FAQ

With America's Cup and SailGP choosing T-foils, the question is why Flyte uses Z-foils and why this fits our target sailors better. T-foils are excellent at the pro's level. Our choice is deliberate: practicality, performance, simplicity.

practicality:

• Z-foils can be easily removed: lifted out from the top, no wires, no mechanics.
• T-foils stick out on the sides: need more care near a pier, legs may touch the wing when pushing the trolley, and they can complicate docking alongside.
• T-foils and flipping: harder to flip the boat on land for quick maintenance, as you do e.g. with an A-Cat (mast hook troubleshooting or trapeze maintenance).
• Z-foils are self leveling: there is automatically less lift the higher the boat flies, due to the shape of the Z-foils. The self leveling works within a speed range, as the lift increases with boat speed. While it is no problem to foil with fixed rake settings adjusted for top speeds, additional rake adjustments increase performance and assist in adapting to sailing mode.
• T-foils require continuous adjustments: either mechanically through a wand system like on the Moth or with mechatronics and rake control like the F50.

performance:

• Canting: T-foils like in SailGP F50 gain upwind performance by canting to generate lateral lift; Moths heel windward for a similar effect. Z-foils are angled already, so no separate cant system is needed for some lateral component, though active cant lets T-foils tune that force.
• Righting moment: If both foils stay in the water, a Z-foil generates reduced lift on the windward side, helping preserve righting moment. A T-foil lifts on both sides unless you retract or actively control the windward one, which can reduce righting moment. Its span outboard of the hull can add some lever when immersed. Flyte’s Z-foil is placed further outboard than on a typical A-Cat to recover some lever without the extra control system.
• Drag: both Z-foils and T-foils cause drag if not lifted out of the water on the windward side. Leaving them down is a trade-off favoring practicality and simplicity against top speed.
• Z-foil rake adjustments: active rake adjustment for Z-foils is primarily to optimize performance toward the sailing mode, like minimizing drag when floating to take speed, maximizing lift for earlier take off, reducing lift when speed is picking up to keep the nose down and create top speed at an optimal lift/drag ratio, while reducing risk of popping out or ventilating.

simplicity:

• No parts inside: Flyte Z-foils have no moving parts inside, also no wands required.
• Weight, space, power: the T-foil system we would consider requires additional actuators to adjust rake and cant on the foils, as well as a lifting system for the windward foil. That adds weight, is potentially bulky, increases power consumption and technical complexity. We intentionally avoided this for now (target audience) but keep it open as a possible future upgrade path.