Descending on a single rope.

[stuartc44]

I had heard somewhere before and on the video linked to on the 'Sirius ringloop?' thread that it is not good to descend with a hitch on a single rope and a second device, figure 8 etc, should be used.

 

Why is this, and why so different to double rope?

[MOG]

because it 1-1 instead of 2-1 on the rope. Single and Double systems, so u would move twice as fast on single than u would on double. so u dont havent time to react if the hitch opens up etc etc, also way more wear on hitch and rope.

 

So just remember twice the movement on Single line systems than u would get on double.

 

hope that makes sense cheers MOG

[geoff]

You would be liable to cook your hitch,they dont disapate the heat generated,which will be more on a single line as its not sharing the load,a fig 8 or similar will provide the friction for a controlled descent & get rid of the heat,the hitch acting as a fail to safe in case you let go.

Thats my take on it.

Edited March 4, 2011 by geoff
missed a bit

[Peter]

Its also quite hard to even get the hitch to move on a single line if you are hanging on it, as its difficult to unweight it and open the hitch up.

 

A mechanical device works much better, and the hitch is just there as a backup really.

[stuartc44]

So a figure 8 connected to the bridge and a long prussik loop above the figure 8 would be a good / cost effective choice.

 

Thanks for the explanations, does make sense now.

 

Stuart.

[Peter]

Why do you want to descend a single line?

 

A figure eight on a sling works well with a short hitch too.

[stuartc44]

I was thinking that using the technique in the video in the 'Sirius ringloop?' thread, after topping a tree for removal, I could descend from the tree and retrieve my rope ready for felling at a later time.

[Peter]

I do that, but I just put a fig 8 type device on above my vt.

 

In fact, I normally tie a bowline with a long tail in the spliced eye end of my climbing line, (long enough tail to reach the ground), put a biner in the eye of the bowline and choke off my climbing line, then descend as described, then use the long tail to retrieve the system.

 

Not the best setup but ok for infrequent short descents, imo.

[stuartc44]

We should have a job coming up which will be getting a number of trees topped ready for felling so will definitely give it a try.

[Jonny69]

I tie a running bowline around the top of the tree with the rigging rope, then descend on that with a figure8. Ready to pull over when you get down.

 

This way also means you dont need to leave any stubs to put the your climbing line round.

 

If I am hand pulling the stick over then I just use my climbing line instead of the rigging rope. Although 9 times out of 10 the rigging line is already out so it gets used.

 

You can back up the figure8 with an 8 wrap prussic or similar knot to be extra safe but I have never bothered.

 

EDIT: Forgot to say dont descend off a single line with a VT/prussic/lockjack etc. You have to take you weight off to get it to move and then drop about 10feet before you have chance to realise your mistake and let go of the hitch. I saw someone do it on a double footlock line and very nearly smash their head on a buttress as they flipped over in the harness when the hitch regripped.

 

The only way to descend off a single line safely without a fig8 (or similar) is to use the footlock position and your feet as the friction device to lower yourself whilst holding the hitch open, which wears out boots really fast.

Edited March 7, 2011 by Jonny69