The Frog System
by Peter Penczer
In November 2000 I spent two weeks caving in France, where I learned some
valuable tips about the frog system. I have been using this system for about
six years, and I always thought that it was inefficient. In reality, it was
only my frog system that was inefficient.
Naturally, the French donít call it the frog system, any more than they refer to French fries as French fries. Itís the only system they have for climbing a rope, and as best I could determine, there is no French term for vertical gear. The rigging, anchors, and climbing gear are part of one integrated system for tackling vertical caves. Everyone in France goes vertical caving the same way, so they know their system very well. Here are a few things I learned:
The chest harness is critical for climbing efficiently. French caver JoŽl Raimbourg showed me how to make a simple chest harness that makes climbing much easier. It supports some of the weight of my upper body, holding it close to the Petzl Croll and saving me from doing a pull-up with every climbing stroke. To make the harness, tie a piece of one-inch webbing into a loop 34 inches long (I am about five feet and ten inches tall). Twist it once into a figure-eight, and put one arm into each loop. Grab the part of the loop where the webbing crosses itself and pull it over and behind your head, onto your back. Next, grasp the two pieces of webbing that cross your shoulders and pull them together and clip them into your Croll with a small carabiner. Use the type of íbiner that is intended to be used as a key chain. A full-sized carabiner is too large and will make your system less efficient.
The chest harness should be so tight that you canít stand up straight when youíre not on rope. I clip the two shoulder loops together with the small carabiner and wait until my Croll is on the rope to clip the íbiner into the Croll.
If you donít understand this description, look at the drawings on page 7 of the book Vertical by Alan Warild. In Europe, you can buy a ready-made frog chest harness that looks like a ropewalker chest harness without the roller. Several varieties can be found in the Expť catalog (the biggest speleovender in France), and might be available from American speleovenders as well. I used to use a Petzl Torse, and it made for very inefficient climbing.
The seat harness leg-loops should be tight. This is not important with a ropewalker, but very important with the frog. If there is two inches of slack in your leg loops, your body will drop two extra inches every time you sit down on your Croll, which you do with every climbing stroke.
Keep your foot loop short. A foot loop that is too long will make it difficult to pass rebelays. Moreover, when you are climbing, your arms will be stretched out above your head when you start the motion of standing on your foot loop. When you stand up, youíre trying to hold your upper body close to the rope, and if your arms are above your head, you wonít have much leverage. Thatís not very efficient.
To be sure your foot loop is the proper length, get on rope and stand up straight in your foot loop with both feet. Your Croll and the ascender on your foot loop should touch. I use a handled ascender (a Petzl Expedition) on my foot loop, but I find it easier to climb if I hold the frame of the ascender near where it contacts the rope, rather than holding the handle. JoŽl said some French cavers use a Petzl Basic on their foot loop to save weight.
The following tips are more for safety than efficiency:
Close the gates on your ascenders. The gate on your Croll is not all that strong. If you leave it open as you pass through the cave, it might catch on something and get damaged.
The D-link should be properly oriented. The gate should be on your left. If the opening is on the right, the movement of the rope as you are climbing will unscrew the gate, leaving the D-link open. This happened to me twice before I realized what the problem was.
For more information see:
Warild, Alan. Vertical. Broadway, NSW, Australia: Speleological Research Council, 1994. A good book on vertical caving techniques, with both European and American styles covered. Available from the NSS bookstore and other speleovenders.
<http://nerve-net.zocalo.com/jg/c/tech/> . John Ganterís website has an excellent article by Matt Oliphant on configuring and using the frog system, with some additional notes by Ganter.