{"id":30714,"date":"2026-02-09T00:07:04","date_gmt":"2026-02-08T23:07:04","guid":{"rendered":"https:\/\/pumpfoilers.ch\/en\/?p=30714"},"modified":"2026-02-09T01:20:45","modified_gmt":"2026-02-09T00:20:45","slug":"high-aspect-ratio-foils-for-pumpfoiling","status":"publish","type":"post","link":"https:\/\/pumpfoilers.ch\/en\/high-aspect-ratio-foils-for-pumpfoiling\/","title":{"rendered":"High aspect ratio foils for pumpfoiling"},"content":{"rendered":"\n[et_pb_section fb_built=“1″ _builder_version=“4.16″ _module_preset=“default“ width=“100%“ custom_margin=“0px||||false|false“ custom_padding=“0px||||false|false“ global_colors_info=“{}“][et_pb_row _builder_version=“4.16″ _module_preset=“default“ global_colors_info=“{}“][et_pb_column type=“4_4″ _builder_version=“4.16″ _module_preset=“default“ global_colors_info=“{}“][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“]

Recently I was asked why pumpfoil wings are actually so wide. When starting sideways from a dock or float, a foil with a large span can sometimes be tricky. Especially if you have no way to position the wing tips underneath the dock or float, a big and confident jump is required when pushing off sideways \u2014 something that can feel a bit intimidating for beginners.<\/span><\/p>\n

To get to the root cuase why many manufacturers produce wings with a larger span \u2014 so\u2011called high\u2011aspect\u2011ratio foils \u2014 we need to take a short detour into fluid dynamics.<\/span><\/p>[\/et_pb_text][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“]

Lift- and propulsion force<\/h2>\n

First and foremost, the front wing\u2019s job is to generate lift (see also: Physics of a Hydrofoil<\/a>). Lift is a function of the foils\u2019s shape and the speed at which it moves through the water. In pumpfoiling, the rider must provide the propulsion respectively the necessary speed. The force acting against that forward motion is the drag produced by the foil moving through the water.<\/p>[\/et_pb_text][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2026\/02\/Drag-and-Propulsion-Force.png“ title_text=“Drag and Propulsion Force“ align=“center“ _builder_version=“4.27.5″ _module_preset=“default“ width=“53%“ width_tablet=“53%“ width_phone=“53%“ width_last_edited=“on|tablet“ global_colors_info=“{}“][\/et_pb_image][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ hover_enabled=“0″ sticky_enabled=“0″]

Figure 1: Propulsion- and dragforce<\/em><\/p>[\/et_pb_text][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“]

That means that the more drag a foil produces, the more energy the pumpfoiler has to put into the system while pumping. Conversely, the less drag a foil has, the less force the rider needs \u2014 allowing for longer pumping distances. But what does this have to do with the aspect ratio?<\/p>\n

Aspect ratio<\/h2>\n

The aspect ratio is the ratio between a wings\u2019s span and its chord length. The wingspan is the distance between the outer wing tips. The chord length is the distance between the leading and trailing edge of the wing. The aspect ratio is calculated by dividing the square of the wingspan by the reference wing area (see also: Dimensions of a hydrofoil<\/a>).<\/p>[\/et_pb_text][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2022\/10\/Formula-Aspect-Ratio.png“ alt=“Formula Aspect Ratio“ title_text=“Formula Aspect Ratio“ align=“center“ _builder_version=“4.27.5″ _module_preset=“default“ width=“29%“ width_tablet=“34%“ width_phone=“34%“ width_last_edited=“on|desktop“ global_colors_info=“{}“][\/et_pb_image][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“]

However, the aspect ratio is not just a number \u2014 it has a direct influence on the drag, more precisely on the induced drag of the foil. What we can state is that the ratio of lift to drag increases as the aspect ratio becomes larger. The reason for this lies in the wingtip vortices that form at the edges of the wing.<\/p>[\/et_pb_text][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“]

Wingtip Vortices<\/h2>\n

Wingtip vortices form primarily at the ends of the wing due to the large pressure differences between the upper and lower surfaces. This pressure difference causes a lateral flow of air, which then rolls up into spiraling, counter\u2011rotating vortices.<\/p>[\/et_pb_text][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2026\/02\/Vortex-Low-and-High-Aspect-Ratio-Foil-scaled.png“ title_text=“Vortex Low and High Aspect Ratio Foil“ _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“][\/et_pb_image][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ hover_enabled=“0″ sticky_enabled=“0″]

Figure 2: Vortex<\/em><\/p>[\/et_pb_text][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“]

Wings with a high aspect ratio have the advantage that the wing tips have less surface area, which reduces the vortex\u2011induced downwash \u2014 and therefore significantly lowers induced drag.<\/span><\/p>\n

As mentioned earlier, the primary task of the wing is to generate lift. The amount of lift produced depends on the wing\u2019s speed, the density of the water, the wing\u2019s surface area, and the lift coefficient. The lift coefficient itself depends on the wing\u2019s shape and therefore varies between different wing designs.<\/span><\/p>\n

 <\/p>[\/et_pb_text][et_pb_image src=“https:\/\/pumpfoilers.ch\/en\/wp-content\/uploads\/sites\/2\/2022\/04\/FormulaLiftForce.jpg“ alt=“Equation Lift Force“ title_text=“FormulaLiftForce“ align=“center“ _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“][\/et_pb_image][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“]

If we simplify the model and treat speed, water density, and the lift coefficient as constant, then lift depends only on the wing\u2019s surface area. This required area can be achieved through different wing shapes \u2014 either with a relatively narrow wingspan and a longer chord length, or with a larger wingspan and a shorter chord length, meaning a higher aspect ratio.<\/p>\n

Conclusion<\/h2>\n

To reduce the induced drag caused by wingtip vortices, designers create wings with shorter chord lengths. As a consequence, the wings need a larger span to achieve the surface area required for generating lift.<\/p>[\/et_pb_text][et_pb_text _builder_version=“4.27.5″ _module_preset=“default“ global_colors_info=“{}“]

However, reduced induced drag is only one component. Wings with different aspect ratios come with different advantages and disadvantages. High\u2011aspect\u2011ratio wings are characterized, among other things, by the following features:<\/span><\/p>\n