Hi-lining: some interesting info

Jack

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<iframe width="560" height="315" src="//www.youtube.com/embed/cObvjbVO3ro" frameborder="0" allowfullscreen></iframe>
 
http://www.youtube.com/watch?v=cObvjbVO3ro&feature=player_embedded#t=354

That's the part that I have some notes to. When you add one more rope to the system, the load on the anchor point (which, as we all saw, depends on the angle) stays the same. It just distributes between the two ropes, on which the load is applied.
No matter how many ropes you put - 2 or 20, the load on anchor point depends mainly on the rope angle.

(btw there is a chance that my language skills have prevented me to understand what exactly the guy says. If that's the case - sorry :|: )
 
That is why it can be so effective to tension a pulling line, snub it off and then pull sideways to get the pulling force you need in more relaxed and safe manner.

Jean worked with Leilak the other day, a little intimidating to have the Quebec champ run the ropes. Sends a shoutout to Matt...
 
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http://www.youtube.com/watch?v=cObvjbVO3ro&feature=player_embedded#t=354

That's the part that I have some notes to. When you add one more rope to the system, the load on the anchor point (which, as we all saw, depends on the angle) stays the same. It just distributes between the two ropes, on which the load is applied.
No matter how many ropes you put - 2 or 20, the load on anchor point depends mainly on the rope angle.

(btw there is a chance that my language skills have prevented me to understand what exactly the guy says. If that's the case - sorry :|: )

Great point, combrig! I was worried he'd pull one of those bricks out of the wall and ... get flattened. :\:

BTW ... your language skills are fine ... prolly better than mine :thumbup:
 
Is he saying that adding multiple lines, but still anchored to the same points, will reduce the force at those same anchors? So the only difference would be an additional rope.

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This is why you have to be so careful with tensioning zip lines with mechanical devices. As the sag approaches zero the tension becomes infinite!!!
 
Is he saying that adding multiple lines, but still anchored to the same points, will reduce the force at those same anchors? So the only difference would be an additional rope.

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No, he's saying the gear will see lower loads. The anchor points (assuming both ropes are connected to the same anchor point) will still see the same loads. However if the two ropes are attached to different anchor points, then the force on each anchor point could be reduced.

Question: When setting up a high line in the past I have used prusiks to lock the position of my tie in on the high line in order to be suspended directly over the working area. This means that my load is not centered directly in the middle of the highline as it was in his demonstration. In this case would the load be different on the two anchor points or would it still be shared evenly? I assume that some basic trigonometry would tell me the answer, but I've forgotten all of that now.

Thanks for sharing the video, Jack. It's a good one.
 
I assume that some basic trigonometry would tell me the answer, but I've forgotten all of that now.

They aren't the same in locked load were it doesn't find center.
But if remember right from rigging calcs the flatter line is not seeing a higher load because it is acting more like a guy line. Where as the steeper line ie the one you are closer to the anchor point on, is seeing the higher load.
 
They aren't the same in locked load were it doesn't find center.
But if remember right from rigging calcs the flatter line is not seeing a higher load because it is acting more like a guy line. Where as the steeper line ie the one you are closer to the anchor point on, is seeing the higher load.


That was my feeling from my experience using the system, but just wanted to see if the math agreed. Thanks.


With trees we have to think about the angle of the load in relation to the branch, as well, i.e. which way is the branch being compressed/pulled.
 
High lines.png
This is what I have done in the past, I assumed using two rope up high, ( the red and blue) would reduce the tension as opposed to one rope. is this correct thinking?
 
This is why you have to be so careful with tensioning zip lines with mechanical devices. As the sag approaches zero the tension becomes infinite!!!
PC you got me curious about the zip line or speed line thing. I understand what the gentleman in the vid was saying about suspended loads, but what about a rolling load going downhill? My brain wants to tell me that since it's moving, and obeying the law of gravity, that the tension on the speed line would be less than if it was holding the same weight as a stationary load and as the angle increases, the tension decreases. My brain has got me in trouble before so without doing my own test, I'm asking this question to the vast horde of mathematical Einsteins reading this post.
 
that cable demonstration makes me wonder about the loads involved with skyline logging. The load at the tail-hold must be tremendous!
 
I can't figure the vectors at the moment, but I don't think you're better, worse actually, as you will, at best, have a splice, and worst, a knot at the connection in the middle.

Limbrat, I don't think you're really saving much, if anything. Only a little because its not arresting the fall in the case of a uncontrolled zipline (no brake line). A very flat zipline is going to have much higher forces than a near vertical zipline.
 
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