Speleotron said:I always thought that anything which might involve falling onto a jammer is dodgy; why you wouldn't just use an italian hitch?
Speleotron said:Yes I meant for belaying/lifelining not z-rigging or hauling etc. And you can make the italian hitch auto-locking as well https://andy-kirkpatrick.com/cragmanship/view/locking_munter
Bob Mehew said:The report of the work on which the notice was based can be downloaded from https://drive.google.com/file/d/1XLZyRdMzNjlnUar5LA0r_rVk-nqfLu2F/view?usp=sharing . No doubt, BCA's E&T, QMC and Training committees will issue minutes in due course covering their deliberations.
Two asides: I would observe that the terms belaying / lifelining / progress capture / hauling etc seem to me to be splitting hairs and fundamentally are covering the same task with the same potential fault scenarios; and that a person falling even short distances on low stretch (SRT / semi static) rope can be seriously hurt.
droid said:Was that Garlands? 15 foot pitch, usually taken far too lightly. Gets VERY wet.
The location of the load cell does not influence the force seen by it, see page 6 in http://www.roperesearch.co.uk/pdfs/the%20rig%20v2.PDF . It only affects the timing of when the force is seen. (http://www.roperesearch.co.uk/index.html provides more detailed information on the rig.)mikem said:The only question I have is where was the load cell located? As force on climber will not be the same as force on pulley (the easiest place to locate the cell).
In which case the full load will go onto the jammer, so the effective force on the climber will be higher (you're probably better off damaging the pulley!)Antwan said:If you do have to haul with that specific equipment the jammer should be on the other side :spank:
What is your evidence for this statement? It is not force that is dissipated, it is energy.mikem said:But even if you assume that there is zero extension in the low stretch rope, the 6.7kN recorded by the load cell has also been dissipated into bending the pulley and stripping the rope, so won't be equal to that experienced by the climber...
The point you miss is that the belayer will have a bigger effect in reducing the peak forces seen by the system since their body is not as resilient as the steel. (The report touches on this point.) The feature of the system we are discussing (pulley and toothed jammer) is that there is no equivalent human body, just steel. If you look at the detail you will see that the peak force in the simpler set up of just a toothed jammer is higher (10 BPC 40) than for pulley and toothed jammer (12 or 20 BPC 40).mikem said:Climbing walls are now using semi-static ropes for top roping, but they will always have at least the full length of the climb between the belayer & climber (so still a reasonable amount of rope to minimise the fall factor), whilst a caver slipping at the top of the pitch will have hardly any rope between them - should we still be advocating dynamic rope, or is the effective distance so short that it will make hardly any difference?
andrewmc said:The rule is simple.
Don't belay with your teeth, or anyone or anything else's.
mikem said:Energy = Force x distance, so if energy is lost in the deformation of the pulley, but distance remains the same, the force must surely also reduce...