Hydrofoil

A hydrofoil is a lifting surface attached to a boat or other watercraft that operates underwater or near the water surface to lift the hull above the water as speed increases. The foil’s wing-like shape generates lift when water flows past it, reducing hull immersion and drag. As a result, the craft can achieve higher speeds and improved fuel efficiency. Hydrofoils may be fully submerged, supported by struts, or surface-piercing foils that interact with the water surface. Many designs use multiple foils and movable control surfaces to regulate pitch, roll and trim, often assisted by hydraulics or electronic stabilization.

Foil configurations vary. Fully submerged foils provide lift below the surface, while surface-piercing foils rise and re-enter the water to sustain lift. A typical setup uses foils on either side of the hull and control surfaces to maintain stability. Some designs employ adaptive or articulated foils to adjust lift in changing conditions. The overall aim is to keep the hull out of most of the water, minimizing drag while preserving maneuverability.

History and development: The hydrofoil concept emerged in the early 20th century with experiments by inventors such as Enrico Forlanini and, later, Alexander Graham Bell. Over the decades, the technology matured into practical high‑speed vessels, racing craft, and specialized transport. In recent years, compact hydrofoils have expanded into recreational forms such as foilboards and electric foil boards, broadening the range of users and applications.

Applications and considerations: Hydrofoils can dramatically reduce water resistance for lightweight hulls and enable high speeds. They require careful design, precise control, and robust maintenance. Performance depends on water conditions, and foils are subject to debris and impact risks. While advances continue, hydrofoils are most common in fast ferries, racing yachts, and recreational foiling systems rather than bulk shipping.