Worth a read. Note how weak a figure of eight can be for joining ropes...
http://www.ukclimbing.com/articles/page.php?id=8792
Abseil knots
Re: Abseil knots
I was shocked by how weak an overhand knot is when poorly tied too
Backs up the advice of the instructor on this summer's Alpine Training course that you should always 'dress' (ie. tidy up) knots on ab ropes.
Backs up the advice of the instructor on this summer's Alpine Training course that you should always 'dress' (ie. tidy up) knots on ab ropes.
Re: Abseil knots
Same here Cath - also the need to tighten all four stands separately.
One thing I'm not sure about is the comment that you should leave 30cm tails when using an overhand knot - the MI/SPA handbook states tails of at least 60cm are needed (although this does increase the risk of accidentally threading the tails through your belay device).
One thing I'm not sure about is the comment that you should leave 30cm tails when using an overhand knot - the MI/SPA handbook states tails of at least 60cm are needed (although this does increase the risk of accidentally threading the tails through your belay device).
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Re: Abseil knots
(my emphasis)Jack wrote:Which knots do I personally use? For normal abseiling, if the ropes are dry then I use a well-tied, neat, single overhand knot with ample tails (30cm). If I was double loading the ropes with 2 people at once, or if the ropes were icy, I use a double overhand knot. And if I am tying a permanent loop such as a thread or prussik I use a double fisherman's.
Jack also quotes from a documented Needlesports test:
So as long as your "ample" is bigger than the slippage, and 30>7cm. But introducing extra length into the tails increases other risks at the cost of mitigating against slippage. Those other risks including threading the tails, the tails getting caught in a flake, risks of retrieving a rope, pulling down loose blocks, etc.Jack wrote:Due to its propensity to slip on icy ropes (up to 7cm in one test)
Personally, my "ample" is somewhere between 30-60cm: for me, this is my balance or comfort zone between many risks. The balance of risks changes depending on the conditions, crag, weather and my partner gets a say too! Given the choice I will often walk round/down to avoid the abseil altogether.
Re: Abseil knots
That article seems to use quite a few words to say "use a well dressed overhand knot with a second overhand tied immediately behind it".