WHAT?!


quote:
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Originally posted by Tom Dunlap
Also, since the weight of the rope below the rack will have a big effect on the rate of descent, it adds another reversal into the formula.
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Icabod said:
"Tom, I almost always agree with your posts, but this time you threw me. The rope is supported by the tie in point. The only load on the rack is the climber and the gear he carries. The rate of descent is controled only by the number of bars the rope travels by. "

Nope, Tom is right. The weight of the rope itself below you is a big factor...it acts similar to your hand pulling down the rope and locks off devices. The climber's weight is supported by the anchor, and to control the rope you have to control the weight of the rope beneath you.
On a long drop you actually have to feed the rope up into the device to get it to let you free.

On a similar note, I've been climbing in some eucalyptus trees with a 60 meter/200 foot rope (which isnt enough to get you back to the ground in several of these trees.) The weight of the rope itself is so strong it will zip on right through the pulley and friction knot- you have to be vigilant otherwise, when not tied in, it will try to escape you!
A local arborist, Jerry Romanski, uses a second prussik loop far beneath to take some of the weight on his harness...I've just been using alpine butterflies to give me some slack to work with. I'd like to just use a shorter rope, butcant bring myself to use the knife...