by john » Mon Aug 15, 2005 8:23 am
I normally don't bother with these discussions but this one interested me for many reasons. A few corrections so misinformation doesn't multiply.
1) dcentral:
A gri gri on the floor is not the same as directly off the anchor, since at BG it is attached at the floor then goes up to the roof, allowing rope stretch and force dissapation (25ft?) in the event of a TR fall and is then redirected by a biner and more dymanic rope to the climber. Directly off the anchor a gri gri and reverso are both considered a static belay due to their minimal slippage, therefore translating all the fall force minus the rope stretch to the anchor. This is not a problem top roping due to the minimal forces involved assuming you have a safe anchor. Where this can make a difference is in a situation where there might be some accidental slack in your belay, typical if you are standing on a ledge not hanging on the belay. Even slight slack in a static belay, ie. any dynema slings coupled with a static belay device, greatly increases anchor forces even in a small fall (See rock and Ice a few months back for the numbers). So make sure there is no slack at all, and your anchor is safe, if it is queationable and you still want to use a gri gri, put it on your waist and redirect it through the power point with a biner so your body can absorb some of the fall force. If I misunderstood your point sorry.
2) A reverso can be unloaded failrly easily with a bit of practice in almost any situation. As stated it is slightly dependent on the belayers strength vs the climber weight and drag ect. but, mostly dependent on the unloading technique. Here are a few tips that may help when uses in the autoblocking mode.
If the fallen climber is light often even without their help if you pull up on the climbing strand and take the autoblocking biner in your other hand and twist it perendicular to the rope while giving a tug towards the upwards direction along the same path as the fallen climber I have found I can easily unweight the rope, the key is the slight twist to initially unload the camming action.
Secondly as mentioned attaching a sling to the locked biner then standing on it does work although providing a jerkey descent. I have used this to lower much heavier people than myself out over overhangs and on at least 2 occasions.
Third for the fatest of climbers you will need a little trick I have been experimenting with. (Disclaimer use only with solid individual anchor points.) clip the long slind to the locked biner like above, but then clip a biner or quickdraw to a single anchor point well above the reverso. Pass the sling up through the biner and then down to your foot. Then step on that. The reason this works seems to be due to the direction of the forces involved. A loaded reverso pulls the lock biner into the reverso with a slight angle with respect to the diretion of the rope to the fallen climber. By stepping in a sling attached direcctly to this biner it is bending the rope more and if you are not careful it just tightens down on the rope. So either really pay attention to the direction you step with your foot, straight down is not the best or try the redirection. I haven't used this method much, but I thought I would mention it for interest.
cheers