UKC

Last year I did a little bit of basic multipitch with an MIA aspirant. In that session, he suggested I belay from the rope loop on my harness (tied with a rethreaded figure 8), rather than the belay loop.

I have dwelled on this, and something is bothering me. Belaying the second, the forces involved are likely to be fairly minor. Belaying a leader, however, can as we all know create higher forces on the belay loop (or in this case, the figure 8 loop).

My concern is that this will "ring load" the figure 8, i.e. try to pull the loop out sideways. This is the same loading scenario that gains the figure 8 bend the name of "death knot", because it will capsize easily in that loading scenario. Once a figure 8 has started to capsize, it can keep going, capsizing end over end until it runs out of rope, and the whole thing comes undone.

Intuitively, a figure 8 won't capsize over a stopper knot, but you'd still end up with a complete mess that may be almost impossible to untie.

So I am wondering: what is the rationale for belaying from the rope loop like this, given the likelihood of loading the figure 8 in a way that we know is prone to failure, and is it standard practice to teach mulitpitch climbing using this technique?

In reply to sarahlizzy:

I was instructed that way during a two day private instruction with a qualified MIA.

My understanding is that the reason for using the rope bight (loop as you called it) is because it is seamless (has no stitching and no 'end') and because it will increase the life of the harness by putting frequent wear onto the rope instead of the harness.

I have held many falls (largest was about 8 metres) and under no loading that I have experienced have I had any 'capsizing' or difficulty in releasing the knot.

In reply to sarahlizzy:


It works, it's convenient and there isn't a history of accidents would be my guess.

jk

In reply to EZ:

Thanks. Interesting points (although I'm not sure why one wants to favour the life of the rope over the harness - ropes cost more!).

The question remains though - the figure eight on the bight is the loop knot version of the death knot. Nobody with any sense and a desire to live would use the death knot to join two ropes (I mean the true death knot here - the one tied with a figure eight, rather than an overhand - that one is safe if you back it up and use a long enough tail), so why are many apparently content to load the figure eight on the bight in the same way we *know* makes a death knot unsafe?

In reply to sarahlizzy:

Have a look here vimeo.com/40767916

This shows that both a normal fig 8 and a bowline with a stopper can hold more than 700kg when cross loaded. That's 7kN, so should be plenty strong enough.

In reply to sarahlizzy:

The rope can have the end chopped if it does get too warn, but also it has a sheath protecting the bit that takes the load. The belay loop is what takes the load. Wear that out and you either have to add a non-original repair or a karabiner or to get a new harness.

In reply to Monk:

That seems pretty conclusive.

Still a bit disturbing at how soon it starts to capsize (despite never finishing) though!

In reply to sarahlizzy:
Lots about it here - http://www.ukclimbing.com/forums/t.php?t=504392&v=1#x6863219

In reply to sarahlizzy:

The only reason I can think of using the rope loop rather than the harness belay loop is to reduce cluster f*ck on the harness and to give a better chance of load getting transferred in line to the belay. Thats the theory at least. Personall since I always tie off the belay directly to the rop loop (thereby saving on the need fo karibiners on the harness), I belay offf the belay loop.

As for the safety of the ring loaded rope loop, I think the rationale is that the loading is never really 3 way but primarily the force goes from the belay device through to the anchor and the 3 way load is relatively low.

In reply to scott titt:

Exactly the sort of discussion I was hoping for! Many thanks.

In reply to sarahlizzy: Just to note, the video doesn't show the fig8 being pulled in the directions it would be at a normal belay, as one of the lines would be taking the force. It shows what would happen if you put a cow's tail on the rope loop.

It would be hard to really ringload a knot at the belay.

In reply to sarahlizzy:
One advantage of belaying from the rope loop rather than your harness is that it becomes possible for you to get out of the system without undoing the krab. You can tie the crab onto another anchor and then undo the fig 8 on your harness. If the krab is on the harness the only way for you to get out of the system without undoing the krab is to cut the belay loop.

Of course, there are very few times when you will ever want to get out of the system. But when such circumstances happen... If at all possible you don't want to get the knife out because you may want your belay loop later, or you may also cut another strap by mistake.

In reply to almost sane: Just chased Simon Marsh at DMM again so you never know... we might get a scientific answer at some point?

In reply to scott titt: Here - I saw you at Swanage on sunday walking (in our case - running in yours) back from dancing ledge - nice day for it!

In reply to sarahlizzy: A good article on that very topic on this very site: http://www.ukclimbing.com/articles/page.php?id=1129

In reply to sarahlizzy:


But you can chop a metre off the end of a rope which you can't with a harness. I don't like belaying off the rope loop as it is rarely as snug as the belay loop for obvious reasons and it feels like the belay device is flopping about more.

In reply to Hannes: Surely that depends on how tight you pull the loop before you finish tying it? If you tie in with a bowline or a ringbend like I do, you can have a very very small tie in if you want it...

In reply to sarahlizzy:

As the videos and other tests show, ring-loading isn't a problem for figure-8's and bowlines with stopper knots. Moreover, the tests do not properly simulate how the loop will be loaded, which in reality will be, in my opinion, a much less severe form or ring-loading than the tests provide.

But the original question has to do with rationale. The rope-loop belay transfers the load to the anchor directly, whereas the harness loop belay induces various twisting and shearing forces on the harness as the belay loop pulls one way and the harness tie-in pulls the other way.

The rope-loop tie-in works best when the belayer's connection to the anchor is snug. This is best achieved by using clove hitches, which are easily and quickly fine-tuned to eliminate all slack. The method is also very effective for belaying the second, since the weight of the fall is transmitted directly to the anchor, with no load at all on the belayer's harness.

I wish I climbed enough to warrant worrying about wearing out belay loops

In reply to almost sane: why not just escape the system in he normal way?. No one would cut their belay loop.

Intrestingly this very question came up on my SPA training over the weekend, the reasons I was told are 2 fold, to add an additional dynamic element to the system, and secondly, as has aleady been mentioned to assisst escaping the system.