Ezzy Hydra

Ezzy Sails have released a dedicated foiling sail with a unique design; we get the lowdown from designer David Ezzy

- David Ezzy

 WS: The Hydra is one of the most radical looking windsurf sails in the world, can you tell us more about the sail’s innovative design? 

DE: To understand my reasoning behind this weird looking foiling sail, we need to consider the unique requirements foiling places on a sail.

1 - Must be efficient. This allows you to use a smaller sail.  Since the foil rides above the water, the Hydra foot is taking advantage of “free” space. The foot on the Hydra forms an end-plate with the board. The end-plate stops the flow from going under the foot, much the same way winglets do on a jet. Aerodynamic theory tells us that an end plate doubles the effective aspect ratio, which is what makes the Hydra more efficient.

2 - Must be less sensitive to gusts. Every movement you make with the sail transfers directly to the foil. Sheet in, you go up, sheet out and you go down. Having a sail that does not react so quickly to gusts means you will be more stable on the foil. We know that longer boom sails are less reactive than shorter boom sails. We also know that longer boom sails tend to feel more draft back than shorter boom sails. Extending the foot as I have done, gives the sail the stability of a longer boom sail, but still with the draft forward feel of a shorter boom sail.