The windsurfing board is a complex object, comprising of two important elements: the planning hull and the mast. The first element has been analyzed by computational fluid dynamics (CFD). A set of experiments was done in order to validate CFD results and to show what would be the influence of different parameters on the principal characteristics of the wave-making resistance coefficient, Cwf , and of transition point for this type of foil sections. It turned out that there is a good correlation between experimental and numerical data.
The second part deals with simulation studies carried out using finite elements method applied to an aluminum alloy mast used by sportsmen at Olympic Games Athens 2004. The aim was not only analysing its static behavior but also studying how it would vibrate in a given sea state.
The main conclusions of the present study show that:
- The windsurfing hull must be designed with a generous volume distribution to reduce wave-making resistance and to increase planning speed, at the same time maintaining enough lateral stability for safe maneuvering;
- CFD is a valid tool for predicting fluid flow around foil sections and its application can give results comparable with experiments; – A detailed experimental analysis on mast behavior, including dynamic behavior of isolated elements under different sea states, has been carried out. The structural vibrations were analysed using modal methods and appropriate parameters have been defined. These allow an estimation of fatigue life under service conditions taking into account fatigue damage due to environmental loads.
- The finite element method is a useful tool for studying mast behavior under different loading conditions and can be successfully employed to assess the dynamic response of masts in a given sea state.
Types of windsurfing boards
From the historical point of view, it might be interesting to note how windsurfing has evolved from a small boat with a sail, to the board shape we know nowadays. In fact, this evolution has been very different for planning hull and foils.
The first planning boats were made in 1970 by some enthusiasts who wanted to ride surfing waves on a sailing boat. These prototypes were made of fiberglass and had a hull similar to the present ones where the forward part is designed for planing while the rear part has more volume which provides some lateral stability. Although it’s not clear who was the first person to connect the board with hydrofoil, it’s known that in 1974 an American skipper, Peter Chila , made some tests on a board with hydrofoil from a boat manufacturer in California. In the same year, on the East Coast of USA, David Lewis tried this connection on a more sophisticated project that was never mass-produced because it was too expensive. The following hurricane season both experimented with their own boards and both realized how difficult was to control this type of boat. In 1975, the French team comprising Patrick Serin, Dominique Sudrie and Yves le Moigne created a new type of board with planing hull and hydrofoil that allowed much better control at speed. Also in 1975, Peter Chila won the world championships with a board similar to the Serin-Sudrie-Le Moigne one. These early boards can be seen as a kind of flying surfboard and had probably the first wing configuration on planing hulls.
The next significant improvement was done by Peter Chila, who designed a board with double hydrofoil and fish tail section under the rear part which was much more hydrodynamically efficient. This board was the first one that could really plane on flat water and it is considered as the precursor of modern boards.
These two types of boards, which were racing only (that means no mast), are now called extreme planing boards since they require good physical condition to control them at full speed.
ENTRY LEVEL & PROGRESSION RANGE
The entry level is the first board that a windsurf newbie will buy. It’s usually very cheap and has the minimum features needed to start having fun. The progression boards, on the other hand, offer more stability and easier handling which will allow newbies to improve their skills without too much trouble.
The construction of entry level boards is usually very simple and the materials are fragile which makes them break easily. The main feature of this kind of boards is the absence of fins, since newbies should not worry about controlling the boards at first. These boards can be recognized by their big and soft fins and the absence of a strap.
Progression boards, on the other hand, can be recognized by their fins which are smaller and more rigid than fins found on entry level boards. They also have a strap, which makes them easier to control at speed and in strong winds.
This kind of board is a type of entry or progression board that can be deflated and easily stowed in a bag, for example. These boards are lighter than their solid cousins since the material they are made from is much thinner. This fact makes them more fragile to impacts with other objects so extra care should be taken when handling them.
FREERIDE & SLALOM RANGE
Freeride boards are almost only used in flat water, having a planing hull with volume concentrated forward so the board can easily plane without too much wind. The fin is very big and rigid to allow easy carving of turns. These boards are for all type of riders since they are suitable for flat or choppy waters.
Slalom boards, on the other hand, are very thin and their fin is smaller than that found in freeride boards. They also have some extra features like more straps or fins found under the board to improve stability while carving turns. These boards work better in choppy waters since they plane easier with chop on their deck.
WAVE & FREESTYLE RANGE
Both types of boards are mainly designed for flat water but they have different features so one should not be mistaken with the other. Wave boards, for example, have a wide nose and pointed front to create lift when skimming over waves and allow surfing style maneuvers. Freestyle boards, on the other hand, have squarer noses and pointed front to make them more maneuverable. Wave boards are wider and usually stiffer than freestyle boards, allowing them to carry extra weight without sinking too much in the water. Freestyle boards are thinner and softer, making them less stable but easier to control at speed.
The windsurfing board is equipped with one or two fins that serve either to keep the rider on board or to allow speed. The size of these fins is usually measured in centimeters, but there are charts that help the users find the right fin for their boards.
FOIL FREERIDE RANGE
This kind of board is similar to freeride boards but the fin is much thicker. This feature increases its lifting power thus allowing it to plane faster, but also makes carving turns more difficult. These boards are suitable only for experienced riders since they are very tiring to control at speed.
Foil slalom boards have a thin tail and volume concentrated forward which allows them to plane easily in choppy waters. The fin is smaller than the one found on freeride boards but it’s stiffer, giving sailors better grip while carving turns.
As expected, these boards are fast. Their thinner tail makes them easier to control at speed while the volume forward helps them lift more on foil. The fin is smaller than that found in freeride boards but it is stiffer so sailors can have better grip while carving turns.
LONGBOARDS & RACEBOARDS
Longboards and raceboards are usually built using a similar mold. The difference is the fin which on a longboard is placed in a fixed position at 70-90% of the board’s length from the tail whereas on a raceboard it is moved to 40-60% from the tail. This last feature allows sailors to move their feet closer to the fin which makes it easier to control.