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How I built my own kite surfing bar





Disclaimer: Everything I describe has been done specifically tailored to my needs. That includes but is not limited to my weight, my style, and my preferences. I also never unhook and usually ride my waveboard. Big air or wakestyle is none of my concern. It is obligatory that you adapt my plans should you intend to build your own kite bar. The following is not recommended for anyone nor do I take any responsibility or liability for anything resulting from this write-up.


Motivation

I used a North and Cabrinha bar before I got into this. While both worked fine, I did like the stiff lines from the Cabrinha bar but hated the rubber tubing. The Cabrinha bar weighed in at about 1.5 kg, while the North bar was slightly above 1 kg. But weight was not my main concern. I really liked how easy to ride the North felt in comparison to the Cabrinha bar. So something had to be done. Simply using the North bar exclusively wouldn't work since it is five line bar. Also the "V" in my kites differs.

Process

My Cabrinha bar size is 48-56 cm and I was able to comfortably ride anything from 7 m² to 17 m² with it. So I figured 50 cm might be a good compromise. After all, my biggest kite currently is a 14 m².

You can get a carbon tube (and just that) for about 12 Euro on eBay with a diameter of 20 mm (exterior) and 18 mm interior). It is not solid but hollow. I needed to drill quite a big center hole (diameter: 10 mm) to accommodate the lines. To strengthen the bar I decided to fill the middle part (about 10 cm) with epoxy. Once that was done I also filled the ends so that some air was inside the bar and would keep it afloat. Should I build another bar I would buy a bigger bar (e.g. with 25 mm diameter and 2 mm wall thickness). However, the one I used seems to be stable.

Grinding the carbon and the epoxy to get the shape I liked was tough, but water cooling while grinding helped to mitigate the heat. A final layer of epoxy on top made sure it is as smooth as it could be.



I wanted to keep it simple so I decided to use a Single Frontline Safety (SFS) instead of a fifth line. This meant to choose between several systems.



A1: Loop to loop connection. While A1 is commonly used I did not like the idea of having constant tension on a plastic stopper ball. Also, the powerlines are not identical in length, making it harder to get them exactly correct. It would also bear the risk of the safety line getting stuck with whatever part.

A2: Loop to ring to loop. Uses a ring instead of a direct connection. This somewhat helps, but still poses some risk.

A3: Designated safety line attached to powerline. This is probably a mixture of fifth line and a four line kite. Being its own line, the safety will have no trouble slipping through anything in case of use. I chose this system.

I attached the safety to the power line using a brummel lock splice to create a "Y".



There won’t be any tension on the safety line most of the time, so the connection is not under any stress and should be stable. Also, the safety line is only 0.1 mm thicker than the powerline so it should fit in nicely. Impressively enough this diameter increase raises the breaking load by 33%, hence making it a viable alternative as a safety line. You may even choose to use it as your power lines if you want more safety (see below).

Choosing lines

Common line types include the Liros DC xx0 and Liros DC xx1 series. The former use SK75 Dyneema, while the latter use SK99 Dyneema. SK99 has less stretch, is thinner and should give a more direct steering on the kite. The price difference with 23m lines was less than 20 Euro in total. The weight difference is about 50 g with the xx1 weighing in at a little less than 150 g for 23m lines.

I was able to get a table illustrating some key features of the lines.



Testing suggests that steering lines (back lines) shouldn’t get more than 25 kg of load each. The powerlines (both of them) shouldn’t get more that 100 kg of load. It is very advisable to have a big margin of error with these values.

The DC000-0201 and DC000-0301 as steering and power lines respectively seemed to give a reasonable margin of error (factor 8 for the steering lines and factor 6 for the power lines). Two lines of DC000-0301 would mean a force of about 600kg to get it to break. This means even weakening the line with a Palstek (reduces breaking load by about 50%) would be possible without getting into trouble. However, I am glad to have this margin and would like to keep as much of it as possible. Hence, I will use brummel lock splices only and expect these to reduce the breaking load by no more than 20%.

Line cost were 0,85 Euro/m, 0,91 Euro/m, and 1,24 Euro/m for the 201, 301, and 401 respectively.

Note: It is entirely possible to step it up a notch and use the DC000-401 for all lines. E.g. if you are really heavy, do really heavy stuff or just like things to be extra safe. Be aware it is most likely going to increase the line cost substantially. This obviously depends on the price you get buying the lines. Let me know if you try it.

Overview

To get an overview of the needed lines and parts I drew a schematic overview.



It can be noted that the upper part is divided into 12 m and 11 m lines. This is not necessary and I did not actually cut lines there. However, should you want to fly different sizes of lines this is a possible split. The lines can be connected using two eye splices that are connected loop to loop.

Also, all measurements include some slack to accomodate for splicing and the occasional mishap. My plan was to get to a total length of 23 m. This scheme was used to determine the quantities of lines I needed to order.

For the depower chord I chose a sheathed 5mm Dyneema line with 1050 daN breaking load. The sheathing has the advantage of better grip to your hand, the clam cleat and a layer of protection from abrasion. I have yet to figure out why North uses a raw Dyneema line.

I chose the colors to be most intuitive and unanimous. To mark the otherwise black bar I chose a red beginning of the steering line for the left side and green for the other side. Using a bigger line (401) will have an advantage in handling and also allow for knots to adjust length (if necessary).

The blue line is my safety line. This color is not used elsewhere and hence can always be clearly identified. You don’t want to self-rescue and then be confused as to which line you should wrap up first. The powerlines are white and the steering lines black. There is no particular reasoning behind that. Those colors where available and I like them.

The quick release (QR) is best explained by the picture. The parts needed are minimal.
Not on the picture: I used another smaller stopper ball to keep the carbon bar from touching the metal of the QR. This may not be necessary, but I wanted to minimize the stress on the carbon bar. Also the splice turned out to be pretty thick. Therefore I freed it of the sheathing and fixed it just above with a whipping (conveniently hidden under the stopper ball).



Cost

The total cost of building this bar is about 200 Euro not factoring in the hours of work. This shows that building your own bar is probably not going to save you money. Buying a last year model of any big brand will get you on the water a lot quicker. However, this bar weighs around 400 g and does exactly what I want. Most likely it will have better lines too. But the real upside is that after building your own bar you can truly say you understand what is behind it and value all other bars better.

Other parts used can be found below.



Hints on splicing

The D-Splicer Fixed F10 worked great. Except for the 201 lines. Those were too tiny for the splicer. I had to use a needle and wire to get the splices done and it took forever. In hindsight I would buy the 301 also for the steering line. It is marginally thicker and way easier to splice.

Your power lines (as well as the steering lines) should have exactly the same length. With the line buried in the line, the line will get shorter. It is nearly impossible to figure out by how much after the fact. Luckily you don't need to if you mark the points where the line is spliced on both lines at the same time before(!) you splice.

If you choose to connect the safety line like I did (A3), then the power line you splice it into will get shorter. I found that inserting a piece of line of the same length on the other power line is a quick remedy.

Hints on lines

Use pig tails. They can easily be replaced and can take a knot or two, if you choose a stronger line (e.g. 4 mm).

Bury a bungee in the safety line to make sure it doesn't swing around when the kite is trimmed/depowered. I buried a 3 mm bungee in a 401 line. I do not recommend that. It just barely fits and is a lot of work. Get a slimmer bungee or a bigger rope. Also secure the bungee with a whipping at both ends. I found that the maximum depower/trimming is about 20 cm. Hence your bungee should be able to stretch by that length.



Compatibility

I wanted to use this bar for both, my Cabrinha and my North kites. Hence I included a variable "V". It is as simple as it gets. A low friction block from Ronstan, splice in a dyneema and tie it to one of the lines using a stopper knot.



Line deferrer

After the first testing I quickly realized that the lines may easily (and brutally) run over and then constrain my hands. Hence I decided to bring in some line deferrer. These ended up being plastic tubes with a diameter of 6 mm. They are pointed at an angle of around 8° which seems to be a good compromise for the kite sizes I am planning to use. In addition I added some shrinking tube around the bottom 50 cm of the steering lines. This will help to prevent damage due to the line deferrer as well as make it easier to grab into the steering lines above the bar.



Testing

The bar during some early testing. The depower line is still very long and the right side of the bar is blue instead of green. There will be more and very careful testing before I take it out on the water.





It hasn't gone out on the water yet, but some tests at the beach with a 10m² kite (even unhooked), worked out well.





Thank you for the help from the members of these internet forums:
kiteforum.com
surfforum.oase.com