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I need convincing too:) Bar back lines!

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andylc
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Re: I need convincing too:) Bar back lines!

Postby andylc » Tue Apr 24, 2018 4:33 pm

If you guys could let us know who is having handbags with who that would be lovely.

Your logic seems to make sense, although I'm not sure how much well cared for lines wear / lose their tensile strength over time? I'm unfortunately enough in full-time employment so perhaps the frequency I get out makes this less of an issue but I've never had the impression over the years that my flying lines have been obviously degrading enough to make me think they are losing a significant percentage of their tensile strength. Or maybe I just buy new stuff too often...!

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Re: I need convincing too:) Bar back lines!

Postby edt » Tue Apr 24, 2018 4:39 pm

lines get stronger with use as the dyneema molecules gets more and more aligned in the same direction, but that's why not why they weaken, they weaken because every time sand rubs against the lines, or you twist them on to the bar, or you make a turn, the lines fray and wear, that's where they get weaker. There's also a little bit of UV degradation but dyneema is pretty good against UV. Spectra of course has some mechanical stuff done to it which pre-aligns all the molecules so unlike Dyneema which gets stronger with use, Spectra always get weaker with use just from the UV. Anyway, I'm saying yeah you're right lines don't really degrade over time from using them as lines. It's all the other stuff that puts wear into lines. I don't know how it's possible to care for lines and make sure they never get fuzzed up I don't think it's possible? Maybe you can do it, I can't. Thinner lines of course wear faster so need to be replaced more often. The only exception to this is q-power which only wears right at the knot.

andylc
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Re: I need convincing too:) Bar back lines!

Postby andylc » Tue Apr 24, 2018 4:47 pm

It would be interesting to know how much normal use does weaken them over time, ie whether there is actual data out there. Or maybe I'll just find out one day as I drop screaming into the water...

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edt
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Re: I need convincing too:) Bar back lines!

Postby edt » Tue Apr 24, 2018 5:03 pm

Just use your lines and let them wear until they snap. When they look like a caterpillar they are about to snap.

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Re: I need convincing too:) Bar back lines!

Postby Ozone Kites AUS » Wed Apr 25, 2018 2:11 am

edt wrote:
Tue Apr 24, 2018 4:39 pm
lines get stronger with use as the dyneema molecules gets more and more aligned in the same direction, but that's why not why they weaken, they weaken because every time sand rubs against the lines, or you twist them on to the bar, or you make a turn, the lines fray and wear, that's where they get weaker. There's also a little bit of UV degradation but dyneema is pretty good against UV. Spectra of course has some mechanical stuff done to it which pre-aligns all the molecules so unlike Dyneema which gets stronger with use, Spectra always get weaker with use just from the UV. Anyway, I'm saying yeah you're right lines don't really degrade over time from using them as lines. It's all the other stuff that puts wear into lines. I don't know how it's possible to care for lines and make sure they never get fuzzed up I don't think it's possible? Maybe you can do it, I can't. Thinner lines of course wear faster so need to be replaced more often. The only exception to this is q-power which only wears right at the knot.
There is really very little difference between Spectra and Dyneema, both are just trade names for UHMWPE or Ultra-high-molecular-weight polyethylene, Spectra is owned by Dupont and Dyneema by DSM. I've never read anywhere that the fibre gets stronger with use. Spectra and Dyneema are hardly affected by UV, I have a set of flying lines made from Spectra that are now 20+ years old and they seem as strong as they ever were.

Have a read of this

https://en.wikipedia.org/wiki/Ultra-hig ... lyethylene

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Re: I need convincing too:) Bar back lines!

Postby Matteo V » Wed Apr 25, 2018 2:25 am

downunder wrote:
Tue Apr 24, 2018 3:37 am
You are again patronizing, however with a bit of 'toned' response, which is slightly better. But still not polite enough. It can be learned, not to worry.
In response to???
Matteo V wrote:
Mon Apr 23, 2018 3:07 pm
I am not trying to berate you because I very much appreciate your post. It adds discussion and gives kiters an idea of the mentalities/ideas out there. So thanks and keep posting.
So you see insincerity in my advice? Please understand that I am sincere, and I even tried to head off you going in this direction by mentioning the fact that I was not trying to berate you. I am also truly sorry that I have "triggered" you and absolutely do not mean to patronize you with this statement either.

And let me be candid with you –

If you ever find yourself in a frame of mind such as “everyone is against me” or “this person is out to get me”, drop the emotional side and just look at the reasoning, logic, and evidence that person or those people are presenting. Your emotions on this issue are of no help to you in finding the answer. They are actually doing the opposite and/or they allow you to be manipulated. Someone attacking you personally typically indicates a weakness in their position. I would not do that in this case as I am trying to help you understand the answer to your question. And I would admit I am wrong before I would result to such personal attacks, or even a subtle attempt to "patronize" you.


As for your additional questions -
downunder wrote:
Tue Apr 24, 2018 3:37 am
The perception of 'pulling weight' with the bar is wrong when I think of it:

- same rider, high pressure on the bar. Is he/she pulling more weight on the bar?
- same rider, light bar pressure would indicate LESS weight?! How? The rider is the same?
You gotta clear this one up for me. I am totally lost with what you are trying to say. Are you talking about different kites? Or are you talking about perception of bar pressure?

Then, if you can, pleas explain what the heck these statements mean???

downunder wrote:
Tue Apr 24, 2018 3:37 am
You Matt can at least show appropriation for this ppl coz they are pushing the boundaries in this sport. Not you I'm afraid, you just follow (apologies if not, but that's how it sounds).
and
downunder wrote:
Tue Apr 24, 2018 3:37 am
NO JUMPING means NOTHING in my books.

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Re: I need convincing too:) Bar back lines!

Postby edt » Wed Apr 25, 2018 2:31 am

In the mid-1990 s, PSR developed a patented recrystallization process for converting
Honeywell s S-900 fiber into a higher strength material. The Plasma process produced
ropes that were the highest strength constructions available, predating the availability of
ropes made from either S-1000 or SK-75. PSR s patented Plasma process involves
realigning the molecular structure of the Spectra fiber under a combination of precisely
controlled tension and elevated temperature. This procedure not only produces a stronger
fiber but also ensures that all of the individual filaments within the rope component being
processed are the same length, thereby maximizing fiber efficiency. In order to control
the process with a high degree of precision, the Plasma process is carried out on a subcomponent
of the finished rope (i.e. a strand or other twisted component) rather than the
entire rope.
One of the primary elements of the patent is the method used to heat all of the fiber
filaments uniformly. This involves complete immersion of the manufactured rope
component in a hot liquid bath. Synthetic fibers are poor conductors of heat.
Consequently, the only way to make sure that all of the filaments are heated to the same
temperature is to use a hot liquid to penetrate throughout the fiber bundle. Any other
type of heating will not produce the desired results.
Heat-Set Ropes
Since its development, Plasma has been extremely popular in a wide variety of
applications due to its durability and strength. In recent years, other rope manufacturers
have attempted to duplicate the results obtained from the Plasma process by utilizing a
heat setting technique. However, heat-set ropes are produced by running a strand or rope
under load through a forced hot air oven, not the liquid bath that is a key part of the
Plasma patent. The hot air heats up the surface of the rope but, because of the poor
thermal conductivity of synthetic fibers, the interior of the rope does not reach the same
temperature. Consequently, this type of process is only partially successful at best.
There is some increase in initial strength, but this is due primarily to the high loads used
to process the rope. This load in effect work-hardens the rope, not unlike the initial
increase in strength obtained from a new rope if it is tensioned repeatedly for several
cycles. However, the uneven heating also produces a rope with unequal fiber lengths
throughout the rope s cross-section because the interior of the rope will not be heated
sufficiently. This produces uneven load sharing throughout the rope s cross-section that
will adversely affect the rope s strength efficiency and overall performance. In
conventional double-twist braided ropes, especially in the larger sizes, there is already an
inherent imbalance between the outer yarns in the strand and those in the interior. Heat
setting of the rope can make this imbalance more pronounced. Another byproduct of this
process is a stiffening of the rope structure due to the high loads placed on the rope
combined with the hardening effects of the dry heat. It is important to note that Plasma
ropes are not heat-set and do not exhibit any of the adverse performance properties
associated with this type of procedure.

* * *

The above is from a data sheet by jeyco summarizing some of the technology used creating spectra. Dyneema is created using a completely different process and because of it the molecules are not as well aligned as spectra. The repeated resistance on Dyneema aligns the molecules and strengthens the rope. When you look at repeated testings of break loads for dyneema if you start doing the test at a lower load and then ramp up they give you a higher load than if you break it right away. At least that's what I remember.

Anyway correct me if I'm wrong, but of course, spectra and dyneema are very similar and for our uses we can consider them identical.

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Re: I need convincing too:) Bar back lines!

Postby downunder » Wed Apr 25, 2018 2:58 am

Matteo V wrote:
Tue Apr 24, 2018 3:34 pm
Really quick, and I'll address the rest of your post directed at me later:

Do you understand the concept of wear over time vs breaking strength. Specifically the example of 200kg lines worn to 50% of their original strength yield 100kg breaking strength, and 300kg lines worn to 50% of their original strength yield 150kg breaking strength?

Take that down to internal abrasion at a sleeved loop - 200kg lines worn to 20% of their original strength yield 20kg breaking strength, and 300kg lines worn to 20% of their original strength yield 30kg breaking strength.

I think I do "know" you and your are thinking "that is only a 10kg difference". But that is 1/
Hmm,

You are hard man to argue with. Ffs I am not talking about degradation, what this has to do with line strength ?

People answered and you are not accepting the fact:

- it is possible to use super thin back lines.

How thin? We don’t know simply coz we don’t know how much we pulling.

Stop hiding behind general answers we all know. We passed the point

The question is simple: how much?

Matteo V
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Re: I need convincing too:) Bar back lines!

Postby Matteo V » Wed Apr 25, 2018 3:07 am

downunder wrote:
Wed Apr 25, 2018 2:58 am
The question is simple: how much?
The answer is not much more complex - it is variable - depending on body weight, style, and if you crash the kite.


And yes, wear starts instantly when you pull the kite out for the first time. The wear curve is also variable and considers factors such as loading, care for the lines, particulate matter such as sand or suspended minerals in the water, and many other factors.

downunder wrote:
Wed Apr 25, 2018 2:58 am

Ffs I am not talking about degradation, what this has to do with line strength ?

People answered and you are not accepting the fact:

- it is possible to use super thin back lines.

How thin? We don’t know simply coz we don’t know how much we pulling.
Yes, we do how thin. Look at the Mutiny kiteboarding video. Size your lines to exactly the max shown on the gauges, and they may not break. But they will break on a crash, or a gust, or with a heavier rider, or while unhooking.

You can take the advice of a respected manufacture (Flysurfer) and use 160kg back lines, so long as you don't jump. Or Ozone's at 200kg with regular (100hr) replacement.

Again, not trying to berate you or put you down in any way, but do you get the concept of multiple variables in an equation?

The answer, in its simplest form, to your origional question, is "There are multiple variables".
Last edited by Matteo V on Wed Apr 25, 2018 3:18 am, edited 1 time in total.

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downunder
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Re: I need convincing too:) Bar back lines!

Postby downunder » Wed Apr 25, 2018 3:11 am

Matteo V wrote:
Tue Apr 24, 2018 3:34 pm
Really quick, and I'll address the rest of your post directed at me later:

Do you understand the concept of wear over time vs breaking strength. Specifically the example of 200kg lines worn to 50% of their original strength yield 100kg breaking strength, and 300kg lines worn to 50% of their original strength yield 150kg breaking strength?

Take that down to internal abrasion at a sleeved loop - 200kg lines worn to 20% of their original strength yield 20kg breaking strength, and 300kg lines worn to 20% of their original strength yield 30kg breaking strength.

I think I do "know" you and your are thinking "that is only a 10kg difference". But that is 1/
Hmm,

You are hard man to argue with. Ffs I am not talking about degradation, what this has to do with line strength ?

People answered and you are not accepting the fact:

- it is possible to use super thin back lines.

How thin? We don’t know simply coz we don’t know how much we pulling.

Stop hiding behind general answers we all know. We passed that point years ago.

The question is simple: how much we pulling?

Stop before u answer since the question is not about the safety you are pushing as your argument.

I will repeat, if your argument is safety the bladder should be rated to 100psi or more. But it’s not. The bladder is also degrading and abradding...enough said.

I see your reply now, you are avoiding to answer again with generalisation we all know.


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