How Exactly Does a Hydrofoil Board Work? A Quick Explainer

The first time we saw a hydrofoil board, we were confident that there was a deal with the devil happening. Come on, a whole human body on a board supported by that little airplane on a stick? Apparently, it works because of science, not magic. Who’d have thought? Read on for a quick explainer of how exactly hydrofoil boards work!

Hydrofoil Design

Underneath the board, there’s a long mast attached to what looks like a small airplane. This little device features wings like a real airplane—with a leading edge and a trailing edge. The leading edge is longer than the trailing edge, and that’s important to the science of this device! How? Well, we’ll try to explain it.

Science!

The title of this article implies that we know how exactly hydrofoil boards work, but that’s not entirely true. Scientists have a few ideas, but each theory has a contradiction or two, so we’ll do our best to explain those ideas, and you can draw your own conclusions!

Remember those leading and trailing edges we mentioned? The basic theory is that water passes over the leading edge and under the trailing edge, arriving at the back of the wing simultaneously. However, because the leading edge is longer, the water going over that edge moves more quickly. That produces lift and pulls the board up out of the water!

Science Is Wrong?!

Sounds simple, right? Unfortunately, it isn’t. Even though, theoretically, the water gets to the back of the wing at the same time, that’s not how it works in practice. The water going below the wing takes longer to reach the back, reducing the credibility of this theory.

The current agreement on how hydrofoil boards (kitefoils, wingfoils, windsurf foils) and airplane wings work is that, as long as more fluid (be it air or water) gets pushed downward than upward, the device will lift in the fluid.

Now that you have this quick explainer and know how exactly hydrofoil boards work, we hope it’s clear that it involves very little black magic. Next time you find yourself on a hydrofoil, remember—you now understand as much as scientists do, which is to say, not entirely.