Currently, two designs of a sail are predominant: camber induced and RAF (Rotating Asymmetric Foil). Cambered sails have 1-5 camber inducers, plastic devices at the ends of battens which cup against the mast. They help to hold a rigid aerofoil shape in the sail, better for speed and stability, but at the cost of manoeuvrability and generally how light and easy the sail feels to use. The current trend is that only the large race sails have camber inducers. The rigidity of the sail is also determined by a number of battens.

RAF sails have battens which protrude beyond the back aspect of the mast. They have to flip to the other side of the mast when tacking or jibing, hence the name rotation. RAF sails have an aerofoil shape on the leeward side only when filled with wind. They can be absolutely flat and depowered when sheeted out. This feature is much appreciated in the freestyle and wave riding disciplines.

In comparison with cambered sails, RAF designs offer less power and stability when sailing straight, but are easier to handle when manoeuvring. Also, RAF sails are much easier to rig.

The leading edge of a sail is called the luff, whilst the rear edge is called the leech. The front bottom corner of the sail, where the mast foot protrudes, is called the tack, and the rear corner, to which the boom is attached, is called the clew. The bottom edge, between the clew and the tack, is called the foot. The mast is in the luff tube.

A windsurfing sail is tensioned at two points: at the tack (by downhaul), and at the clew (by outhaul). There is a set of pulleys for downhauling at the tack and there's a grommet at the clew. Most shape is given to the sail by a very strong downhaul, bending the mast in the luff tube. The outhaul tension is relatively weak, mostly just to keep the sail from flapping.

The sail is tuned by adjusting the downhaul and the outhaul. Generally, the sail has to be trimmed more for stronger winds. More downhaul tension loosens the upper part of the leech, "spilling" the wind at the gusts and shifting the centre of effort of the sail down. Conversely, releasing the downhaul tension shifts the centre of effort up. More outhaul makes the sail flatter, easier to control, but less powerful, and less outhaul brings more camber, more low-end power, shifts the centre of effort to the front, and limits the speed by increasing the aerodynamic resistance.

Different sails are used for various disciplines of windsurfing: wave, freestyle, freeride, race. The main features of wave sails are that they reinforced to survive the surf, and are absolutely flat when depowered to allow riding the waves like the surfers do. Freestyle sails are also flat when depowered, and have high low-end power to allow quick accelerations. Freeride sails are all-rounders that are ...

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