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Chockstone Forum - Gear Lust / Lost & Found

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Author
Multi Rope Rapelling Question
Tim_1964
28/02/2013
12:23:42 PM
Hi all, I am studying with a view to rigging up an 80m, single rope (rather than double) abseil at some stage in the distant future by joining two 50m 11m static ropes together. My question - what is wrong with tying a figure 8 on a bight at the end of each static rope (with a long tail) and using a couple of chunky, opposed screwgate carabiners to join the 2 figure 8 knots together? I ask the question because this appears to offer similar protection to the two screwgates used at the top of a top rope. Also, its clean, easy to check, simple etc. If possible please describe risks, hazards with the join. (by the way I just reviewed 101 ways to die abseiling lol so basics are understood.) Thanks : )
hotgemini
28/02/2013
12:33:42 PM
Nothing fundamentally unsafe, just more complex than it needs to be.

In my opinion there is both elegance and safety in simplicity. In the most general and generic terms simple things are easier to setup, easier to inspect and offer less opportunity for issues than an alternative, more complex solution.

-Adam.
gfdonc
28/02/2013
12:43:24 PM
The setup is strong enough and safe enough IMHO, even though I wonder why you'd want to. The simplicity and robustness of tying two ropes together makes it a better solution.

Nevertheless, you may want to consider
- how are you going to throw the rope down? There's a large number of climbers that believe that dropping a krab 50m is reason to discard it. I don't necessarily agree, but you need to consider the karabiners getting damaged in the process
- or cross-loaded? Screwgates are particularly prone to cross-loading as the screwgate can hold the rope/sling in position. If you're rapping in from the top, you can check them when you get there, but if you were ascending such a rope I'd want to know the biners were sitting correctly before I started up.
Olbert
28/02/2013
12:53:10 PM
As I understand it you would like to do a single 80m abseil using two 50 metre ropes tied together.

There are a couple of reasons why you would not do this:

1. When you get to the point where you have to pass 'the knot' (though in this case it's two knots and a couple of lockers) you have a greater distance which you have to skip over which will make it harder and possibly dodgier. In passing a knot on abseil you have to stop above the 'knot', sit on a prussic, undo your abseil device, re-do your abseil device below the 'knot', then unweight your prussic and re-weight your abseil device (normally done with another prussic below). If the clean bit of rope on the other side of the knot is too far down this task will be very difficult and will involve some dodgyness. Even if it isn't a long enough distance to necesitate dodgyness it will definitely make the process harder.

2. You are adding in more links to the chain which can go wrong when there is no reason to. The traditional way of joining two ropes involves one knot - one point of failure. Your suggested way involved two knots and with a double locking biner connection - three points of failure. Though the increase in danger is not much, it is generally a bad policy to increase danger for no benifit.

I would suggest that you tie the ropes together using a double fishermans knot. You might be able to use a Euro Death Knot (dont get scared by the name!) as this has some advantages over the double fishermans and is used in normal double rope abseiling but I'm not sure of it's application on joining two ropes for a longer abseil.

Edit:

I am not giving a lesson on how to pass a knot, if you want to learn how to pass a knot there are much better explanations out there. I would recomend (if you haven't already) learning how to and then practicing passing a knot somewhere close to the ground where you can bugger it up and not die.
Tim_1964
28/02/2013
12:59:09 PM
Thanks so far : ) I havent worked out how I would recover the setup yet - probably by going back up top but that sux....hmmmmm. I guess I am nervous about using a knot to join ropes even tho its best practise. Slippage, friction....not if done right I know. The other thing is I am currently thinking that using F8 knots wherever possible keeps my technique standard in all relevant situations. I used to use clove hitches to assist in building adjustable natural anchors - they work fine but a mate convinced me to change to using an F8 on each anchor which I now do. Anyway, thanks again.

Point noted re complexity - that is a convincing enough argument.
uwhp510
28/02/2013
1:17:52 PM
So you don't trust knots but you'd rather have two than one?

Sounds legit :)

martym
28/02/2013
3:58:14 PM
Where do you want to abseil?

That will give most people an impression of:
-the set up that best suits you
-the length you'll need
-the retrieval options

Someone on Chocky's bound to have been to the spot you want to jump off...
Dave_S
28/02/2013
4:11:57 PM
On 28/02/2013 Tim_1964 wrote:
>The other thing is I am currently
>thinking that using F8 knots wherever possible keeps my technique standard
>in all relevant situations.

That's a bit limiting, but you can use a single figure-8 to join two ropes just as easily as tying in to your harness - the figure-8 bend.

However most importantly, you and anyone else attempting this will need to learn how to pass a knot during an abseil. Read up on how to do this, and then practice it on flat ground first. Half way down an 80m abseil is no place to realise that you don't actually know how to get past the knot in the rope. Even worse would be realising at the same time that you also don't know how to ascend a rope.
One Day Hero
28/02/2013
4:12:33 PM
Dude, just go ahead and do it with the technique you have described. It isn't orthodox, it isn't the most efficient way, but it also isn't any more dangerous than the "correct way".

I did plenty of odd shit when I was learning which wasn't in "how to climb" books. Some of it was sketchy, most was benignly eccentric. Working stuff out for yourself is good for the brain.

The good Dr
28/02/2013
4:36:33 PM
How you join the ropes together is important. How you are going to pass the join is much more critical as it does involve detaching and re-attaching yourself to the rope. How are you thinking of achieving that?

E. Wells
28/02/2013
4:43:09 PM
Get a mate to lower you, extend lowering device with autobloc from anchor w/ schlong and put a munter behind overhand knot (joining knot), as knot approaches engage autobloc , hold end of rope behind munter, take off lowering device, bump then dismantle autobloc one handed and continue to lower. Use good edge protection and your mate can then dismantle the whole rig (which, with the right tree, consists of two schlongs, one prussic, four carabiners ,an ATC, and two ropes) and throw the whole lot in a disorganised bundle 80mtrs down to the canopy and you can continue on your merry way.

IdratherbeclimbingM9
28/02/2013
5:14:35 PM
On 28/02/2013 E. Wells wrote:
>Get a mate to lower you, extend lowering device with autobloc from anchor
>w/ schlong and put a munter behind overhand knot (joining knot), as knot
>approaches engage autobloc , hold end of rope behind munter, take off lowering
>device, bump then dismantle autobloc one handed and continue to lower.
>Use good edge protection and your mate can then dismantle the whole rig
>(which, with the right tree, consists of two schlongs, one prussic, four
>carabiners ,an ATC, and two ropes) and throw the whole lot in a disorganised
>bundle 80mtrs down to the canopy and you can continue on your merry way.

... except for 'mate' at the top.

The posts above who point out the issues with passing a knot are on the money. For the uninitiated this can sometimes prove to be a massive hurdle, so much so, that it may be easier to simply buy a longer rope!
Tim_1964
28/02/2013
5:34:13 PM
lol, yes, fair point - the logic has now dawned on me. : )
Tim_1964
28/02/2013
5:48:12 PM
lol, thanks again all - I learnt what was called a 're-belay' on a 40m pitch in Midnight Hole cave near Lune River, Tas. I was using a rack descender, was 10m down and put the rack on upside down....anyway, now very comfortable with up, down, and around knots but will be building up and testing on a tree and smaller rock before going live. Regarding the project - hard to explain - what do you do when you find a bloody great mountain (or two) that no-one seems to have climbed....possibly cos its unclimbable - yet to be determined. My brain cant get the notion that there is soooo much rock on these two mountains - surely it cant all be choss lol. probably is. but still, there is a mountain to be climbed. I just have to work out how. Trad looks iffy cos of choss. Another interesting thing is that I have been doing a lot of self belay with a croll and a couple of prussiks, backed up by F8 knots on a second rope every 3m. So anyway, how does one climb a mountain if trad wont work lol........so should I rap in and then climb using the rope as a 'fixed rope' and self belay - philosophical/rhetorical question....

E. Wells
28/02/2013
6:30:17 PM
Bolt the shot out of it.
Tim_1964
1/03/2013
9:36:36 AM
hahahaha - yes indeed, bolting......an interesting philosophical conclusion ; ) and suppose its in World Heritage area lol.
Wollemi
1/03/2013
10:50:13 AM
On 1/03/2013 Tim_1964 wrote:
>hahahaha - yes indeed, bolting......an interesting philosophical conclusion
>; ) and suppose its in World Heritage area lol.

Will that constrain you? The Grose and Wolgan valleys have substantial areas of WH listing. And bolts.
http://www.environment.gov.au/heritage/laws/publicdocuments/pubs/105999.pdf


There's nothing philosophical about it. It just is. Happening.
Tim_1964
2/03/2013
7:09:42 PM
Cool, best get a Hilti then. Thanks all.
Tim_1964
2/03/2013
7:12:03 PM
Not sure how this got to the Gear Lust page but thanks anyway.

There are 19 messages in this topic.

 

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