Rope support with tuber: Difference between revisions

Line 61:

== Efficiency note ==

As the ATC adds a lot of friction to this system, the pulley theoretically gives only 2:1 leverage as only the belay strand part of the rope which is behind the ATC is active during pulling. However, 3:1 length of slack relative to lift height must be taken, as the rope must still be pulled through the ATC. Real world testing done by John Gordino (Alpinesavvy) shown that in reality, due to a friction, it provides only roughly 1.5:1 leverage.<ref name=friction_alpinesavvy>{{cite web | url=https://www.alpinesavvy.com/blog/progress-capture-efficiencies-of-various-devices | title=Progress capture - efficiencies of various devices | publisher=Alpinesavvy LLC | first1=John | last1=Godino | website=AlpineSavvy.com | access-date=27 September 2025 | url-status=live | archive-url=https://web.archive.org/web/20211119020952/https://www.alpinesavvy.com/blog/progress-capture-efficiencies-of-various-devices | archive-date=19 November 2021}}</ref> That means that for a 75 kg climber, 50 kg of weight has still to be pulled up with three times the length of the rope to be pulled compared to system without the pulley.

As the ATC adds a lot of friction to this system, the pulley theoretically gives only 2:1 leverage as only the belay strand part of the rope which is behind the ATC is active during pulling. However, 3:1 length of slack relative to lift height must be taken, as the rope must still be pulled through the ATC. Real world testing done by John Gordino (Alpinesavvy) shown that in reality, due to a friction, it provides only roughly 1.5:1 leverage.<ref name=friction_alpinesavvy>{{cite web | url=https://www.alpinesavvy.com/blog/progress-capture-efficiencies-of-various-devices | title=Progress capture - efficiencies of various devices | publisher=Alpinesavvy LLC | first1=John | last1=Godino | website=AlpineSavvy.com | access-date=27 September 2025 | url-status=live | archive-url=https://web.archive.org/web/20211119020952/https://www.alpinesavvy.com/blog/progress-capture-efficiencies-of-various-devices | archive-date=19 November 2021}}</ref> That means that for a 75 kg climber, 50 kg of weight has still to be pulled up with three times the length of the rope to be pulled compared to system without the pulley. That is the reason why this pulley system gives only enough of support to help the climber with a difficult move, but does not enable to pull the climber up in more severe rescue scenarios.

== References ==

@@ Line 61: / Line 61: @@
 == Efficiency note ==
-As the ATC adds a lot of friction to this system, the pulley theoretically gives only 2:1 leverage as only the belay strand part of the rope which is behind the ATC is active during pulling. However, 3:1 length of slack relative to lift height must be taken, as the rope must still be pulled through the ATC. Real world testing done by John Gordino (Alpinesavvy) shown that in reality, due to a friction, it provides only roughly 1.5:1 leverage.<ref name=friction_alpinesavvy>{{cite web | url=https://www.alpinesavvy.com/blog/progress-capture-efficiencies-of-various-devices | title=Progress capture - efficiencies of various devices | publisher=Alpinesavvy LLC  | first1=John | last1=Godino | website=AlpineSavvy.com | access-date=27 September 2025 | url-status=live | archive-url=https://web.archive.org/web/20211119020952/https://www.alpinesavvy.com/blog/progress-capture-efficiencies-of-various-devices | archive-date=19 November 2021}}</ref> That means that for a 75 kg climber, 50 kg of weight has still to be pulled up with three times the length of the rope to be pulled compared to system without the pulley.
+As the ATC adds a lot of friction to this system, the pulley theoretically gives only 2:1 leverage as only the belay strand part of the rope which is behind the ATC is active during pulling. However, 3:1 length of slack relative to lift height must be taken, as the rope must still be pulled through the ATC. Real world testing done by John Gordino (Alpinesavvy) shown that in reality, due to a friction, it provides only roughly 1.5:1 leverage.<ref name=friction_alpinesavvy>{{cite web | url=https://www.alpinesavvy.com/blog/progress-capture-efficiencies-of-various-devices | title=Progress capture - efficiencies of various devices | publisher=Alpinesavvy LLC  | first1=John | last1=Godino | website=AlpineSavvy.com | access-date=27 September 2025 | url-status=live | archive-url=https://web.archive.org/web/20211119020952/https://www.alpinesavvy.com/blog/progress-capture-efficiencies-of-various-devices | archive-date=19 November 2021}}</ref> That means that for a 75 kg climber, 50 kg of weight has still to be pulled up with three times the length of the rope to be pulled compared to system without the pulley. That is the reason why this pulley system gives only enough of support to help the climber with a difficult move, but does not enable to pull the climber up in more severe rescue scenarios.
 == References ==