acceleration?

Es schaut so aus, als ob es kein Video von der Situation laut Foto von Lohan Jules gäbe. Nur die Finali von Slalom X in Fuerte 2025 gibt es auf YT.

Allerdings schaut die Heckwelle bzw sein Fahrwasser so aus, als ob er vor dem - wellenbedingten? - Abheben noch gut Wasserkontakt hatte.

Ein Grund, dass Carbon Finnen anspruchsvoller zu fahren sein können, liegt im oft dünneren Profil, dass auch leichter mal die Strömung abreissen lässt. Gerade wenn es im Chop+Chaoswelle mal wieder wilder läuft.

Quote from dominik49

Quote from Erik Loots

As wind strength increases, and if the sail is not eased, a competition carbon fin tends to push the board much more out of the water. With several of these fins I’ve had to bend my back leg significantly and press the board extreme down to counteract the vertical lift; if that wasn’t enough, I had to open the sail slightly to reduce power and vertical lift of the fin. This results in loss of control and is more demanding for me.

Thank you very much for the description.

I am referring to the situation mentioned as cited above. Was the fin just too big and/or soft? - or necessary in such a size in the low end wind conditions or for acceleration?

Es schaut so aus, als ob es kein Video von der Situation laut Foto von Lohan Jules gäbe. Nur die Finali von Slalom X in Fuerte 2025 gibt es auf YT.

Allerdings schaut die Heckwelle bzw sein Fahrwasser so aus, als ob er vor dem - wellenbedingten? - Abheben noch gut Wasserkontakt hatte.

Ein Grund, dass Carbon Finnen anspruchsvoller zu fahren sein können, liegt im oft dünneren Profil, dass auch leichter mal die Strömung abreissen lässt. Gerade wenn es im Chop+Chaoswelle mal wieder wilder läuft.

Display More

A long time ago, during my speedsurfing days, I mostly used medium to small fins (for getting the best speed in gusts). Excessive vertical lift was often the result of too much flex (too soft for the given conditions) combined with very limited twist. These fins were highly efficient and fast, up until the point where the power became overwhelming. A lot of times, I could keep control by bearing further downwind, which not only prevented too much power on the fin but also allowed me to gain even more speed. However if I underestimated a gust I had too use my muscles and release quickly power and try to keep it together.

Nowadays my windsurfing is focused on freeracing with a touch of slalom. I tend to use longer fins than I did in the past, and they are also slightly stiffer. For example, with my Sonntag SL Pro 38 cm I find that in stronger winds the fin feels a bit too long for my 73 cm wide board. The same goes for the Sonntag SL Pro 45 cm, which is oversized in high wind for my 83 cm board. With both the 38 and 45 cm fins I need to be more cautious as the wind picks up.

In lighter winds, however, these fins (precisely because they are a little oversized and very powerfull carbon fins) give me quicker planing, very fast upwind and a higher (average) speed. They also make lightwind sessions more enjoyable, since I like being able to let the board rail and fly. In medium up to highwind I use "easy" carbon or G10 fins. My smaller and medium Sonntag sl-weed, sl-pro and tribal mk2 are all what I would call a recreational carbon lay-up (easy and fun). Especially with Sonntag Fins it is possible to ask for a certain behaviour.