From: AWaddington@acorn.co.uk (Andy Waddington)
Newsgroups: rec.climbing
Subject: Re: Gibbs Ascender - Top Ropeing???
Date: 7 Apr 92 00:53:31 GMT
Distribution: rec
Organization: Acorn Computers Ltd, Cambridge, England

shoop@wocket.spcssi.sequor.com (Dhan) writes:

>mercer@ncs.dnd.ca (David Mercer) writes:
>> 
>> I just acquired a Gibbs Ascender. Can this device be safely used for 
>> solo top rope climbing?
>> 
>
>The Gibbs ascenders (actually all ascenders I know of) are not designed to
>withstand a fall. The are static rather than dynamic devices. A fall is a 
>dynamic event on a climbing rope.
>
>You could attach the rope at the top and "ascend" the rope while you climb,
>just be careful to make sure you don't leave much slack in the rope. Too
>much could be dangerous in a fall since ascenders aren't supposed to stop
>a fall.
>
>BTW, the Gibbs, due to its design, is better at this than most ascenders
>since your weight is directly on the rope as opposed to the way jumars
>handle this.
>

This is a problem faced by cavers using ladders who choose to use rope the
same length as the pitch rather than doubled through a pulley. You hang a
single rope down the pitch, then clip an ascender to the static rope and
climb up. In theory, no slack is allowed into the system. You can sit down
for a rest anytime or you can fall (or the ladder can break).

In a climbing situation, much the same applies, except:

1) If you are using a dynamic rope, sitting down for a rest is more of a
pain, because it stretches more.

2) By the same token, if you fall, there is a lesser load on the ascender
and rope because of the stretch.

3) Since rock climbs aren't straight up and down, as a caver's electron
ladder usually is, slack CAN get into the system because:
 a) the rope goes up under an overhang at an angle
 b) non-upright body position means the ascender doesn't slide up the rope
    as you would hope.

 cavers solve (b) by tying a weight to the bottom of the rope, or having
 someone hold it for them - in climbing you just have to be careful to make
 sure you feed any slack through whenever you get the chance. Both (a) and
 (b) make this technique rather less safe on pitches with many zig-zags,
 traverses or roof overhangs. In short, all the places where you would
 normally find it much better to lead with double ropes.

4) Climbing ropes are usually no more than 50m, so this technique is only
really applicable to single pitch climbs where you can reach the top by a
safe approach.

As to the ascenders: sprung cam ascenders (either the forged type like CMI,
Clog, Petzl... or cast ones like jumars) don't take well to falling loads
at all. The cam can shatter or flip right through the ascender, which both
kill you. Direct loading cam devices like the Gibbs are much stronger in a
fall, but can apply very large forces to the rope, in the extreme case
cutting it completely. For both these situations, the rule is not to allow
any slack in the system - so stick to vertical cracks or straight up face
climbs.

The further advantage of a Gibbs over a sprung-cam ascender is that it feeds
up the rope much more easily, since every upward movement you make unloads
the cam. Conversely, if you are careful, you can downclimb without the cam
grabbing, which is obviously useful when you are tentatively trying out a
move. The corollary of this is that you do have to FALL, not just slide
slowly, for the Gibbs to grab and stop you. It is possible to grab the
Gibbs with one or both hands as you start to go, and THIS CAN PREVENT IT
FROM CLOSING.

The final important point is that you should know how to get down if you fall
off and end up hanging by the Gibbs from the rope some way out from the rock.
You need another ascender to do this simply (a prusik knot will do, just).
You can either go up (but prusiking up a dynamic rope on a rock face is not
very good for it) or you can go down (by changing over to abseil). Both
these manouevres need practice to do safely. Get hold of a book on caving
rope techniques to learn how to do them ('On Rope' is the standard work in
the US, I believe), then try them somewhere safe, near the ground (eg. a
small tree in your garden).

Having said all this, I used a Gibbs for solo top-roping on crags up to
about 40m in the evenings near my home when I had no climbing partner over
several years, and found it eminently satisfactory. I fell off numerous
times, and never accumulated much slack, so they were always soft falls. I
had loads of practice at changing from prusik to abseil in the course of a
lot of caving, but never actually had to do it when rockclimbing this way,
since I wasn't up to climbing overhangs in those days. If you bear these
points in mind, and have a bombproof belay at the top, I think its dead
safe. But without an audience, its very easy to cheat and rest on the rope.

Happy self-protection.      Andy.