Trying To Understand Windsurfing Fins - Confused??   With boards and sails offering more range of use than ever, the fin is often something that is overlooked yet it is one of the most vital ingredients to achieve perfect performance synergy. However there is often a great deal of confusion about how and why a fin has such a bearing on bringing everything together, hence why I have put together some notes, hopefully in layman's terms. So to start off with just think of a fin like a set of tyres on a car - using rubber intended for the speed track will not normally suit an off-road environment, and vice versa. If you match the fin specifically to the board style you are riding, the prevailing water surface conditions and also the amount of engine power, you will be amazed by the performance transformation. Most good modern boards are supplied with a fin optimised for the mid-range of power input and average water conditions for what the design was intended - so adding an extra fin or two into your quiver can be really beneficial increasing not only your performance achievements but also extending the possible range of use from each piece of equipment.   Fin Quality - Buying Cheap = False Economy   Any good fin manufacturer spends a great deal of time developing and testing their products. Satisfaction for the end user doesn't stop there, as one of the most important considerations is the quality of production – a good fin design built badly can be awful. We mainly choose to supply fins from Select because they have invested a great amount of time and money into their production technology ensuring that the products we deliver to you are the closest to those top performance final prototypes. Most non-custom brands use Polyester, Vinyl ester, or G10 glass materials. The fins are normally either machined by hand or produced using CNC milling equipment before finally being hand finished. Often these production methods result in fins with tolerances that deviate too far from what was intended by the designer. Additionally the rather static mechanical properties of the stated materials can only ever result in fins that are unable to adapt to the variable loadings placed upon them. Select in contrast use high tech moulding equipment to ensure that their fins are 100% consistent. Importantly by using a range of Pre Preg materials it is possible to precisely position the design components to achieve the correct amount of flex and twist without having to compromise the all important actual physical fin profile.   Fin Choice - Getting It Right!   There are many ranges to choose from and often the process of selection is fairly obvious, but for some applications it is the subtleties in size and style make the difference that result in the ‘magic combinations’ being achieved. Our fin product pages provide detailed information about what each fin is intended for in addition to guidance about specific board and sail size compatibility. However often this is not a precise science as too many variables are involved. Hopefully the notes that follow offer what most readers will find to be a non-technical insight into how a variety of design factors influence the performance a fin is likely to deliver. If having read this information you still require some specific guidance then please feel free to get in contact with us.   Outline Shape & Length   The straighter a fin is the more lift it will generate size for size when powered, but that characteristic also restricts the degree of manoeuvrability. A curved fin might not generate as much lift but it will turn much more readily. A longer fin will generate extra lift! Think of how the long-straight wings on a glider are designed to allow the aircraft to soar without any engine power, whereas a fighter jet that has extreme power on tap has very raked wings allowing it to rein supreme in the agility stakes.   Rake Angle   Fins when loaded will try and find an upright or balanced position in the water - therefore a raked fin will normally trim a board more nose high whereas a fin that is almost upright will trim the board lower to the water. A fin with a variable rake is better suited to a board with a curvy rocker line as that is less sensitive to the riding position on the water. A flatter rockered (race/slalom/speed) board that has been designed to run off a minimal wetted area requires a more specifically matched fin.   Fin Head Fittings   Here are the six most commonly utilised fin box systems currently being fitted by the board manufacturers. To some people this number of variations seems rather crazy and in some instances I'd agree! However there are pros and cons of each and when getting into the necessities in terms of actual strength, engineering weight, ease of use etc etc it becomes more obvious why each type exist! Always check the box type carefully before purchasing fins for your board! Power A simple single bolt system that is quick & easy to fit and great for most applications. Tuttle A two bolt system often found in racing boards. Very stiff, strong and securely fixed. Deep Tuttle A deep version of the Tuttle design. Offers more lateral strength for highly loaded applications. A standard depth Tuttle fin fits in a deep box - use 15-20mm longer bolts. US A shallow box fitting often found in boards that have thin tails that cannot be engineered to run a bolt-thru design. Most US boxes have some positioning adjustability making them ideal for wave boards where riders often like to tune the performance by moving the fin. Mini Tuttle This is a relatively new design that is found in multi-fin boards. Lightweight to engineer and also straightforward to use with the quick to fit single bolt retention. Trim Found on the current Bic OD shapes in addition to many older Bic and Fanatic boards.     Profile & Width   A design with a thicker profile generates more power/lift but that also causes drag. So a fin optimised for early planing will often have a pronounced profile for maximum lift, which being used in lighter winds doesn't cause too many drag issues, as the speeds achieved are often lower anyway. A fin optimised for higher speeds has a much thinner profile; these require better technique to get going and remain on track but when up to speed they are the most efficient. Increasing the chord (width) of a fin will assist in how easily it will stay on track, especially in chop, but that again compromises the ultimate performance in terms of drag.   Flex & Twist   The amount of flex in a fin has a direct bearing on how the board will track across the water surface. A stiff fin is like having rock hard race car suspension - sure that is often the ultimate for transmitting maximum drive but it is only possible on very smooth surfaces where control is not an issue. In choppy/rougher waters the ability a fin has to flex is vital as the dampening effect that has on the power output allows the board to travel across the water with some degree of consistency. Think of how a 4x4 vehicle with soft suspension can drive across a rough surface without shaking to pieces - sure ultimately it may not be so fast but at least it will get to the destination in one piece. Some fins also have an element of twist engineered into them in the tip area. A fin that can twist is better able to respond to sudden loading variations, like as an example when changing direction in an extreme move. But a fin that twists excessively can cause a loss of drive, increases drag and often cavitates (spins out / loss of grip) so it is important that this characteristic is optimised correctly.   Fin Lift   The amount of lift a fin delivers depends upon the factors already covered. Excessive or insufficient lift can have some notable consequences as listed below.  Consideration should also be given to the general compatibility of your equipment, how it is all set-up, and the suitability of such for the prevailing conditions. Often sailors blame performance shortcomings on the fin when it could be something as basic as poor harness line tuning that is causing a major problem... Excessive lift often causes: Control problems. Poor manoeuvrability. Reduced speed potential. Bad rider techniques.   Insufficient lift can cause: Early planing issues. Lack of upwind ability. Spin-outs when going fast. Board feeling dull & slow.