2 Broken Kite Lines - 1 session?

[njrider]

Hey Starsky, EDT is sending me a bunch of short 1 foot line lengths that he sleeved on both ends. This is going to help immensely! I'm also going to replace my ratchet with a hydraulic car jack - should be smoother as it increases force.

[Starsky]

Seriously not trying to anger you, but your trying to use a weight scale as a strain gauge on a material that has almost no stretch. The point at which load rises and peaks in the sample will be really sharp when using length as the variable especially in a really short sample. Unless your using a strain device that has a memory to log peak values it will be difficult to get any accuracy. To get more accurate numbers from your set up you would need to use really long samples that can give a little stretch and afford the scale some time to register it before failure. Since you already have a digital scale, why not use it the way it was designed? Suspend it and use weight as your variable and you will approach the breaking strain at a rate the scale can report accurately. Safer too if you only ratchet the load up a couple inches and suitable for testing short samples of line. Start with a substantial weight and add sand or water slowly until the sample fails. For accuracy film the digital scale to record the final reading and avoid bounce by adding weight smoothly.

[edt]

everyone wanna be some kind of scientist but nobody wanna do no damn boring ass experiments themselves

[Starsky]

Dude, He's the one with the suspect lines!

Just pointing out limitations to the set up as presented in the video. There is no video of readings or anything. It could be easily improved with no additional special equipment.

[eree]

happens to the best of the best:
viewtopic.php?f=1&t=2374010

turned out the stupid prosaic negligence in splicing line manufacturing pieces into the spools...

and i don't think the breaking load is growing gradually slowly in the real life during wind gusts, loops or crashes

[Starsky]

Seriously? Eree, WTF!

The breaking strength of the line doesn't change, fast or slow, its measuring it accurately that is the issue.

The room for measurement error in that rig as tested is massive. If you really really really want to use that set up, you could improve your measurement accuracy by either testing it on full length lines to allow for some stretch to attenuate the loading phase long enough to get a decent reading, or have a means of adding load in a very slow progressive manner. IE gear down your ratchet so it moves only in teeeny tiny ity bitty little increments.

You can try and do that..... or recognize that your using a digital WEIGH scale and just use it to measure how much WEIGHT it takes to break the line.

[eree]

S, your positiveness is highly contagious as usual.
with all my usual negativity i hope that every heavily overpriced piece of kiteboarding equipment rated for example 600lb will hold not 100lb, not 200lb, not even 600lb, but at least 700lb. even if after outreaching 600lb the piece of gear has to be replaced...
i don't care if the scale on video has bigger margin of error than certified dynamo-meter of some major tech university.
lines should not break easily under the normal load, quickly or with the delay.
the Flysurfer lines problems with the reliability were kept in secret first, than eventually were made public and basically confirmed by the one of most expensive brands in the industry.
OP did right informing about crappy lines, may be a bit over-dramatic, but still right.
we kiters as a consumers have a right to know about cheating brands claiming high quality gear components and services. faulty lines are the worst publicity and the brands and/or retailers problems, not the members of this forum

[Starsky]

How much strain do you think a WINCH can produce? Let me give you a hint.

It's sole design objective is to produce massive mechanical advantage!

Kite line is candy floss to a winch! Both line samples in the video show that clearly, because...... its a WINCH! Dude clearly states its capable of pulling about two tonnes.

By the way, a weigh scale is not a strain gauge. It's sole design objective is not to measure and store peak strain..... its to measure weight in static conditions.

I bet an undamaged section of either line would reach its rated load when measured properly.

As to being positive. Let's put it this way. If you cant fathom my argument I am absolutely POSITIVE all the other garbage you spout about kite design is complete nonsense. Cause this is basic shit compared to kite design.

[njrider]

I think this helps explain what I'm up against....

http://www.wetestkites.com/2015/07/01/c ... strengths/

[Tone]

I do think this is interesting.

I have friends that go through bars and lines like no bodies business, and I just don't get it.

Being a relative fat ass, and the conditions I want to kite, I always go for Slingshot 800lb lines. Two of those should cover me for situations. Back lines are less important for weight, I think.

I DO hear of Naish lines breaking as much as North lines.

Maybe because there are more Naish and North riders in my area, who knows. What I do know is that the quality of lines is not up to par in general. You only have to ready the T&C on kiteboarding stuff to realise that we shouldn't be jumping high on this stuff. We should have lines that go through the same QA as paragliding equipment.

I am really keen to see more of these tests but I want to see them done with a larks head on both ends and not through clams and shit.

Well done and keep up the good (interesting) work.