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Dilz

What are the dangers of using SRT?

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makes sense - more rope = more stretch = more force absorbtion.

 

Its easy to see how much difference there is just by comparing ascending on a base anchor vs a top anchor - though why any one would fall with slack intheir system is beyond me... :/

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found this about forces on anchor points - i had to sign up and log in to treebuzz to be able to view the slide from Petzl

Petzl preliminary research | The BuzzBoard

'when climbing SRT od Ddrt system the force applied to the top anchor is approximately 50% greater than the weight of the climber

 

When climbing on a SRT with a base anchor, the force applied to the Primary suspension point is approximatly 50% greater than the force applied to the top anchor when climbing on an srt or ddrt system

 

falling on an SRT with base anchor will genertate a longer free fall and deceleration compared to falling on a srt and Ddrt with top anchor.

 

falling on a Ddrt system can generate 60% to 70%higher forces on a top anchor point (and on the climbing system and climber) compared to the forces generated on a primary suspension point when falling on a SRT with a base anchor.'

 

I wondered if the force on a top anchor when ascending ddrt is different when using natural crotch compared to a pulley saver, then decided life is too short to get bogged down with the details

 

When using en rated ropes on a base tie then yes but when using a much more static rope then no, you can generate some serious force on a base anchor when using a rope with less stretch . A natural crotch for an anchor takes away a lot of the doubling, most of the time with a fork in the perfect position directly above with lines parallel you will will be lucky to get 1.5 x the force, this is changed when you take a fall in the line or load it heavily with two climbers(pre climb check). when this happens the friction at the top its taken away and does little to nothing(on a very static line, on an en rated rope.. its no so dramatic) but i found it never to get above 1.8x even on a very small crotch with barely any friction and loaded with two people.

 

Base tying srt is a tricky one. One thing that should also be noted when using natural redirects is the force exerted on the anchor points when redirects are being forced together e.g. when traversing through two skinny tall trees or skinny long leaders , not only is your weight on there but the actual force of the trees flexing and wanting to get back to their natural position too. It can sometimes be a much larger amount of force then you'd expect. @marc i really enjoyed reading your posts dude, knowing where and how to add friction along your climb can allow you to anchor places you couldn't safely anchor on a traditional toptie. I climb with very static ropes and majority of my srt climbing is done on a base tie.

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