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Windsurfing (also called boardsailing) is a sport involving travel over water on a small 2-4.7 meter board powered by wind acting on a single sail, that is connected to the board via a flexible joint. The sport is a hybrid between sailing and surfing. The sail board might be considered the most minimalistic version of the modern sailboat, with the major exception that steering is accomplished by tilting the mast and sail rather than with a rudder.
Windsurfers can travel over flat water as long as there is enough wind; they can also cut into breaking waves and perform spectacular stunts. Windsurfing is very versatile by its relation to the sailor. It can mean a peaceful relaxed pastime on the water to some people, it can be a high-stress high-adrenalin sport to others, but it can also be a lifestyle of seeking the endless limits of perfection in skills and self-expression.
Windsurfing is particularly enjoyable at wind strengths of daggerboard. However, there are special kinds of shortboards used for racing. Shortboards, also sometimes called funboards, are usually classed as less than 3m in length and are designed specifically for planing, where the board is sliding over the surface of the water, rather than cuts through displacing it. Planing yields significantly higher speeds, more maneuverability, but involves completely different techniques than the displacing mode. Most windsurfers don't even consider sailing if the wind is not enugh to plane. All shortboards should be planing with adequate sails and tuning at wind speeds of 12 knots. The aim of planing at lower winds has led to the development of wider and shorter boards, that plane at wind speeds as low as 8 knots.
The original Windsurfer board invented by Jim Drake and Hoyle Schweitzer had a body made out of polyethylene filled with PVC foam. Later, hollow glass-reinforced epoxy designs were used. Most boards produced today have an expandable polystyrene foam core reinforced with a composite sandwich shell, that can include carbon fiber, kevlar, fiberglass, epoxy, PVC, even plywood and molded plastic. Racing and wave boards are usually very light (6–7kg), and are made out of carbon sandwich. Such boards are very brittle, and plywood is sometimes used to make them more shock-resistant. Boards aimed at the beginners are heavier (8–15kg) and more robust, contain more fiberglass, or even have an indestructable molded plastic shell.
A modern windsurfing sail is made of monofilm (clear PVC film), dacron (woven polyester) and mylar. Sensitive parts are reinforced with kevlar mesh.
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 manouevrability and generally how light and easy to use the sail feels. 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 rotation in the name. RAF sails have 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 manoeuvering. Also, RAF sails are much easier to rig.
The leading edge of a sail is called the luff. The mast is in the luff tube. The rear edge is called the leech. The front bottom corner of the sail, where the mast foot protrudes, is called the the tack, and the rear corner, to which the boom is atached, is called the 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 center of effort of the sail down. In contrary, releasing the downhaul tension shifts the center 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 center 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 comfortable to use and are meant for recreational windsurfing. Racing sails, obviously, provide speed at the expence of quailities like comfort or maneuverability.
The size of the sail is measured in square metres and it can be anything from 3m2 to 6.5m2 for wave sails and from 6m2 to 12.5m2 for racing sails, with ranges for freestyle and freeride sails spanning somewhere between these extremes. There might be exceptions to these ranges, though, learning sails for children being as small as 1.7m2 and world-record speed racing sails being up to 15m2 large.
In windsurfing competitions, there are the following disciplines:
Freestyle and Wave are judged competitions, the sailor with best technique and diversity wins. Olympic Boardsailing, Formula windsurfing, Slalom and SuperX are races where many sailors compete on a course, and Speed Racing is a race where sailors compete on a straight 500m course in turns.
In Olympic Windsurfing 'one design' boards are used. All sailors use the same long boards with daggerboards and the same relatively small sails. This choice of equipment is motivated by the requirement that the board could be used in a wide range of sailing conditions, both planing and non-planing. This is especially important for its use in the Olympic Games, as the event has to take place regardless of whether there is enough wind for planing.
Currently Mistral One Design is the olympic class. It was introduced in the 1996 Summer Olympics. Before that, Lechner design was used in 1992 and 1988, and Windglider design was used for the Olympic boardsailing event in 1984 Summer Olympics.
Formula windsurfing is quite a recent development aiming to revolutionise windsurfing by making the competitions more spectacular and less dependent on high winds. Formula is a class of boards about 100 cm wide. They have fins or skegs as long as 70cm and carry sails up to 12.5m2. Contrary to the olympic class, sailors can choose boards of different models, as long as they are certified as Formula boards, and fit fins and sails of different sizes.
Large sails in combination with the 'wide-style' design allows planing in very low wind conditions. However, if these requirements are not met, the boards cannot be used and events will not take place, as non-planing sailing is very difficult with this design. Formula boards are only used on flat water.
Formula boards have excellent upwind and downwind ability, but are not very comfortable on a beam reach. This explains why the course is usually a box with longer upwind and downwind legs, or just a simple upwind-downwind loop.
Slalom is a fast funboard race in a course shaped like a figure of eight. Most of the course goes on a beam reach with floating marks that have to be jibed around. Slalom boards are small and narrow, and require high winds. Funboard class racing rules require the wind of 9-35 knots for the slalom event to take place.
This is a relatively new discipline in windsurfing competitions. It is a cross between freestyle and slalom. The competing sailors are racing on a short downwind slalom course, have to use duck jibes on all turns, and are required to perform several tricks along the way, such as jump over an obstacle, body drag or even
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