Why does abseiling become easier gradually?

Question

When I am abseiling, the rope is initially hard to feed through my braking device - if I take my hands away from the rope, I get stuck in mid-air.

However, as I am getting lower, it gradually gets easier, until at some point the rope starts running by itself. Now, if I took my hands away from the rope (thought experiment - imagine I have no backup braking device), I would accelerate down and hit the ground very hard.

Why is this so? The rope is vertical, and I don't touch any wall, and yet it somehow matters whether I am situated high or low on the rope.

I am abseiling on a static rope, the height is 60 meters. Just to make it clear - the wall is absolutely vertical, and then somewhat overhanging, so the wall doesn't hinder my progress in any way.

ShemSeger · Accepted Answer · 2016-02-24T03:40:36.467

20

The simple answer is the weight of your rope.

When you're at the top of a pitch, you will have the full weight of 60m of static line below you, braking on your device. As you move down the rope, there is less and less rope below you, ergo less weight and friction on the braking end of your device.

To avoid this, as well as any possible rope entanglements from throwing your rope over the side of a cliff, you can rappel with your rope flaked out nicely in a sling clipped to the side of your harness, and let it out as you descend, this eliminates the extra weight on the device:

^{Learn This: Alpine Rope Management}

edited Feb 24 '16 at 03:40

answered Feb 22 '16 at 20:20

ShemSeger

53,549
10
123
296

Just to make it clear - the rope in your picture is a dynamic rope, right? – anatolyg Feb 22 '16 at 20:22
@anatolyg In this photo, yes, but I've used this method for descending dirty limestone cliffs in the windy Rockies with 11mm static lines. Works great. – ShemSeger Feb 22 '16 at 20:30
7

Just make sure that when you flake out the rope, that the loops on the bottom are longer than the ones stacked on top of them, or else you'll end up part way down the pitch with a huge knot to untie one handed. – ShemSeger Feb 22 '16 at 20:32
2

Nice to see they tied knots at the ends! – Chris Mendez Feb 23 '16 at 03:30
People most using static ropes (cavers) use a rope bag hanging below them. Much more comfortable. – Vladimir F Героям слава Jun 14 '16 at 08:17

Why does abseiling become easier gradually?

1 Answers1