OpenTrackRacer wrote:Chatting with the guys at REI, one with a lot of climbing experience said he uses a Petzl Shunt (which is basically a mechanical Prusik) with a figure 8 or ATC. I messed with it and then did some more research and it now I'm really glad I went to REI. This device is perfect. It can be used with our current descending gear, it's simple to operate, keeps the hands where they should be and offers a second point of attachment to the rope. As an added bonus, it address the free hand issue since you can move it down the rope and then descend a bit on the ATC (with your other hand on the down rope of course) and use have a hand free for pushing off, etc.
Sometimes you end up with a solution that's completely different from where you started.
Be cautious here - the 8/ATC and Shunt combination may not provide the ideal solution you think it does. By all means try it out under controlled conditions if you can borrow one, and if you really like it then go with it. Some cavers in the past have used a Gibbs or similar mechanical shunt to do basically the same thing, either installed above the descender or below. This is known as the "spelean shunt." Few seem to use this technique any more as it has a major drawback. Once the device locks with your body weight on it, it can often be difficult to transfer your weight so you can release the shunt again.
With no offense to the employees of REI or to climbers in general, the operative term in your post was that a guy with a lot of
climbing experience recommended the Shunt. Although many devices and techniques do overlap between the climbing and caving communities, there are subtle considerations which are not always obvious to climbers. Broad examples include using static vs dynamic ropes of various diameters, muddy/gritty ropes, free hanging ropes, confined spaces, ascent/descent changeovers, rebelays, etc. I personally own a Petzl Shunt, which I've seldom used. It was not purchased for use as a rappel safety for caving.
Tim White wrote:The GriGri does not work well on Pit rope, it's to stiff IMO.
Keep your rope clean and prepare to spend some big $$ for the I'd. This is the most common descending device used by professional rope access technicians. A SOLID piece of equipment, but it would never hold up in a cave environment due to the working mechanisms vs mud.
hank moon wrote:There is only one bobbin I know that works well on PMI 11 mm pit rope: the SRT Stop descender. The Petzl Stop (and others) can be extremely fast or slow on such rope depending on conditions. The Anthron is particularly difficult to use on stiff rope.
The only other self-braking descender I can think of that might work well is the TROLL Pro Allp Tech.
Although I have to say my Petzl Stop usually seems to work OK on PMI 11mm *for me* - your experience may differ. I also have an SRTE Stop which works nicely, but my one is all stainless steel so it's VERY heavy and not my first choice for carrying. The Allp descenders are nice, but like the SRTE they are quite expensive if you can even find them in the US.
If you haven't totally ruled out the Petzl Stop, I found a few old topics you might like to read.
Bobbins and StopsAnyone use a Petzl Stop Descender?Spinoff post about the stop