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LOWDOWN – EZZY HYDRA

18/09/2018
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Ezzy Sails have released a dedicated foiling sail with a unique design; we get the lowdown from designer David Ezzy.

Words  David Ezzy  //  Photos  Kevin Pritchard



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.

3 – Must have early power to get you up and flying. For foiling we need a sail that is very powerful to get you moving in the lightest wind, but at the same time, it has to be controllable once up on the foil. Two things help with early power. They are a forward deep draft along with a low foot/ long boom. I have found that the ¾ batten, similar to what I use on the Taka achieves a more draft forward profile than a camber inducer. For the second requirement, the super long foot batten gives a low foot and a “long boom” feel.

4 – Must be controllable when flying. You want a flatter sail once up on the foil. The water drag caused by the board is greatly reduced when flying which is what allows you to go faster than the wind speed when up on the foil. This also means the apparent wind shifts more forward, which means you must sheet in more. A flatter sail allows you to sail closer into the wind and a fuller sail allows you to sail further off the wind. For off the wind, you want a very full sail. The ¾ batten design on my foil sail allows both to occur without having to adjust the outhaul.

5 – Must be able to de-power easily. It is important to be able to de-power the sail to prevent foil-outs. The ¾ batten allows you to gently luff the sail when you sheet out, without the sail pushing back at you. This keeps you stable on the foil.

6 – Must be super light weight. The beauty of foiling is the feeling of flying. To me that means having a sail that ‘goes away” when you are up on the foil. So, the challenge is how to make a light sail that delivers power and stability. My strange looking foot design achieves a low foot with only one foot batten, which is lighter than two foot battens. The ¾ batten gives a deeper, more forward draft, while saving a lot of weight compared to a cam’d sail.

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WS: How does the Hydra feel when you are sailing it and could you use it on a normal board?
DE: The hydra is unlike any sail I have ever used, super stable and light in your hands. Yesterday I was on a 4.0, when I would otherwise have been on a 6.0 or 6.5 for regular windsurfing. The hydra feels “invisible” in your hands when sailing off the wind and it goes upwind like a much bigger sail. The Hydra definitely won’t work on a normal windsurf board, the foot would be in the water.

WS: Is the Hydra designed for using as small a sail as possible in light winds or can it be used in normal sizing and higher winds?
DE: Both. I enjoy using a smaller sail, but the Hydra can handle a lot of wind too.

WS: Foiling – fad or the future?
DE: Is foiling a fad or the future? Who cares because it is so much fun! I got into windsurfing 40 years ago, not because it was a fad, but because I loved it. Foiling is the feeling all over again, but more. I never do fads. When kiting came along, I said nope. When stand up came along, I said nope. I tried foiling for the first time last summer and after that I can’t get it out of my head. I am at the beach every day and I mean every day foiling. All you need is 7 to 8 knots and I can find that somewhere on Maui.

The Hydra is available in sizes 4.0, 5.0, 5.5, 6.0 and 7.0.

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