In reply to brt:
> (In reply to Gordon Stainforth)
>
> Interesting re: the double sheet bend and SRT. Could you explain please. Love knot theory.
>
This is my favoured knot for the main anchor sling when the belay is a long way back from the edge when you want to set up a static line: eg. if you want to fix a line to the right of Darius for taking pictures at High Tor at Matlock. You will then use that huge tree which must be 30 ft or so back from the edge, and make a giant sling from a climbing rope, or preferably a static line.
First step is to set up the anchor: a big tape sling round the tree with a large maillon. Next, the extension loop. Lay out enough rope, plus, on the ground, to make the sling. At the point of the loop near the belay, tie a figure-of-nine (the most shock absorbent knot there is) and clip into the anchor. Then go to edge of crag and make the loop, using the double sheet bend. The beauty of this knot is that you can have it right near the edge where you want it and get the length of the loop exactly right, being able to adjust it very easily. (But there's a bit of a trick to this if you're really paranoid, because you'll want to make the loop oversize by an exact amount, so you can then tie another figure-of-nine at this crag end also. Do you follow? - in case, for any bizarre reason the sheetbend fails, or the anchor fails on one side, it will still hold on the other side.) You'll then clip another maillon or big steel D screw into this new, edge-of-crag anchor, and then clip the static line and an ordinary climbing rope as a safety line into that - both with figure-of-nines.
Next you'll abseil over the edge, with a shunt on the safety line, and put a rope protector round the static line at the edge of the crag as you go. Resting on the shunt, you'll then put loop/s with Alpine Butterfly/ies in the static line and arrange extra bombproof nut belay/s below the crag edge (this as protection against farmers or tourists armed with machetes, or a nylon-hungry rottweilers, who will want to destroy your main belay loop ... you really do have to think of all eventualities
Why? Brothersoulshine put it well last night in answer to the question: 'What makes life worth living?' - 'The not being dead bit.'
Why the Alpine Butterfly? Well, again it's
quite easy to adjust, once you've got the knack, and the main force on the rope runs right through the middle of the knot (I think it's almost unique in that respect).