Friction hitch on double rope

[Tree Machine]

I enjoy seeing stuff like Tod's floating false crotch. I really try to keep the complexity of the climbing system minimized, straight-forward and swift in setup. Tod's rig has lots of parts and pieces and stuff going on. Fascinating.

Back to Mihalek's original question, and the reason I've hung with this thread is because the the basic system he described, ascending two parallel lines and abseiling down those same dual lines is how I've done it my entire climbing career. This doubled rope technique (DbRT) is a 1:1 system which made more sense to me than the 2:1 DdRT. As mentioned earlier the 1:1 DbRT is very similar, almost identical in ascent, as SRT, so moving on to SRT was no stretch. DbRT is still my preferred method, only because it's faster than SRT in that you don't have to take the time to anchor to the base of the tree. If I can isolate the limb or crotch and successfully trace the line back parallel, I climb DbRT. If the trace is taking any time at all, I let the bag drop straight down, anchor it, and climb SRT. It just doesn't matter. They're both 1:1 systems. The rope at the crotch does not move, so there's no friction there, no need for a false crotch. Friction control is on two lines or one line, but handling the friction is very, very much the same whichever way you go.

 

[Tom Dunlap]

TM,

Don't confuse the lingo...DdRT is 'doubled'...

If you want to use D[bee]RT to signify another concept, come up with another name that is significantly different.

The advantage of using agreed upon acronyms is that it makes writing much easier. Your DbRT is so much like SRT that very few people would understand.

 

[Tree Machine]

As I understand it, both DdRT and DbRT are both doubled rope systems. DdRT is the system, traditional tail around standing, or split-tail where the 2:1 mechanics pulls the rope over the tie-in point as you ascend or descend.

DbRT is also a doubled rope system but is 1:1, you're working your way up and down two parallel lines and they dont move back and forth over the tie-in while ascending or descending. The lines don't move vertically relative to one another. Both ends stay on the ground and the rope sits stationary at the tie-in point.

DRT is double rope technique where you are using two seperate ropes. Each of those two can be any one or combination of the three techniques.

I'm not crazy about the nomenclature either, find it confusing which one is the d and which one is the b. I've seen DbRT names static doubled rope, but that can be confused as using a traditional arbo system using a static (as opposed to semi-static or dynamic) rope.


The techniques are distinctly different and I usually describe what I'm talking about in words or pics for the clarification. The thread here is is titled 'Friction hitch on a double rope' but by the opening question it's clear that Mihalek meant to write 'Friction hitch on a doubled rope'.

We hashed out the nomenclature in a thread two or three years ago as to which was the b and which was the d. Still, I'd like to see the techniques renamed for the sake of clarification, like stationary doubled rope or 1:1 doubled.

Your DbRT is so much like SRT that very few people would understand.

That's exactly my point. They ARE almost identical. Other than the base anchoring of the SRT line, you are either ascending/descending one line or two.

What do you think, Tom?

 

[PUclimber]

TM,
Look at the sherrilltree catalog. Ddrt is the doubled roped technique which is your 1:1 system. There is no Dbrt unless you have something that no one knows about. The Drt is just the double rope technique using the 2:1 system. From what i know Tom is a wise man and knows his stuff and this point there is no arguing that the man is right.

 

[TheTreeSpyder]

Ummmmmmmmm with all due refverance to Tom; i believe other disciplines look at DRT as 2 seperate lines of support in a failsafe fashion; mostly of different elasticity ranges too. Somewhere's along the way; the tree sector etc. seems to have taken the same accronym for a single line doubled over a support to form a retrievable SRT.

So that in our DRT line isn't anchored at ground (inducing double loading of support and more line elasticity by length and tensile both); nor choked remotely to support/ TIP(that gives no double loading of support and higher elasticity than DRT by tensile). Our DRT is retrieveable and gives less elasticity; like our DdRT. Only our DRT would be 1:1 like SRT; DdRT giving 2:1 potential.

 

[Tree Machine]

TM,
Look at the sherrilltree catalog. [/QUOTE]The Master Catalog, Fall/Winter of Ascend? Ddrt is the doubled roped technique which is your 1:1 system. The Drt is just the double rope technique using the 2:1 system. From what i know Tom is a wise man and knows his stuff and this point there is no arguing that the man is right.[/QUOTE]No one's arguing. This isn't stuff I made up. The delineations are from a thread years ago in the Rocky J Squirrel era.

The Sherrill Master Catalog doesn't describe anywhere how to descend down a doubled line as asked in the opening question. The DdRT page 46 shows only ascenders, dual ascenders and marbar for going up a doubled line. The following page shows the figure 8's. The eared rescuescender will allow abseiling down a doubled rope, but the catalog shows the 8 set up for SRT. Coming down a doubled stationary line is not described in the Sherrill Catalog. It never has. Good catch, but does that mean it doesn't exist, or that I'm making it up?

There is no Dbrt unless you have something that no one knows about.

This is not my original stuff, so I can't accept credit for it.

Very few descend a doubled stationary line, I'm becoming more aware of that as time goes on. But I don't have something no one knows about. 1:1 descent down a doubled rope is what this thread asks about, so at least one other arborist has pondered the question. I just chose to travel down that road and have been climbing regularly in this unheard of style for better than 13 years. It would take a lot of convincing that no none else knows about it. It's been discussed through the years. Few climb it probably because it's not in the Sherrill Catalog. 1:1 descent has a number of advantages. If you can go up 1:1, why not come down 1:1. This is what the question asked, though he wanted to know if you could do it using a friction hitch. This is cool. We're staying on topic.

 

[rmihalek]

Yeah, I realize now that I used the incorrect terminology when posing the original question. I meant to ask about descending on a doubled rope (i.e descending on a rope that goes up and over an anchor point, coming back down with the two standing parts running parallel to each other all the way to the ground).

I'm still waiting on the chance to try descending on a doubled rope for a good distance. I tried the "low and slow" descent with a Klemheist hitch and it worked okay. What I want to do now is establish two TIPs, one with my usual DdRT set up and then a second, lower TIP on a doubled rope with a Klemheist hitch. The higher DdRT will be my backup in case I burn through the Klemheist or something else fails. Maybe I'll get a hank of that Bee-Line friction cord before I try this...

TM, you haven't mentioned yet how you descend on a doubled rope.:help:

 

[Tree Machine]

TM, you haven't mentioned yet how you descend on a doubled rope.:help:

How do I descend? Isn't it obvious??? You put on your bedroom slippers and sing the Periodic Chart of the Elements.



Duhhh

 

[PUclimber]

TM,
The big thing then is where did you get DBRT. We see the Drt and the Ddrt but everyone is trying to figure out where the B comes from.

 

[Tree Machine]

First, it's DbRT, small b. A thread three or four years ago. Tom was part of it, John Paul Sanborn. There were plenty others, too.

A quick use of the search function (which you apparently didn't do) of just the acronym DbRT shows 39 threads with a combined total # of views at 164,632. I was not even part of some of those threads.

I've done your research for you. Mebbe you should read through those and re-open some for debate.

 

[rmihalek]

The video is nice, but there's not enough detail of the set up. What kind of knot do you have your left hand on? What are you running the rope through on your saddle?

 

[Tree Machine]

No, it's not an 8.

Figure 8's, used in a traditional manner, will twist your rope, not acceptable if there are better alternatives. The Petzl Pirhana is a well-designed aluminum 8 with horns. I have one, but never use it. It'll twist rope also.

I much prefer to interface rope with steel, without any twisting.

 

[Tree Machine]

I use fairly simple stuff. I'll have to think back of what I was using that day. No pat pending. Not using anything that's not already out there, just might be using some of it in unique ways.


It varys quite a bit what I'll apply to a single or doubed stationary line. Either way, the device has to handle either the single rope, or the doubled rope identically. In the 11 mm world, a lot of stuff opens up to you. So very many pieces to try, so little time.

 

[Tree Machine]

I love the weightless feeling of a fast repel but I don't do it often. Mostly I go slow and enjoy the view.

Going off my porch in house slippers was not a fast rappell.



What were you using, or thinking of using to descend Mihalek?

 

[Tree Machine]

On a 2:1 system, twice as much rope goes through the hitch as in 1:1, plus you have additional friction over the limb or through a friction saver. You get heat and wear

Friction can be increased by increasing the force of pressure on the rope, or by distributing lesser force(s) over a greater surface area. A friction hitch is coering maximal surface area. A device is concentrating all friction on a specific, single place along the single or doubled line. A good piece will allow you 100% precision control over the friction with as minimal an effort as it takes.

 

[TheTreeSpyder]

Some thoughts:

Friction is a help on hold and descending/ hold or extension on jig; only fight it on ascending/ compressing rig.

Hanging still on DdRT is a 1:1 though; your weight pulls down on 2 lines that are pulling up on your weight; 1:1. 2:1 comes in like when you pull on 1 leg of line with effort; that causes 2 pulls on you as load. Just like pulling 1 leg of line that laces thru a pulley on load; the 1 pull of effort gives 2 pulls on Load. Or, if you grabbed both legs of line at oncet and climbed up; you would be pulling down on 2 legs of line that were holding you up for a 1:1.

Too much friction can melt a cord; i think there are more stories of this in rescue/ mountain SRT with someone trying to force descent on friction hitch. i stick with my model that friction hitches slide on descent in DdRT; because sliding the hitch is really lengthening that supporting leg of line; and just like 2 separate legs of support on a load; if one stretches or starts to fail, the other takes the load automatically. This automatic shift of load to the nonstretching leg of line terminating on saddle; unloads the friction hitch instantaneously; allowing slide. So at this point, there is lots less than half load on friction hitch; or i could descend on same gear in SRT as JP on DdRT. Figured that out and tested with scales after searching long and hard for friction hitch to descend on in SRT. SRT or DRT does not offer the system of support another leg of support to carry the load as hitch slides; so doesn't work; hitch clamps tighter(as system tries to effect support), overheats cord etc. So, i can't use same gear setup to descend in SRT as someone 2x as heavy/ but only half loaded hitch in DdRT; the mechanix are much different than than just the 'obvious' 2:1.

All friction counts; and adds up to load + descending rate etc. Friction at hitch and feet is nicer on ascending; because you have to fight the remote friction at support; but can relieve friction load on feet and hitch and move forward as needed. One catch on descending is, that less friction allows less support; that allows you to descend faster; that causes more friction(so increase in speed or weight also gives increase in friction)!

Friction spread out/ apart on descending like so much on support, so much on hitch and so much on feets etc.(to add up to support - your movement); give a break between friction points for cooling down, rather than concentrating all friction to build in just one point like just at friction hitch with pulley as support or several friction points instead of just one on lowering loads keeps line cooler etc. IMLHO.

i don't like coiling on Fig.8's and muenters; but think it seems Natural to hold brake hand/Bitters(line part after friction device) at 90 degrees/perpendicular to support/Standing Part (line part before friction device); and this gives more coiling i think. Holding brake hand/ Bitters inline/180 from support line/ Standing Part gives less coiling.

Friction is inevitable in DdRT for it is a simple machine; each force conversion thru a machine must have some inefficiency/ tax on force at exchange; or there would be a perpetual motion machine. These energies are neither created nor destroyed just recycled/ altered into another energy form; like the evil that wouldn't die in the Denzel Washington movie (appropriately named for my purposes) "Fallen"! The heat byproduct from the friction inefficiency is energy released to atmosphere; in partial exchange/ balance for all the sun/heat energy reigning down as part of this far reaching energy is neither created or destroyed principal!

A rose is a rose by any other name; just let me know what you call it! Many times i could not take credit as idiot nor genius; but as thief; when using 'new terms' / acronyms taken from other places and disciplines. Why re-invent the doughnut or wheel or whatever ya call it?! Peace!

 

[rmihalek]

TM, I was hoping that there was some type of friction hitch that could be used on a doubled rope that would work just like a Blake's on DdRT. I like the feature that when you let go of the Blake's, you stop. The thing that gets me about descending on a 8, is that you don't have that feature. You need to tie a hard lock to stop descending.

Was TreeCo correct when he said there is no knot in your left hand when you were descending off your porch in that video clip? If so, then you're just relying on this mysterious device on your saddle for which you can't/won't name for us?

 

[Tree Machine]

No, I just am trying to recall what I had up there.

As far as a friction hitch, I suppose something is possible, but we need to talk about heat.

Spidey started us on this, others have made mention, but let's look at heat real close, look at it in the practical perspective of the scope of our work, and keep heat generation in the realm of the tree, not recreational trees like redwoods and sequois, but all other trees that we climb and care for.

Heat and friction and ropes, and mass and gravity. Those are the ingredients for a good climb. Friction is required for us to overcome the effects of gravity which pull us down in an accelerating manner unless we apply an outside force, a pressure on the rope, an amount of pressure equal to, and opposite the force of gravity.

How the pressure is applied is, I think, is what's keeping this thread alive.


Using a traditional friction hitch, or a tress cord, or a split tail, you are depending on a maximal area of two opposing surfaces to create enough friction. Each wind picks up it's share of the work, and of the heat. The more wraps, the more distributed the heat dissipation. Heat concentrates in the friction hitch, not so much the rope. Heat and friction eat these friction hitches and they need to be replaced from time to time, and the performance changes as the hitch wears. Rope-on-rope friction.

With a device, you get the same friction, equal and opposite the force of gravity, sufficient to keep your (m)ass from hitting the grass.
Only this time, you're going from a widely distributed friction force of light pressure (hitch system) to a finely positioned, stronger pressure (metal pieces). The friction is the same. The heat generated is the same, just enough to oppose the force of gravity. The friction is accomplished by different means, that's all this discussion is about.

The 1:1 system may seem a challenge for many of you, but that is only because the limitations of the friction hitch do not allow it's practical use on a doubled, or a single 1:1 line.


Before I go any further I just want you to know that I love and enjoy the friction hitches. To adapt to mechanical methods does not mean giving up friction hitches. It's not an either / or. It's adopting different methods to be better all-around climbers. This talk of mechanical devices in tree care shouldn't insult your manhood. 1:1 systems do not have to replace the 2:1. It's just that in the climbing world about us, nobody climbs as much as the Arborist. We should be more skilled than any of the other climbing trades by the sheer number of hours we are actually climbing and using ropes. Besides, we know the friction hitch systems, which other climbing industries will probably never know. We need to keep friction hitches alive as part of our overall industry identity.

By stretchin our skill base just a bit, we can explore the ways of other climbing disciplines in ways they can't ours. They use devices, and generally 11 mm rope for which most pieces are designed. We've been in the 11 mm era for about three years now, but as an industry, we've only begun to explore mechanical devices.... well actually, as a group, I don't think that trend has even begun yet.

Mebbe it never will. Conventional ways, the tried, the true, the tested, they never go away. Friction hitches will always be unique to our discipline and should be preserved.

 

[TheTreeSpyder]

A difference in heat is also that the metal devices act as a heat sink; to drain heat away from production site on rope somewhat; especially aluminum. Whereas, a cord as a friction device tends to insulate/ hold the built up heat in one place/ while more is being produced in that same place.

The lower loading by half load on DdRT(compaired to SRT\DRT); then relieved as other leg of line terminating at saddle takes load; gives lots less friction thereby heat. But; if you can still be burnt or burn cord with that; just imagine the friction/ heat of cord fully loaded/ with no possible relief in 1:1 methods of no separate helper line to automatically carry loading(per previously dis-cussed model) when hitch tries to slide/ you force slide in SRT/DRT!

 

[Tree Machine]

Well-said, My Spidey. Looking more precicely at how friction is generated and where the friction is created allows us to know where the heat is being generated and then dissipated.

Spideys point about a metal piece acting as a heat sink, and cord-on-rope insulating and building up heat before it is lost is true. Heat has to follow certain laws of physics and for us to know just a touch about that can help us understand better what's happening right in front of us.

Heat flows spontaneously from an area of high heat, to an area of low heat, not the other way around. Things are not 'cooled', things lose heat. We see our weather as getting cooler overnight, but more accurately, the earth and air are losing heat as it flows spontaneously to cooler places in the atmosphere.

All that aside and getting back to a specific place on a rope, where there is pressure being applied to oppose the effects of gravity you are changing energy from one form to another; your downward motion, being stopped by pressure on a line from an outside force known as friction converts kinetic energy (the energy of the motion of mass) into heat. If you weigh 75 Kg (168#), you're on rope, you go from a hanging stop, drop down 1 meter and come to a complete stop, you have created a specific amount of heat, which will move from the area of high heat to the area of lesser heat spontaneously. If you weigh 100 Kg (224#) and do the identical same thing, it takes additional friction, additional opposing force because the mass of the object is bigger. This makes sense, without understanding the details.

Lighter guys make less friction overall, but light or heavy, something still has to be done with the heat.

If you create friction in different places, the heat is split up, create all the friction in one place, you get all the heat in one place. Increasing the surface area over which the rope passes will increase the placement and distribution of the heat over a bigger area; no 'hotspots'.

At this point we can talk about a couple classes of friction pieces called belay devices and rappel devices and how that applies practically to the treeguy as to which is which and why that's important to know.