Chockstone Forum

      Sponsored By
      ROCK
   HARDWARE

Chockstone Photography

Australian Landscape Prints

Chockstone Forum - General Discussion

General Climbing Discussion

Topic Date User

weird ways to get wasted - 1 16-Jul-2003 At 7:18:37 PM (removed)

Message

The overall load isn't reduced by a factor of 5, the peak load is. The energy in the quickdraw system is spread out over a longer period (still instantaneous to us humans) as the quickdraw "stretches" and "retracts". Same philosophy as behind a fall with a dynamic vs static rope, except in this case you can see the difference. The order of magnitude of time taken is something like (and this is why I wish I could find my project) 0.04 secs vs 0.2 secs. Both are too short for us to differentiate with the naked eye.

This was tested at Melbourne Uni eng. department (by me along with some Star Teek geeks, I was in Sci, not Eng) back in Semester 1 1995 (May-ish ??) with static rope (to reduce the number of variables). It came about beause I read it in some magazine and was surprised by the fact that the difference was so high, hence I chose this as my free project (I was also completely obsessed by climbing at the time and therefore would do anything to tie maths back to it.).

You don't have to believe me, and to us a quickdraw does feels "inelastic" - as you say, but what I read and what I tested both agreed with each other. It appears that even the tiniest of elongations serves a dampening purpose in a fall.