Hyrdofoils are another technology that is transforming wind and water sports. Basically the hydro foil acts like an underwater wing to lift the hull or main body of the sailboat, surfboard, kiteboard etc.. out of the water. The foil therefore provides lift as well as lateral resistance similar to a keel or centreboard. But the real benefit is speed.
Foils operate a minimum speed that when activated lift the body of the craft up and out of the water. This leaves only a small streamlined foil in the water and the craft can reach very high speeds. It eliminates much of the water's drag and the effect of the waves as the vessel rides above the water and waves.
Traditional Monohull boats displace water and have alot of resistance. They go fast only when they are "planing" - akin to skipping along the surface of the water. Boat designs have improved to allow better planing in lower speeds but there is only so much that can be done. As well planing of monohulls is greatly influenced by the amount of small waves or "chop" on the surface of the water. High performance monohulls (like the Tiwal) are very wide and flat to allow for quick and easy planing.
Windsurfers or SailBoards as they are known to many, were often considered among the fastest wind driven water craft as they were basically wide, flat and ultra light with massive sails using the sailor as the balast. Kiteboards also acted like windsurfers and were vary easy to plane.
Catamarans (such as the Mini-CAT) were generally faster than traditional monohulls because when they were heeled, only one of the hulls were in the water. Lateral resistance was provided via either a centreboard in each hull or of the hull itself was designed like a blade. The weight of the flying hull also provided balast to help the boat sail in higher winds. Tri-Marans also operated on principles similar to the CAT's.
And for many years the battle for the fastest was often waged between windsurfers, kiteboarders and Catamaran's. And then began the era of the foil.
Hydro foils provide a smooth, high speed sailing experience free of much of the noise and banging of CAT's and boards.
The moth is an example of a high performance Hydro Foil Dinghy Sailboat. The moth has a complicated history which you can read about HERE. But now adays people generally think of the moth as a foil sail boat.
From the videos you may notice this is a total wet sailing experience and is really on sail at high speed when the foil lifts the boat out of the water. Another difference is that the sail is leaned towards the wind rather than away from it like in a traditional boat.
They're not cheap, being made of mostly Carbon fibre and other materials. They are not easy to sail and can't be beach landed. They're not "stable and safe" for novices, kids or taking the family sailing. This is an extreme sailboat so it's probably not a sail boat for most people but it sure looks like a fun thing to try...
Maybe we will try and get a rental or demo unit one day. But for now it's pretty it's obvious we are biased. We think the Tiwal and mini-CAT are the best choices for most sailors offering high performance in an ultra-light, ultra-portable package that's suitable for a wide range of skills and sailors and a wide variety of conditions.
But that is the beauty of sail boats, there is room for many different types, styles and kinds all providing a different perspective of the same experience.