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General Climbing Discussion

Topic Date User

tyrolean traverse 20-Nov-2011 At 5:39:10 PM Paul

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On 20/11/2011 lacto wrote:
>from pauls post if you only want a safety factor or 10 % your are crazy

Probably not the clearest explanation on my part, by 10% I ment putting no more than 10% of the weakest point of the system, so a safety factor of 10 or 10% safe working load, not a 10% safey margain. 10% safety margain would be very scary.

> 200 to 300 % would be better as failure is you DEAD or MANGLED . the crabs
>you use are 20+kN but 1.1 kN would be a 10% safety factor so you have a
>sf of 20+ with a normal crab
>Also paul is out in his forces on the rope actually 100 Kg and 10 derees
>of sag ( and the centre point of the rope will give the largest load of
>the rope is
>100/2*9.81/ sin 10 =2.86 kN in the rope both in tension from the centre
>point and hence will load each anchor point with 2.86 Kn in the direction
>of the rope .

Your calculations are based on 10% sag, or an included angle of 160 deg when the pulley is in the centre of the tyrolean, my calculations were were based on 5 deg sag with the included angle of 170 degrees. both our calculations are correct although mine not explained as clearly.

the main point is the tighter the rope the bigger the forces.

Putting weight on an ascender wont increase the loading at
>all as the weight that goes on the ascender is removed from the load you
>have from your harness.

The ascender will create an increase in pressure where it is located on the rope similar to the rope running over an edge of a cliff. Not sure how big this would be or if it would be a issue, but ropes are more subject to damage while under tension.

>Can't emphasise enough that large safety margins are sensible and 2 ropes
>or more even more sensible . Be absolutely sure within yourself that your
>setup is good before you launch.

Very good advice, also ensure that your ropes are sharing the load evenly between them and both have redundancy independant of each other.