Petzl preliminary research

I'm curious to know whether or not there is a decrease in forces when climbing DDrt using a friction saver versus DDrt natural crotch. Any one have any thoughts or insight on this one?
Just curious, thanks
 
How come I am qualified to judge which crotches will hold double loads in rigging, where the load is usually far and above ones body weight (and often unknown)t; but I am not allowed to judge whether a crotch will support my (relatively constant) weight?

Life, limb and property are regularly at risk in both cases.
 
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I'm curious to know whether or not there is a decrease in forces when climbing DDrt using a friction saver versus DDrt natural crotch. Any one have any thoughts or insight on this one?
Just curious, thanks

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In DdRT, the less friction, the more efficient the system and the more constant the load is on the TIP.

The concern is that the force generated from a fall, which as the information in the OP reflects, is much greater regardless of the amount of friction at the TIP, given the parameters of the testing. It seems to have most to do with the amount of rope in the system, and the system configuration being single line or doubled line.

At Expo, Rich Hattier was demonstrating a shock absorber that looks a bit like a rope running through a rubber rack. When the rope loads up, the rubber flexes and allows the rope path to straighten, thereby absorbing the shock.
 
I've seen (caused) damage to scots pine several times (I'm a slow learner or perhaps just to optimistic) when climbing up srt. The rope digs right through the bark and cambrium. So pulling up a cambriumsaver has finally been incorperated.
 
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This is interesting

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I'm sorry I missed the discussion this list came from because I'm missing the context.
Kevin I'm glad you named this thread "preliminary research" because this concept is so far from "conclusions".
I think the best that can be hoped for is a better understanding of the variables and the ( excuse the pun) IMPACT of not understanding.
Few random thoughts.
My FIRST choice for an SRT anchor is still a cinched canopy anchor with a screw link. Recoverable from the tree and the ground, no friction, no crotch rubbing (you didn't just think that!) cambium damage, easily changed to DdRT in the tree, 2-3 redirects can be recovered from the ground.
You may have noticed but the zip line we used at the 'vous had a base anchor and a midline attachable leather cambium saver. Worked well with all the repeated activity at that crotch.
Some variables effecting this "preliminary research"
Length of rope in the system.
Stretch of rope used.
Shock absorption characteristic of rope used.
Bounce characteristic of rope used.
Diameter of rope.
Diameter of crotch.
Angle and shape of the crotch.
"V" shape or pinch of the anchor.
Coefficient of friction of of various tree barks.
Coefficient of friction of various rope materials.
Redirects.
Rope construction.
Climbing method used. (Hip thrust vs walker) small steps vs large steps. i.e. Hopping up the stairs vs. smoothly walking up the stairs.
Length of time over which the force is applied to the anchor. Sudden fall vs. stepping on to the system.
Pulleys, RtoR FS, natural.
Wow!!! The list is huge I'm sure.

Here is a good example I had last week
65' anchor, suitable branch high in the canopy but with a small stub preventing my line from setting in the crotch 2' below. Rather than trying to reset it or use various methods to adjust the anchor, I simply cinched it in place for the SRT climb. Had I chosen a base anchor or DdRT it probably would have rolled off or slipped putting a shock load on the anchor and me.
 
At the top of the list for potential tree damage is species. Thin barked trees like sycamore will exfoliate delicate bark right down to the cambium from walking on limbs in the spring.

Next, consider the maturity of the bark at the TIP. Some species, maples for example, have corky bark down low but delicate bark up high. Knowing how to visually ID the difference from the ground is important. This would change a decision to use a false crotch or not.

None of what I said is new to tree climbers. It is something to add into our decision making.
 
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Here is a good example I had last week
65' anchor, suitable branch high in the canopy but with a small stub preventing my line from setting in the crotch 2' below. Rather than trying to reset it or use various methods to adjust the anchor, I simply cinched it in place for the SRT climb. Had I chosen a base anchor or DdRT it probably would have rolled off or slipped putting a shock load on the anchor and me.

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I've had this kind of small TIP blowout happen many times DRT and SRT. I'm sure it's the same for other climbers. In some cases I got a decent bounce out of it but nowhere near anything that was hurting me or my gear. At any rate the long rope length in a base anchored system really softens up the ride when that happens.

As Kevin mentioned, there is considerable absorption happening in the various components in the climber's system. Another reason to love the RW or HH, the hitch absorbs dynamic loading extremely well.

Speaking of which, last winter I was climbing the ZK-2 on a cinched SRT anchor and the cinch slipped down on me (more dynamic force was transmitted to the anchor as I got close to it) and was caught by a substantial crotch approx. 2' below the original anchor. It caused me to utter some choice words but the "landing" was super soft on the wrench. If I was on a toothed cam ascender it would've been a hard bounce.

As I alluded to above, a cinched anchor is great but the closer you get to the anchor the less dynamic the rope becomes.
-AJ
 
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Speaking of which, last winter I was climbing the ZK-2 on a cinch
As I alluded to above, a cinched anchor is great but the closer you get to the anchor the less dynamic the rope becomes.
-AJ

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Good point moss, this is why understanding what is going on becomes so important, so that you can predict the consequences. Good thoughts and discussion.
 
What we're seeing here is something that top rope rock climbers have known for a long time. Since they climb on dynamic/really stretchy ropes if they fall on a low part of the climb there's a good chance that they're going to hit dirt. Getting up a ways reduces the length of the stretch with less rope in the system.
 
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Speaking of which, last winter I was climbing the ZK-2 on a cinched SRT anchor and the cinch slipped down on me (more dynamic force was transmitted to the anchor as I got close to it) .......some choice words but the "landing" was super soft on the wrench. ....
-AJ

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Also moss, if you had a little more of that "pesky" weight like I do, perhaps your cinches would have a little more cinch but then you wouldn't go floating around the tree like you do either.
laugh.gif
 
why is this so special to SRT? its exactly the same with Drt except we have more stretch due to one line.
 
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why is this so special to SRT? its exactly the same with Drt except we have more stretch due to one line.

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It's more special to base tying than SRT I believe. Base ties introduce a lot of line as well as tree into the system
 
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