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Topic Date User

Petzl Pro Traxion Good all round Pulley Choice? 16-Oct-2011 At 9:17:32 PM Rocker

Message

Patto, could you please clarify?

On 16/10/2011 patto wrote:
>
>A quick calculation shows that your assumption is incorrect

F=MxA

>If you assume ZERO SLACK in the rope then the subsequent peak force is
>2x body weight regardless of the elasticity of the rope. Thus the force
>on static and dynamic ropes is the same.

F= 80kg (800nm) climber x 0 Acceleration
Therefore the force (or weight) on the rope is 80kg, how can it be 2x?
Yes, in this instance there would be no difference between ropes.

>As soon as there is slack in the system then the dynamic rope being more
>elastic will give lower peak forces. For the large amount of slack in
>lead falls obviously a dynamic is required to keep peak forces at survivable
>levels.

F= MxA
F= 80kg climber x decceleration from a fall
Therefore a static rope has a higher decceleration resulting in a higherforce produced in a fall.

It would be logical that a dynamic rope would therefore be best used in a self belay... But ive been wrong before!