What Is a Hydrofoil (or Foil)?

A hydrofoil is a specially shaped underwater wing designed to generate lift as it moves through water. Just like the airfoil of an aircraft wing produces lift from airflow, a hydrofoil produces lift from water flow. In simple terms: a hydrofoil is a wing operating under the water surface. When a vessel equipped with hydrofoils increases its speed, the shape of the hydrofoil causes increasingly more lift force. This force is generated by a pressure difference: The lower hydrofoil surface has a higher pressure than the surrounding water, and the upper surface has a lower pressure.

At the take-off speed, the lift force becomes strong enough to raise the hull out of the water. Once lifted, the boat experiences dramatically less drag because the hull is no longer pushing through the water: the vessel is foilborne and flies over the waves.

Why Use Hydrofoils?

Hydrofoil vessels provide several key advantages over conventional hull designs:

1. Huge Increase in Energy Efficiency:
   By lifting the hull clear of the water and reducing drag, hydrofoil boats achieve significantly better fuel efficiency, especially at higher speeds. Less resistance means the vessel requires less power to maintain the same speed.
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2. Smoother Riding Experience:
   Because the hydrofoils operate below the surface, they are much less affected by waves than a traditional hull. As a result, hydrofoil vessels deliver a noticeably smoother and more stable ride, improving passenger comfort and payload conditions even in choppy seas.
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3. Enables Green Propulsion
   The low resistance that Hydrofoils have, enable them to sail fast with only a little bit of energy. This makes battery- or hydrogen-powered boats much more affordable and sustainable.
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4. Low wave and wake generation
   Hydrofoils barely disturb the water surface, so there is less visible wake behind the boat. Also, almost no waves are formed, saving the environment from wave erosion and slamming.
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5. Higher range and speed
   Because hydrofoils require much less power at high speed, vessels can achieve higher top speeds with the same motor power and enjoy significantly greater range from each battery charge or fuel tank.

So, hydrofoils combine advanced hydrodynamic design with practical performance benefits. By acting as underwater wings, they reduce drag, increase efficiency, and offer a more comfortable experience on the water. This makes hydrofoils an increasingly attractive choice for modern marine applications.

At Flying Fish, we develop hydrofoil systems that enable all these benefits. As a reliable technology partner for boat builders, we make sure the boat meets the desired performance.

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