After scanning through this report it doesn't appear that static rope cowstails were tested ... all of the knotted cowstails were various types of dynamic rope. I think this supports my earlier claim that the use of dynamic rope for cowstails is "standard practice".
SDcaver wrote:"One of the lessons from this series of tests is that the theory behind Fall Factors inadequately
explains how shock loads are absorbed by Cow' Tails. In particular it is the knots that absorb the
greater part of the energy from a fall and in various identical set-ups, it has been demonstrated that
the shock loads are inversely proportional to the fall factors (see p. 3213).
I believe the second sentence is a mistake. The data they collected clearly shows a direct, not inverse, relationship between shock load and fall factor. I'm also not sure about the validity of the first sentence. They do demonstrate that the use of knots reduces shock load over sewn terminations, but I don't see any data that shows how much of the impact force is absorbed by the rope vs. the knots. Perhaps if they measured the shock load using a steel cable then we could make a better comparison.
"Despite this we should continue to teach that cavers should not position themselves above their anchor point when using
Cow's tails; fortunately this is a situation which is quite easy to identify.
Hopefully the general idea of minimizing fall factor exposure is well understood by both cavers and climbers. Perhaps it can generally be stated that reducing your potential fall factor, using knotted rather than sewn terminations, and using dynamic rather than static rope are all strategies for reducing shock load forces in the event of a fall. In the example of the Rift in Lechuguilla it is common that the D maillon is above the rope on many parts of the traverse. Ideally you should always be below your anchor, but in practice there are sometimes exceptions.
Dynamic rope is designed to stretch over length, and 10-14 inches is not much length (well, depends on what we are talking about
)
My cowstails are a bit longer than that. Still, cowstails aren't very long, but then the potential fall distances aren't very great either. It's all relative. I trust 40' of dynamic rope to catch a 20' leader fall just the same as I trust a 2' dynamic cowstail to catch a 1' fall in a cave.
Also I find it interesting that Petzl makes a sewn static cowstail, which preforms the worst in all tests. Yet, where are the lawsuits involving injuries or worse due to their correct use?
I argue above that I use my cowstails for fall protection, and I think a great many other cavers do the same, but I suspect cowstails are very rarely called upon to catch a fall, and when they do it's probably a very low fall factor. I've been ice climbing for 16 years and never taken a leader fall. In theory I could have done all that climbing with a static lead rope, or no rope at all, and the results would have been the same. I'm not sure that's evidence that static ropes are safe for leading ice.