Seems like I heard somewhere that dead pig carcasses were
used for just this sort of test somewhere, but the details elude
me. That should give a pretty realistic assessment of the dynamics
of the system, if you could get a pig into an appropriate harness.
Mark
At 01:12 PM 2/4/2011, Mixon Bill wrote:
The concept of fall factor in assessing the load on belays can be
overdone. Yes, it is probably meaningful when one is talking about a
fall of 40 feet on 20 feet of rope (which would be fall factor 2, if I
understand it). But there is a problem when discussing very short
falls, like 2 feet on a 1-foot cowstail. No matter how static the
cowstail might be, there is enough give in your harness and your body
to prevent the sudden stop that is the basis of worrying about fall
factors. I'd like to see a figure for the peak stress put on a short
length of static rope (it could even be a steel cable for the
experiment) by a caver falling 2 or 3 feet in his harness--not a
theoretical figure, but rather a dynomometer reading. (But even that
would hurt....) It would be a lot different from that of a concrete
block of the same weight attacted rigidly to the cable. Basically, if
you fall 1 or 2 times the length of your cowstail, your harness and
your butt are the dynamic protection.
For a long drop, like a fall of a lead climber from above his last
belay point, the slop available in harness stretch and body
compression is a lot smaller fraction of the fall distance and
provides less protection. In such a case, the stretch of the rope is
critical to avoid death. -- Mixon
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