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DB Tree drop tests confirm Rope Wrench grip-ability

Richard Tregoweth - Monday, January 16, 2012

Working the tree on a single (leg of your climbing) line has always polarized climber opinion.

Now, with increasing popularity for the Rope Wrench the SRT issue is coming into much sharper focus.

While the Rope Wrench might be renewing interest in working SRT it is not without its critics.

Of course, healthy debate is a good thing but it does get a little silly when the criticism is unfounded and unproven.

One such notion is the view that the Rope Wrench system (which includes the friction hitch) would run uncontrollably down the climbing line in the event of a fall.

Treetools is not sure where this idea originated but it flies in the face of known facts: a friction hitch will typically bind so tight on a single line, when loaded excessively, it renders the knot immoveable.

That is the very reason the Rope Wrench exists - the Wrench distributes the friction so that the knot will not bind… but not to the point where the system will run uncontrollably.

Regardless of logic, the idea the Rope Wrench and friction hitch might release its grip and slide down the single leg of the climbing line rapidly became 'urban legend' in tree climbing circles.

So there was only one thing to do - test the theory!

On Saturday, January 14, 2012 in the Auckland Domain Drew Bristow from DB Tree did just that.

With borrowed Olympic weights from Treetools, 80kgs was dropped into the Rope Wrench system with a fall factor of 1.5 which generated around 13.5 kN of force according to the Fall Force and Impact Calculator.

You'll have to cock your head sideways to the right but you can see in the video below the Rope Wrench and friction hitch barely move on the line. According to Drew, the hitch released immediately after the fall and continued to behave as normal.

There are plans to replicate the DB Tree Rope Wrench drop test (to get better video footage) and Treetools will also put the system on the test bed to determine the precise point of slippage.

These tests are not exactly scientific but with both bits of information the 'grip-ability' argument should, at least, be rendered redundant.

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