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Prussik vs Climb Line Diameter

lxskllr

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My very first time trying to rope climb I sent a line up in one of my walnuts, and my goal was to get ~12' up, cut off a dead limb with my Silky, and come back down. Since I didn't have a cambium saver, I tried using the doubled rope(12mm) as a single line with a prussik(8mm) attached to my saddle, and footlocking up. After testing the prussik, it jammed tight, and was very difficult to release. I never got off the ground. I tried the traditional prussik(My preference. I've used it for years for non-climbing use), a Blakes hitch, and a Klemheist. All locked up tight on the doubled climb line.

Question...

It recently occurred to me that the problem might be a function of diameter conflict. Typically a prussik is 50%-70% of the climb line diameter. Using a doubled rope, that effectively doubled the diameter, and caused the prussik to bind?

Bonus question...

I saw a reference to using the tail of the fixed end as a hitch on the free end of the climb line. I gave it a quick try using a Blakes hitch, but I didn't like it. It didn't seem grabby enough. I didn't have it dressed perfectly, but I wasn't feeling confident in it, so I went to my traditional prussik which worked perfectly. Was it completely my fault it wasn't working properly, or is a split tail better/more reliable?
 

Altissimus

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Welcome to the house , in it's simplest bestest form try double lining using the taut line hitch ... Old school proven , safe , effective and it never fails. Mebbee Butch will post his famous pic.
 

Altissimus

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Word Butch ! , all the same rope , all the same diameter. (P.S. I would Neva use a Prussik for decsending , lockup being the reason)
 

lxskllr

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Never tried the tautline. I've used it before for tensioning tent lines and such, but never considered it for climbing. I'll give it a shot next time; maybe tomorrow. That same willow I took a limb off of has another limb that's broken and hung up in the tree. Tomorrow's supposed to relatively cool for MD summer. I might take my climbing gear to work. That, or take my new 661 and start slabbing that ash log. Decisions decisions...
 

lxskllr

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I didn't on the willow, but I like *my* trees :^P

Not completely true. I like all trees, but the willow is low value, and fairly durable. I did try my homemade cambium saver, but it didn't work. It was a 3' length of 1" plastic well pipe. It had a couple potential failure points I foresaw, and the one that got me was it slid out of the crotch due to being too stiff. I cut some hacksaw kerfs in it to give it a bit more flex, and I'll try it again next time. If that fails, I'll widen the cuts to chainsaw kerfs and try it one last time. After that, I guess I'll just have to get something made for the job.
 

Altissimus

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You won't hurt a Willow or any other trees with one time double line access's , just my opinion ... Single line it and you can throw out your savers
 

Mick!

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I only use them on a bigger technical job.

Re. Ixskllr, this guy is starting from zero, no idea whatsoever, isn’t there some video where the bare bones basics are explained?
 

lxskllr

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I wouldn't say "no idea whatsoever", but virtually zero experience. I have a couple books, and have watched videos when I wanted clarification on something, but I'm not a big fan of video. When I want to do something, I go out and try it. If it doesn't work, I figure out what I did wrong, and try it again. In this case, I haven't exactly figured out what went wrong on attempt #1 with a prussik around two pieces of line. Doubt I'll try it again to get something done(especially considering it sounds like cambium savers are optional), but if my bag of rope pieces has some shorter 1/2" line, I might make up a prussik, and see if it still binds on a doubled line. There may be some other physics going on I don't understand.
 

flushcut

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It's a good beginner reference the guy focuses on just the basics: Blakes, throwball, and backing up the system.
 

theTreeSpyder

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To me, a prussic feeds 2 legs of pull of 1/2 bodyweight each, onto line that is pulled harder by full bodyweight>> thus harder to grip
.
So prefer the 50-75% diameter prussic cord formulae to give less footprint for harder pressure in that footprint
>>and to same theory a harder layed cord design than lifeline.>>more grip on higher tensioned line by lesser tensioned line.
.
By doubling line have affected this some, now 2 legs of lifeline each loaded 1/2 bodyweight, but should be doable thru 'tuning' to your style and materials etc., perhaps different cord.
.
Can skip the doubled line and make running bowline; eye retrieved by other line or throw line.
i would climb SRT like this, then pull Bowline open down to self with the pre-set rig line in eye.
>>Switch over to DdRT for work and descent.
i think DdRT is safer to start on, understand more, have 2:1 over own bodyweight, and 2x drop has to funnel thru hitch to fall.
.
Hitches slide easier in DdRT cuz when pull down on hitch, is like rope is failing, and bodyWeight auto shifts to other leg of line
>>unloaded hitch of property type etc. slides easier and catches loaded
>>once again if tuned right to you etc.
.
 

Jonny

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My very first time trying to rope climb I sent a line up in one of my walnuts, and my goal was to get ~12' up, cut off a dead limb with my Silky, and come back down. Since I didn't have a cambium saver, I tried using the doubled rope(12mm) as a single line with a prussik(8mm) attached to my saddle, and footlocking up. After testing the prussik, it jammed tight, and was very difficult to release. I never got off the ground. I tried the traditional prussik(My preference. I've used it for years for non-climbing use), a Blakes hitch, and a Klemheist. All locked up tight on the doubled climb line.

Question...

It recently occurred to me that the problem might be a function of diameter conflict. Typically a prussik is 50%-70% of the climb line diameter. Using a doubled rope, that effectively doubled the diameter, and caused the prussik to bind?

Bonus question...

I saw a reference to using the tail of the fixed end as a hitch on the free end of the climb line. I gave it a quick try using a Blakes hitch, but I didn't like it. It didn't seem grabby enough. I didn't have it dressed perfectly, but I wasn't feeling confident in it, so I went to my traditional prussik which worked perfectly. Was it completely my fault it wasn't working properly, or is a split tail better/more reliable?
I’m not sure you’re doing it right from your description.
You have a rope over a crotch then what? Are you tying a prussik/ hitch around the doubled rope and trying to ascend/ descend on it? Or do you have an end of the rope secured to your harness and the prussik/ hitch tied on the rope on the other side of the crotch?

Is the rope stationary or is it moving through the crotch?

The first way, you could footlock up it, but you won’t get down without more friction from a figure 8 or something like that.
The other way is doubled rope technique aka moving rope.
 

lxskllr

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My first attempt was a static rope. Rope looped over a crotch, with both sides bound with a prussik attached to my saddle. My intent was to footlock up, and advance the prussik. The reason I did that was I didn't want to burn my tree, and I was just playing. There wasn't any good reason to be in the tree aside from trying the ropes.

The successful climb was with a moving rope over a crotch. The fixed end was attached to my saddle, and a prussik attached to the free end, and to my saddle.
 

SeanKroll

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People don't descend on a prussic from a footlock. They use a Figure-8 or the like, after Tying in Twice, and slacking the ascent system. A munter hitch above the prussic would work.

Homemade versions of Rope Wrenches, for SRT, are possible. Kevin Bingham used a stick with holes, as did I, following his lead.

A little more gear, and a lot more function.

There might be good, used gear from folks here. Ask about what you need, before ordering new, if you like.



Good, descriptive thread title...they help a lot.
 

theTreeSpyder

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Feb 12, 2016
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Should not climb to TiP(Tie in Point) with line draped over support limb to prussic both legs as 1
>>cuz the line spread near top draws open hitch.
>>hitch should hold, but when unloaded release with thumb action, then re-grip on command.
The 'choked' Bowline wrote about earlier, does afford climbing to TiP, but more bounce, than doubled line.
.
i like preset friction hitch at right angle, then reverse direction, then lay down to intended direction.
>>The hitch needs to be unloaded to slide
>>Common tie to saddle, then over support then back to friction hitch slider on tail on saddle shifts load to the 'solid' leg when hitch pulled like a failing line on the dynamic side of the rig to afford the unloading of the hitch to slide. Many here started out like this, can go up or down on this rig. Other stuff like you are doing have to swap over to other strategy to descend as stated.
.
You can easily end up in totally preventable bad shituation possibly crippling or killing self; helplessly trapped in dangerous new land with clock ticking, just like novice scuba diver! This is stuff you have someone check out 1on1 and get more than a weekend grip to really be anywhere with it that counts. The above TiP scenario is 1 example, also is having 2 methods of attachment in failsafe fashion, as seen in many disciplines. Living long enough to tell the nurse you saw it on the internet won't impress her!
 

Brocky

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Michigan
Perhaps the not so grippy Blake’s you mentioned in your first post is actually the way a good functioning friction hitch is suppose to work? As long as the hitch grabs immediately when weighted and holds, and doesn’t slip when bounced on, it is considered a workable friction hitch. Not many friction hitches can be used to descend on a fixed rope, if that was the type of binding you were experiencing with the doubled rope.
 

lxskllr

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MD USA
The Blakes wouldn't hold at all. Like I said, I didn't have it properly dressed, so it could have been me, but it didn't want to grab a bit. The prussik OTOH, you can slop it on, and it wants to grab. I really like the plain old prussik. It can barely be considered tying, and it's easy to dress and check for correctness. Biggest downside is it uses twice as much rope.

When my hitches were jamming, it took about everything I had to get them to slide. I might have been able to get up the tree with an angry pack of wolves as motivation, but if I had to do it for a day's work, I wouldn't have made it to the mid morning coffee break. The easiest to manipulate was the traditional prussik, cause the way I tie it, I leave the knot over the wraps. I could take my thumb, and loosen the hitch by pressing back against the knot. Still kind of tricky since I had to hold myself in position using arm and/or leg strength while I fiddled with the knot.

I do want to try the blakes and the tautline using my tail. It works for other people, so it should work for me. Not sure I'd switch from using a split tail, but it would simplify my saddle setup.
 

theTreeSpyder

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i'm thinking Prussic should be more properly a percentage of host line diameter diff. rather than a set amount.
>>i go with 50-75% >> but will try to find real research number.
>>i go with model of want a harder lay and smaller diameter to give a harder package that the 2legs are pulled at half the tension of the line host life line trying to grip/dent
So that hardness is key and line manufacture, loading and smaller footprint of loading in combinations can give this harder surface, even if less loaded, controlling the softer.
.
Try to find where you are at:
Blake's is a single leg of line loading(vs. Prussic splits same load to 2 legs to grip a greater line tension)
>> so would decrease Prussic cord size as a ratio, but more match host line diameter with Blake's as friction hitch strategy to grab a matching line tension i think is essential
>>if done in the BASIC tree climbing style of terminate rope at saddle, then rope over support and back to saddle thru friction hitch should work
>>Blakes tensions are half that of climber as load, BUT Blake's tension will match that of the 'dynamic side of the line that it grips that is also half loaded
Tautline is similar mechanic of matching diameter line pulled by 1 leg, biting into a matching host leg of loading, hardness and diameter amounts
>>MB's pic is of 1 over 2, would start on 2 over 2 Tautline Hitch setup tree to saddle as described
.
Would recommend :Basic start to be on same page
1/2" Arborist Climbing Line w/DBY few feet from end, whereby enough line coming out of short leg of DBY for Blake's back to line after over support.
>>can upgrade to separate piece for Blake's, of same diam. as a wearable item of tail and also unlink to work around objects, reset etc.
>>small krab etc. under hitch for easier tending upwards
>>you note 12mm, close to 1/2" fairly, but suspect mountain/rescue line that is MUCH more elastic; and as i remember (30yr.ago) these knots don't seat same etc. to these purposes.
>>more akin to your footlock prussic setup, but the excess stretch and bounce undesire-able.
(At least that is what i remember of those ropes at that time)
.
Should always have lanyard, especially if repositioning support or doing any work aloft etc.
Then maybe move up to Prussic on SRT as are doing after the DdRT(Single and doubled Rope Technique) is comfy
>>What you are doing on folded line is differentiated as DRT for 2 legs used as 1 SRT
 
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