Abseil knots

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Kev
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Abseil knots

Post by Kev »

Worth a read. Note how weak a figure of eight can be for joining ropes...

http://www.ukclimbing.com/articles/page.php?id=8792
CathS
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Re: Abseil knots

Post by CathS »

I was shocked by how weak an overhand knot is when poorly tied too :shock:

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.
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Kev
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Re: Abseil knots

Post by Kev »

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).
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SteveM
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Re: Abseil knots

Post by SteveM »

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.
(my emphasis)
Jack also quotes from a documented Needlesports test:
Jack wrote:Due to its propensity to slip on icy ropes (up to 7cm in one 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.

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.
Will Hunt
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Re: Abseil knots

Post by Will Hunt »

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".
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