To answer: > Free fall is possible at an overhung rebelay, but you are correct that > testing cows tails with a rigid weight is wrong.
I personally think that whereas it could be considered wrong to test cow's tails with a rigid weight it does give a worst case senario, if the cow's tail gonna fail then you really don't want to be using it. Consider it this way: if you, in your flexible body/harness, fall on a cow's tail in a worst-case senario (free fall) you want it to hold don't you? Would you rather be hurt and suspended, or dead on the cave floor? I also don't agree that the cow's tails can be considered static, made of dynamic rope there is some stretch inherent in there, more than a static/web harness. Cheers, Stefan ________________________________ From: Minton, Mark [mailto:mmin...@nmhu.edu] Sent: Friday, October 17, 2008 1:01 PM To: nmcaver; txcaver Cc: Ralph Hartley Subject: [Texascavers] Re: Cow's Tail Tests FYI Below are some comments on the cow's tails test that I mentioned recently. Mark Minton ________________________________ From: Ralph Hartley Sent: Fri 10/17/2008 11:58 AM To: bob.th...@md.net Cc: mmin...@nmhu.edu; nmcaver; txcaver; gvks Subject: Re: (GVKS) - Re: Cow's Tail Tests Bob Thrun wrote: > Mark Minton Wrote: >> Extensive tests on various types of cow's tails have been published >> at <http://british-caving.org.uk/rope/lanyard_tests_v6.pdf>. > > Unrealistic tests with free fall and .a rigid weight loaded in line. > Most rebelays are near a wall, so no free fall. The tests detected > the slight slippage of knots being tightened. the human body has more > give than the knots. Free fall is possible at an overhung rebelay, but you are correct that testing cows tails with a rigid weight is wrong. -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
