Cave_Troll
Active member
1) rope strength:
new rope has a strength of about 30kN
Tie in a knot (60%) - 18kN
10:1 safety margin is 1.8kN = 180Kg
ie in an emergency , rescue, hauling or mid rope rescue situation, with two slightly large cavers, you are eroding into your safety margin and hope that you don't shock load the rope.
2) cavers butterflies.
I've just tied one on a bit of rope on my desk. Set it and pulled it tight all three ways.
I then undid it by repeatidly flexing the knot , pushing the rope in, from either side. This is not a good idea and is the reason you always tie a stopper knot on a bowline (unless its in the middle of the rope)
Be aware of this knots limitations. Any cavers i teach are taught to avoid it like the plague.
new rope has a strength of about 30kN
Tie in a knot (60%) - 18kN
10:1 safety margin is 1.8kN = 180Kg
ie in an emergency , rescue, hauling or mid rope rescue situation, with two slightly large cavers, you are eroding into your safety margin and hope that you don't shock load the rope.
2) cavers butterflies.
I've just tied one on a bit of rope on my desk. Set it and pulled it tight all three ways.
I then undid it by repeatidly flexing the knot , pushing the rope in, from either side. This is not a good idea and is the reason you always tie a stopper knot on a bowline (unless its in the middle of the rope)
Be aware of this knots limitations. Any cavers i teach are taught to avoid it like the plague.