22kn Loop Runner Redirects

L

Leon

Location
rambling
A friend of mine recently asked me if I thought 22kn loop runners could be used as redirects and still be withing ANSI/OSHA standards. I told him it probably depends on what configuration the loop runner is tied/girth hitched.

I am hoping that I can get a definitive answer here. I figure it's allowed at ITCC it's up to snuff.

Thanks.
 
I'm not prepared to look, but I'll try to explain? Clip a krab to one side of the sling. Wrap it around a limb and clip the other side to the same krab. Cool? It makes the sling double thick this way, adding strength, rather than chocking it off and taking some away. It's just like holding each end of a loop in each hand. Then put your hands together.
 
Knots_26_Basket_Hitch.jpg



Clear things up?
 
This is just a thought but... If you're still tied-in at your original TIP, why would it really matter what the strength of your redirect is? All I ever use is a loop runner from Sherrill and a non-locking krab.
 
I suppose there is the risk of a break (although I know my boucing around doesn't ever equal 22kn) in which case you would probably swing uncontrolled about the canopy of the tree.
 
In some circumstances you will be less likely to have more than your own weight on a redirect point. However, there are some times when you may have more on a second point or redirect than your original point. It really depends on angles and friction.
 
I'd second Mark enthusiastically on that ! Redirets are often viewed as being like a back-up, having to support less loading. So we choose lower dimensioned TIP's, and lower spec materials.

This is wrong!

As Mark says, depending on the exact configuration, method of redirect and positioning of the climber, the redirect may end up with a larger load on it than the main anchor.
Depending on the situation you're in, you really don't want to risk snapping a redirect, due to risk of, say, a pendular fall... or else you wouldn't go to the effort of redirecting, would you ?!

Redirect TIP's and materials should be considered exactly in the same fashion as you would a main anchor point.
 
Well said. I'd also add the idea that if a redirect did fail, it might be worse than not using one at all. What I mean is that you may be more vulnerable in that you are trusting that point to support you. If it were to break, imagine the outcome. More slack in the line (usually) and a huge swing/drop. /forum/images/graemlins/ahhhhh.gif
 
At a chapter TCC one of the competitors had a sling on his saddle with a non-locking biner. I did his gear inspection and asked him what that was for. He said a re-di. I told him that he couldn't use it and he got really cranked. Told me that all of the climbers at the company he worked at did it that way. I explained that the re-di was part of his climbing system and had to meet the same standards, 5,400# just like ropes. He came pretty close to getting DQ'd because of his confrontational attitude.
 
If I'm correct, if the angle of the two ends of rope exiting the redirect are anything less than 120 degrees, you'll have a load at the redirect > than your weight. At the last Arbormaster class they did a neat demo showing how at 0 degrees you're roughly double (TIP or butt hitched vertical spar), but as you open up the angle, the load (at the redirect or rigging point)decreases. At 120 degrees the load is roughly (depending on friction) equal. So, if your redirect is at 90 degrees load at redirect is increased. Blah blah.... /forum/images/graemlins/smile.gif
P.s. I think it's strange that suppliers even display/sell biners and what not that are 22kn alongside properly rated ones. I think 22kn is only about 120# shy, but a standard is a standard.
 
[ QUOTE ]
at 0 degrees you're roughly double

[/ QUOTE ]

That is slightly different than I know it. Most sources I have would call 180* 2 x the load. Maybe I'm just getting carrired away here. Good point to bring up though!
 
[ QUOTE ]
Quote:
--------------------------------------------------------------------------------

at 0 degrees you're roughly double


[/ QUOTE ]



[ QUOTE ]
Most sources I have would call 180* 2 x the load.

[/ QUOTE ]

That's a good thing to mention. I don't know why, but that's the way that ArborMaster seems to teach forces created by rope/sling angles. That's also how it appears in the video/workbook The Art and Science of Practical Rigging (ASPR). The reference point (0*) for them is 180* from where the reference point is for other sources. It's particularly confusing when looking at when the angle creates a force that is 1X (equal to) the load. ASPR says that the force on the sling is equal to the load when the angle is 120*, while other sources say it is when the angle is 60*.

Mahk
 
I think it works out that the rope creates two legs of the angle, and the rigging point is the vertex, if that makes sense. I'd do a cute little diagram on here if I knew how. /forum/images/graemlins/smile.gif
 
You must log in or register to reply here.

New threads New posts

Back
Top Bottom