Saturday, November 04, 2006

Film Festival, Ice Book Correction.

As walked into the film maker's seminar yesterday I found the way forward blocked by a crush of people along the path. You spend a lot of time at the Banff Festivals slowly moving forward through throngs of people, it's just how it is, so I slowed to a shuffle and couldn't help but over-hear a conversation about Andy Kirkpatrick's slide show the previous night. It went something like this:

Head Scarf: "I saw that young British man last night, he had some nice stories but it doesn't sound like he enjoys climbing very much."

Large Garments: "Yes, it did seem a bit unhealthy. And such a pity about the language he used, it was almost intolerable."

Head Scarf: "I really wish he wouldn't use such blue language, it took away from his nice presentation."

Andy had shown pictures from some of the worst sufferfests I'd ever seen, and all these women remembered was the language? I think Andy would be dissapointed... If you're bored check out Andy's site--I felt much better about my own obsession with climbing and flying after reading the articles on his site, I'm almost normal in comparison. Great site!

One of the best parts about writing a book that people really read is that they send you emails helpfully pointing out mistakes. Grin. Seriously, I do like getting the emails and a guy down in Colorado found a really good error in my Ice and Mixed book. Here's a quote from our email exchange:

Colorado Guy:
pp. 179-180: The caption of Figure 13a says that clipping at waist level "reduces the distance of any potential fall." This is a bit misleading. The distance, for both Figure 12a and Figure 13a is twice the distance between the last two anchors, plus rope stretch. It is true that in Figure 13a the climber falls with more rope out and therefore has more stretch, but the main reason for preferring Figure 13a is that the starting point of the fall is farther from the deck. If the deck is far away, clipping high actually provides the softer catch in case of a fall.

To which I responded:
"Ah hell, I just spent two hours working through this with paper diagrams to prove that you're wrong, but you're right, grin, good one. There are diagrams spread out all over my desk, my girlfriend Kim got into it too. The overall point of not clipping high overheard when close to the ground "stands" (as I have unfortunately personally tested), but my reasoning was very flawed. I find it very interesting that the total distance fallen when clipping will always be roughly the same, it's the starting point above the ground that so obviously matters. A much more elegant and correct way to state the situation. Counter-intuitive but true. How does the following text sound to clear this up?"


Clipping bolts or other fixed gear while still close to the ground can be dangerous; if you fall while clipping you may hit the ground. Interestingly, it's often safer to clip the first few bolts while your harness is level with the bolt rather than reaching overhead to clip the rope in. This seems counter-intuitive, but here's how it works. First, if you're clipping over-head you'll generally put more outward force on the pick as you reach up, which often causes the pick to skate out and off the placement. Second, the total fall while clipping a bolt is always roughly equal to twice the distance between the last clipped bolt and the bolt you're clipping (plus rope stretch). If you fall off while clipping a bolt above your head you're more likely to hit the ground because you're closer to it and have less vertical space to fall. If you blow a clip while clipping with your waist close to the bolt you'll still fall the same total distance, but because you started the fall higher you'll hopefully end up with your feet still above the ground. If you have a bomber hook then clipping overheard is often worthwhile, but if the climbing is tenuous wait to clip until your harness is level with the bolt."

I'll work on the above a bit, but do you think it more accurately states the reality of falling off while clipping? I have to keep the total words nearly the same for the next printing.

The point about making sketchy clips with your harness next to the bolt is still valid and the illustrations in the book are still accurate, but I got it right for the wrong reasons. If you can't figure this out take some graph paper and draw situations where the climber falls off while clipping overhead and while clipping with the bolt at waist-level, it simpifies things when the rope and placements are all to scale. Having 10 total feet of rope pulled out to clip two bolts ten feet apart will result in a 20-foot fall; clipping the same bolt with your harness knot exactly beside the biner will also result in a 20-foot fall, you'll just end up higher above the ground. Bizzare but true, I only burned about ten pieces of graph paper to figure it out, it will likely take smarter readers less graph paper. A corollary to all of this is that blowing an overhead clip while high on a route actually provides a slightly softer (same distance though) fall...

The writer also had another good point: Many climbers assume that a half rope system with one strand clipped into a piece (as it should be unless both ropes are clipped into all pieces) will result in a lower force fall than one taken on a "single" rope. I've heard this stated often as a good argument for using half ropes for ice climbing--seems logical to reduce fall forces on ice screws, so half ropes are "better." I never questioned the basic belief that a half rope provides lower force falls--you can just look at the impact force chart's on BD's website, it's obvious. Actually, it's not, the weights used to test impact forces are totally different, I just never really thought this through... I'm now not so sure what to think, more research is required.

So thanks to the writer from Boulder for pointing all of this out, it's interesting.


1 comment:

sam said...

I got to thinking about your description of falls taken while clipping. I think it might be easier to understand if you stated that when you fall clipping you will fall x distance regardless of your position. But by starting x higher you end up further off the deck.

I found this interesting to think about because as you mentioned not many people are aware that the total fall distance remains about the same.

To make it clearer you might add length indicators on the rope in the picture.

Great book by the way, I learned a great deal from it and more each time I go back to it.