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Ezzy Hydra Foiling Sail

Ezzy

  • $744.95




David Ezzy fell in love with hydrofoiling, so he made the Hydra. Foiling open’s a new challenge for sail design because the fundamentals of foiling are different than in normal windsurfing. This is why the Hydra looks so different than a normal windsurfing sail.
The first big difference between foiling and normal windsurfing is that the foil flies through the water with much less drag, causing the angle of the apparent wind (the wind created by your movement plus the real wind) to shift more forward, which means that the wind angles are completely different than in normal windsurfing. Second, you need a powerful sail to pump up onto the foil, but once you’re on the foil, you want a very easy-to-control, light sail. And the third difference is that you are above the surface of the water when you’re flying on the foil.
The biggest visual difference between the Hydra and a normal sail is the elongated foot. This is very similar to how winglets work on a jet wing, and aerodynamic theory tells us that an end-plate like this greatly improves the efficiency of the sail. For example, David can ride a 4.0 in conditions he would normally ride a 6.0. A long foot like this only works because the Hydra flies above the surface of the water.
The extra long foot provides the needed low-end power to get up on the foil without using cambers or an extra batten below the boom, saving close to a kilo in weight. Being able to ride a smaller, lightweight sail makes foiling more fun by giving you the sensation of flying with nothing in your hands. You want a sail that “goes away.”
The extra long foot also makes the sail more stable. This means that you are less vulnerable to gusts throwing you off balance when you’re flying on the foil, making foiling a lot easier. But at the same time, because only the foot is extended and not the entire sail, the pull of the sail remains forward for a more comfortable sailing experience.
The Hydra also borrows the 3/4 batten concept from our hardcore wave sail, the Taka. A 3/4 batten allows the sail to luff, which means that it can easily go from full to flat. This is important for many aspects of foiling. This helps the Hydra to be extra powerful when you’re pumping it but flat and responsive when flying on the foil. And, the Hydra’s 3/4 batten is the reason it can de-power so easily and change its shape for the needs of the foil. When you sail up wind, you want a flat sail, and when you sail downwind, you want a full sail. The 3/4 batten allows both to occur without having to adjust the outhaul.
David had 5 goals when designing the Hydra:
1) Must be more efficient than a normal sail
2) Must be less sensitive to gusts than a normal sail
3) Must have early power to get up and going but also controllable when flying
4) Must be able to de-power easily
5) Must be super light weight
WHAT IS DIFFERENT? FOILING V.S. NORMAL WINDSURFING

First off, because the foil can fly through the water with so little drag, the wind angles are different, which means that the apparent wind (the wind created by your movement) shifts forward. Second, you need a powerful sail to pump up onto the foil, but once you’re on the foil, you want a very easy to control, light sail. And third, your board is above the surface of the water when you’re flying on the foil.


EXTENDED FOOT BATTEN

The elongated foot on the Hydra takes advantage of the board’s height off the water to create a hyper efficient sail. On a normal windsurfing sail, a long foot like this would hit the water when cruising and simply not work, but when foiling, we can take advantage of this “free” space created by flying above the water. The extra long foot forms an end-plate with the board. This is very similar to how winglets work on a jet wing, and aerodynamic theory tells us that an end-plate like this greatly improves the efficiency of the sail. For example, David can ride a 4.0 in conditions he would normally ride a 6.5.

The extra long foot provides the needed low-end power to get up on the foil without using cambers or an extra batten below the boom, saving close to a kilo in weight. Being able to ride a smaller, lightweight sail makes foiling more fun by giving you the sensation of flying with nothing in your hands. You want a sail that “goes away.”

The extra long foot also makes the sail more stable. This means that you are less vulnerable to gusts throwing you off balance when you’re flying on the foil, which makes foiling a lot easier. But at the same time, because only the foot is extended and not the entire sail, the pull of the sail remains forward for a more comfortable sailing experience.


3/4 BATTEN

The Hydra also borrows the 3/4 batten concept from our hardcore wave sail, the Taka. A 3/4 batten allows the sail to luff, which means that it can easily go from full to flat. This is important for many aspects of foiling. This helps the Hydra to be extra powerful when you’re pumping it but flat and responsive when flying on the foil. And, the Hydra’s 3/4 batten is the reason it can de-power so easily and change its shape for the needs of the foil. When you sail up wind, you want a flat sail, and when you sail downwind, you want a full sail. The 3/4 batten allows both to occur without having to adjust the outhaul.

HYDRA SAIL SPECS

Ezzy Hydra Luff Luff Boom Boom Ezzy Mast Base Weight
Size (sq.m.) Min Max Min Max Extension Kg
4.0 353 358 131 141 340/340 14-18 cm NA
5.0 395 400 151 164 370/400 10-16 cm NA
5.5 413 418 158 172 400/400 14-18 cm NA
6.0 434 439 166 179 400/430 20-24 cm NA
7.0 TBA TBA TBA TBA TBA TBA NA

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