3:1 rig for ascending / hauling / rescue
Posted: Sun Jan 07, 2024 9:00 pm
The physics behind this system mean that the mechanical advantage created by the pulleys provide a three to one ratio. Basically, the object being hauled up (that could be you) moves 1/3rd the distance you pull but only requires 1/3rd of the effort it would require to just pull it straight up on a rope with no pulleys.
I set this up in my practice space and found it to be a lot easier than ascending using a hand ascender and a foot loop with a progress capture device, but in the field on a 50' climb I found it was still pretty tiring to pull myself up. At first I thought there might have been some twisting of the ropes but after further inspection it seems like it's just a lot of work to ascend that way. Perhaps the length of the ropes on a 50' climb vs the 20' practice space contributed to that. If nothing else, it's still a good rig for pulling someone up, or for lifting packs.
One trick I used in the practice space but forgot in the excitement of the actual climb was using a hand ascender to pull on the rope. Just hold the tail in your non-dominant hand so the ascender easily slides up the rope and use your dominant hand to slide the ascender up and then pull down on the rope. Doesn't provide any real advantage but certainly makes it easier/more ergonomic to grip the rope when pulling yourself up.
I used a Petzl mini traxion pulley on the harness as a progress capture device. This is EXTREMELY important so that if you need a rest or let go of the rope for any reason, you don't fall. Without it, if you were to replace the progress capture pulley with a regular pulley, you would drop all the way down to the ground with no significant resistance if you were to lose your grip on the rope. This would probably seriously injure or even kill you.
You could substitute the double pulley with two single pulleys if you wanted, but that would increase the complexity of the rigging and may increase the risk of tangling.
I drew this out for better visualizing what's going on, but when I get a chance I'll lay it out and take a picture of the actual gear.
I set this up in my practice space and found it to be a lot easier than ascending using a hand ascender and a foot loop with a progress capture device, but in the field on a 50' climb I found it was still pretty tiring to pull myself up. At first I thought there might have been some twisting of the ropes but after further inspection it seems like it's just a lot of work to ascend that way. Perhaps the length of the ropes on a 50' climb vs the 20' practice space contributed to that. If nothing else, it's still a good rig for pulling someone up, or for lifting packs.
One trick I used in the practice space but forgot in the excitement of the actual climb was using a hand ascender to pull on the rope. Just hold the tail in your non-dominant hand so the ascender easily slides up the rope and use your dominant hand to slide the ascender up and then pull down on the rope. Doesn't provide any real advantage but certainly makes it easier/more ergonomic to grip the rope when pulling yourself up.
I used a Petzl mini traxion pulley on the harness as a progress capture device. This is EXTREMELY important so that if you need a rest or let go of the rope for any reason, you don't fall. Without it, if you were to replace the progress capture pulley with a regular pulley, you would drop all the way down to the ground with no significant resistance if you were to lose your grip on the rope. This would probably seriously injure or even kill you.
You could substitute the double pulley with two single pulleys if you wanted, but that would increase the complexity of the rigging and may increase the risk of tangling.
I drew this out for better visualizing what's going on, but when I get a chance I'll lay it out and take a picture of the actual gear.
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