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 Post subject: Tech Talk: Kiteboard Design
PostPosted: Sun Aug 07, 2005 2:45 pm 
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Joined: Sat Oct 26, 2002 10:06 pm
Posts: 5274
Location: Here, Now
Here is some great info on board shapes.

General info
The boards have been divided into three different classes: directional, twin tip, and mutants. Directionals are designed to be ridden in one direction and hence have a front and a back. The twin tips are totally symmetrical and works equally well in both directions, which means that you don’t need to turn the board when you want to go in the opposite direction. A mutant can be seen as a mixture of the two previous types as they work in both directions but have one preferred direction. While the classification of the boards into directionals, twin tips, and mutants, give interesting information about their design it isn’t enough for a potential buyer. Ninety percent of the boards on the market could be classified as a twin tip even though there are huge differences between them. An alternative way to classify the boards would be to classify them according to their range of uses. Is the board designed to be used on flat water, in choppy conditions, or in breaking waves? Should it be used in strong or light wind conditions? Is it designed with beginners or pro-riders in mind? However, to cover all combinations of these variables one would need lots of different classes that would also be overlapping. It would simplify for the buyers if industry would agree on a few different classes in which the boards could be arranged. Today there are no such classes. Instead the boards are described by parameters such as length, width, weight, stiffness, outline, and rocker. For those who are familiar with the terminology and the mysteries of board design these parameters give very accurate information on how the board will feel in the water. For the rest of us it gets more or less a pure guessing game. In order to improve the odds of finding the right board we give a short introduction to how the different parameters affect the board’s behaviour on the water. Finally we exemplify how these parameters can be combined in order to create boards for specific types of usage.

Length and width
We start with the most obvious parameters, length and width. The more wet surface under the board, the earlier the board starts to plane. Beginners and heavier riders need a little bit more area than light weight, experienced riders in order to get going and be able to go upwind. To get a larger surface under the board we can obviously choose to increase either the length or the width. What we choose has a big influence on the characteristics of the board. A long and narrow board gives a smoother and more controlled ride. It is easier to get a lot of rail in the water to get upwind and the board doesn’t bounce out of the water as easy when the water is choppy. On the other hand that bounciness may be desire as it gives you a good lift when you kick the board out of the water. Such a board is often said to have a good “pop”. In short you can say that for a certain surface area, the shorter the board is the more pop it will give you, but it will also be more unsteady in the water. It can therefore be an idea to first consider the kind of conditions you will use the board in and if you first of all want a comfortable board that gives you a good grip in the water or a board with more pop. From that you can get an idea of what could be a good length of your board. If you primarily use the board in flat-water conditions and like to pull off the latest wakeboard tricks, a short board like 120 cm or even less could be good for you. If you, on the other hand, usually ride in choppy conditions and like to be able to dig down the rail and push hard in the turns without worrying of the board loosing its grip, a board of at least 130 cm could be better for you. The width is then determined by how much you weight and in how strong winds you will use the board. The heavier person and the lighter wind, the wider a board will be needed.

Rocker and outline
Ok, this far it has been quite straight forward and not that difficult. Next we will look at the influence of the outline and the rocker of the board. With outline we mean the bending of the rails of the board and with rocker we mean the bending of the bottom line. We start with the rocker.
On a directional board the bending of the bottom line is often divided into rocker and scoop, where the rocker line is the bending in the back of the
board and the scoop is the bending in the front. For a twintip board those two will be identical since the board is symmetric, and here we will not
distinguish between them. In short it can be said that the more rocker the smoother the board will behave. The rocker stops the board from digging
down into the waves, especially when the board is ridden flat, as after landings or in the transitions between one rail and the other. What you loose with a lot of rocker is mainly light-wind capabilities and pop. It isn’t only the amount of rocker that matters but also its distribution. It is common to have a relatively plane surface in the middle of the board that helps the board to start plane, while the last centimetres of the board have relatively lot of rocker so that it will turn smooth and so that the front of the board doesn’t dig down in the water. Sometimes the rocker even has a step in the far ends of the board that further prevent the nose to dig down after landings etcetera. As usual there is a downside also with putting most of the rocker in the ends of the board. In this case the problem is ones again that we loose pop. For the outline we have the same ground principles as for the rocker, that is, the more curve the smoother ride but once again to the prise of less pop and ability to plane. It is often in the interplay between the rocker and the outline that the secrets of a well working board lies. How well this work is of course very hard to tell by less that trying the board. The common recommendation is lots of curve in the board if you want to have good control in the turns, especially if you want to ride waves, and less curve if you like to jump and do tricks.

Flex
If we add length, width, outline and rocker we get a rather complicated formula. To complicate things further we add the flex of the board. A board with lots of flex “eats up” the bumps in the water. Instead of bouncing when the board hits a bump, the board bends which make it easier to maintain the edge in the water. The result is a smoother ride when the water is choppy. The flex also make it possible to use less rocker since the rocker increases when pressure is applied. This can be practical since this way you can have a board that starts to plane early and in the same time turns well and maintains the grip in the water when you push it hard. The downside is that the board can loose speed when you land hard after a jump, as it then tends to bend a lot. A board with too much flex can also give a spongy feeling.

Other things
Apart from the parameters above, there are lots of other parameters that we have chosen to not treat in detail as weight, volume, fin placement, and bindings. The common recommendation is that the lighter the board the better, but a certain weight can be needed to stop the board from flying away during board-off tricks. The volume is more or less insignificant once you are powered up and riding, but it helps to get the board to plane and to maintain the speed when the power in the kite disappears. This is mainly of interest when you are riding waves and want to ride without having a lot of power in the kite. If we look at the fin placement a classic design with four small fins, one in each corner of the board seems to work well in most cases. If you want extra grip in the water you can have one or two additional fins on the heal side of the board. As for the bindings, normal foot straps are recommended, as they are easy to get into and provide sufficient support.

- Copied from Kiteforum.com, submitted by GODman.

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 Post subject:
PostPosted: Tue Aug 09, 2005 12:50 pm 
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Joined: Wed Nov 27, 2002 4:38 pm
Posts: 1142
Location: 44.9286, -93.60828
Here is another great link for board design:

http://members.home.nl/f.nijhuis/kitesurf/allabout.html


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 Post subject:
PostPosted: Wed Jul 26, 2006 2:51 pm 
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Joined: Mon Mar 21, 2005 9:58 am
Posts: 124
Location: Cedar Rapids, IA
Here are a few other links that have pictures of steps for building a board:

From EH Kiteboards, detailed picture view of laminating and vacuum bagging:
http://www.cabareteairforce.com/news/14 ... 08-02.html

Pictures showing one method for adding PVC/ABS rails:
http://freespace.virgin.net/cav.labs/


Kiteboard terminology explained (similar to Tighe's info)
http://freespace.virgin.net/cav.labs/

Some design considerations from Dereck Camacho; food for thought:
http://www.dereck.com/dckiteboards/design.htm

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 Post subject:
PostPosted: Mon Aug 28, 2006 8:36 am 
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Joined: Mon Mar 21, 2005 9:58 am
Posts: 124
Location: Cedar Rapids, IA
Source for inexpensive fins:

http://www.omnitech-engineering.com/fins/default.asp

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