July 1999 - Tech Tip Supplement
Ever wonder about those one-way "clutches" such as the Garda knot?
The day following the Rigging for Rescue course we had the opportunity
to test things (i.e. break things) on their drop tower and slow pull
machine. Very interesting and, at times, entertaining.
We slow pulled a Garda hitch and a Staufhauser (sp?) hitch and watched
as they locked off tightly enough for the bowline at the end of the
rope to fail. Most of us would expect some slippage in the hitch rather
than the rope failing at the bowline. So these are good hitches deserving
of some confidence.
I also tested a Gi-Gi, which is a plate type belay device. It is supposedly
useful for belaying two seconds at once, very useful in guiding. While
it shows how one of the climbers can be caught and the other can continue
to climb it does not indicate what happens if both fall. It held as
it should with both one rope pulled or both. This was true in both slow
pulls and a UIAA load drop test. The plate is still intact but it is
time for a new one now.
We tested a large, heavy and expensive industrial device which had
been brought by a couple SAR techs in the Canadian Forces. It failed
on the slow-pull and on a drop test the load went right to the ground.
This thing looks beefy, but appearances can be misleading.
Finally, we tested a new thing by Petzl called a Tibloc. This is a
light, simple, and cheap equivalent to a mechanical ascender. I look
forward to getting one and playing around with it a bit more. They can't
cost too much so you might want to check it out.
These are only a few of the tests done. Eventually I should get the
full data after it has been analyzed and graphed on the computer. I
may post some of the more interesting findings somewhere on my web page.