Using single line technique for more than ascent

X

xman

Location
Costa Rica
Hey guys,


My initial post about the Rig vs. unicender was not specific enough. I am asking if anyone is actually working a trees crown on an SRT system, not just ascending. We currently only climb on an srt system anchored at the base of the tree. For limb walks, a hand ascender/ pulley combination ran through the RIG works pro. I am looking for input on the unicender setup in the same fashion. With the SRT tech. you can redirect at will, through natural crotches, or use slings with a revolver knowing that you will return to the zone of the sling.

Thanks in advance,

X-man O.G.
 
I ONLY use the Uni for climbing, nothing else. for the last six years I;ve been a UniFlyer!

the only exception is when I've taken a friend climbing. Then, I've set us both up with RADS so that there is NO confusion. Now that I have two Uni's I don't use RADS.
 
I've been climbing srt exclusivey for about a year.I use the unicender with a revolver carabiner below it for limbwalks. For ascent I add a pantin and an ascender with a footstrap. Apart from my lanyard I carry a couple of slings with carabiners as you mentioned but you don't need revolvers as clibing srt the rope wont move in there.
what I love about this system is that it's very efficient and not very gear intensive while offering more climbing options than ever
 
been exclusively SRT since october 2008. use the fate revplver set up. although now the kong robot is my tool of choice. still want to try a uni. i'm a big fan of using hitches. i like how hitches can be tied in so many ways to speed you up or slow you down. I like how you have so much control when swinging and limbwalking with a hitch.
 
single line technique for more than ascent

High precision control is the key,

SRT since the late 90's. The question asking if we use SRT for more than just ascent, I was expecting some novel, new unique SRT use, but working the crown, too?.

I don't use SRT exclusively, just when it suits the moment, the particular climb or the mood. Any new device gets an SRT run-thru, as well as DdRT and DbRT just to fully explore the abilities of the device.

So, a lot of SRT mixed in and amongst the other two rope techniques, which ever is the most advantageous given the particular tree and what is to be done in it. And depends what piece is being used.
 
I've been using SRT more and more lately for ascent and work (Rads). I really like the simplicity. I guess there are two reasons I'm not completely sold on it yet.

1)The fact that your life line is running the lentgh of the tree exposed. One inadvertant swipe of the handsaw and your down in a hurry. Not to mention the anchor on the bottom exposed to groundies, falling wood, passerbys.
2)The added load on the TIP. Trying to get your final TIP as high as possbible (especially from the ground) and doubling the load on it can sometimes be.....well, scary.

I do really like the idea of easy re-directs and.... just the coolness factor.
 
The issue with 'double loading' isn't really accurate.

With a ground anchor there is much more rope in the system to absorb the load by stretching.

7'16" KMIII in SRT mode has MUCH more stretch than any typical climbing rope in DdRT. When you double rope the 'strength' doubles and the stretch halves.

Some of the load is absorbed by the friction of the rope over the TIP.

Arbos have rigged lots of wood down using a ground anchor...does anyone know of a rigging rope being cut or compromised during rigging? Training everyone to watch out for the climber's ground anchor isn't any different than training them how to rig. Use high viz ropes so that they stand out.

Climbers learn how to choose a TIP by experience and guidance from more experienced climbers. This is the place where the art rather than the science comes in. There is NO way to easily test a TIP. That said, if a DdRT TIP is chosen it should, theoretically, have a safety factor of 10:1 to cover the unknowns. Truth be told I bet that many TIPs used would likely only have maybe a 3:1 or 4:1 safety factor. In the case of a broken TIP I wonder how many climbers might get hurt. So...if a DdRT TIP is chosen properly and then the same TIP were used for SRT the safety factor should still be 5:1...is that enough?

A way to decrease the load on an SRT TIP is to spiral the rope along the lead to add more friction or run the access line through several branch unions to change load angles and loads.

Climbing SRT does require more attention because there is SO much new to keep track of. SRT is way easier to learn than how to use a 'smart phone' :)
 
If I may add a few comments.

First, the focus is ground tied SRT. A ground tie does put twice the load of the climber on the TIP, but it minimizes shock in case of a fall far better than any other tie-in method. But before you read too much into that bear in mind that the TIP is already 'double loaded'.

Of course the other advantage of the ground tie is the fact that the 'loop' can contain many branches and if the TIP should blow, the limbs below it in the loop may arrest the fall. The problem is, the climber is gonna fall twice as far as the distance from the orginal TIP to the lower limb. The danger here is contacting a limb during that fall.

So we have two aspects to consider - static and shock loading. Just to be clear, static is when the climber is stationary or climbing. There's a bit of dynamic stroke loading when climbing, but it's not much. Shock loading would only need to be considered if the climber falls.

In a static mode, if a rope runs cleanly from the TIP to the climber, the maximum STATIC loading on the TIP is double the climber's weight. One has to be very careful about how he evaluates additional friction on the rope over limbs between the TIP and the climber. That friction can vary and change through the process of climbing.

As far as the rope being exposed for the full length of the tree, that is true, but as Tom said, has anyone ever cut their rope because of that? Also the same inadvertant cut on a DdRT would send the climber to the ground as well. But, we're suppose to be tied in twice BEFORE we start cutting.

Then a word about shock loading on DdRT. While DdRT does not double the load on a TIP in a static condition, a fall on a solid DdRT setting could easily produce very heavy loads on the TIP, again like Tom said, the stretch of the rope on a DdRT is halved, the shock can be quite high. Plus, we generally strive for an isolated limb. If we are on an isolated limb and it blows, then a lower limb will not catch the fall as it could with an SRT ground tie.
 
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I am asking if anyone is actually working a trees crown on an SRT system, not just ascending.

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Working an entire tree off SRT with the Uni is quite enjoyable.

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For limb walks, a hand ascender/ pulley combination ran through the RIG works pro. I am looking for input on the unicender setup in the same fashion.

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With the Uni clipped into a HUT it will self-tend slack when there is some weight on the tail. The Rig has no upper attachment point so will fall on a slack rope and require pulling the tail to tend slack? This will make the Uni more desirable on some types of limb walking maneuvers. An ascender/pulley combination works with the Uni and I find it necessary in returning from extremely awkward positions.

Dave
 
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I am asking if anyone is actually working a trees crown on an SRT system, not just ascending.

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Working an entire tree off SRT with the Uni is quite enjoyable.

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For limb walks, a hand ascender/ pulley combination ran through the RIG works pro. I am looking for input on the unicender setup in the same fashion.

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With the Uni clipped into a HUT it will self-tend slack when there is some weight on the tail. The Rig has no upper attachment point so will fall on a slack rope and require pulling the tail to tend slack? This will make the Uni more desirable on some types of limb walking maneuvers. An ascender/pulley combination works with the Uni and I find it necessary in returning from extremely awkward positions.

Dave

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Ahhh-haaa! The Rig, et al, will do limb walks very nicely. You simply leave the upper ascender at the tree and walk out by releasing rope through the Rig. The smoothness and control is spectacular since you have a 3:1 on the down rope. When you start to come back to the tree, you can pull the down rope towards you instead of away from you as you'd have to do without the ascender at the tree.
 
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Ahhh-haaa! The Rig, et al, will do limb walks very nicely. You simply leave the upper ascender at the tree and walk out by releasing rope through the Rig. The smoothness and control is spectacular since you have a 3:1 on the down rope. When you start to come back to the tree, you can pull the down rope towards you instead of away from you as you'd have to do without the ascender at the tree.

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I have used that technique but do not like it. It puts more rope in the operation than is necessary. Also if you lose hold of the tail it can fall out of reach.

I prefer to add mechanical advantage only when necessary such as high pressure negative leans when out on the very tips. For this I use my ascender/pulley combo just to regain balance and return maintaining balance by hand over handing the top rope while the Uni self-tends slack.

Dave
 
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...I have used that technique but do not like it. It puts more rope in the operation than is necessary. Also if you lose hold of the tail it can fall out of reach.

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The more rope could be an asset or a liability. But with the RADS, that's an option that's available without adding a thing, reconfiguring or anything else. Another option is just take the upper ascender with you, that's not bad either.

And then you do have a simple reconfigure and that is to remove the upper ascender, do the limb walk whatever, reattach the ascender as needed or desired.

I clip the tail through a biner to keep it near by and you don't even have to wrry about holding the tail. Even if you did lose it, you can still pull the rope through the Grigri/Rig, you'd just be pulling it away from you sorta like in a DdRT.

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I prefer to add mechanical advantage only when necessary such as high pressure negative leans when out on the very tips. For this I use my ascender/pulley combo just to regain balance and return maintaining balance by hand over handing the top rope while the Uni self-tends slack.

Dave

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Yep, I understand that. In fact, a RADS is already setup for that. You simply go from climbing to limb walking, to regaining balance, to walking back to the tree - nothing changes, nothing gets added almost like one, single universal climbing machine.

I had a similar discussion about RADS vs DdRT with some dyed-in-the-wool DdRT guys. They talked about simplicity, non-gear intensive, what they could do on DdRT, etc. When the details started to trickle out, these same guys that talked simplicity and not gear intensive, were using Pantins, split tails, pulley tenders, rope sleeves, etc. I made up a gear list for a RADS and asked them to make one up of the gear they'd use to do all the things they said. Their list was as long as my RADS list and they could do no more and couldn't climb as efficiently either, and in heights above say 60 feet, had no immediate direct emergency escape like I had with RADS.

The really strange thing about the guys I was talking to actually used a RADS to get into the tree, then they switched over to DdRT, so they actually carried two systems on them.

One of them got caught in a sudden storm, descended DdRT only to find he'd nearly ran out of rope. He pondered what would have happened if he'd been up another 10 feet and wound up going to a RADS.

The RADS-Unicender will likely be a closer thing because they are both SRT. But, I'm hearing some of the same things, the Unicender plus this little Pantin, plus anything can be used for a chest harness/strap, you can add a pulley and do..., etc. Notice in my RADS description, I never say if you add a simple, single anything. I never have to throw or lower something to the ground, etc. It's one system and always the same system.

I'm really not trying to 'sell' RADS or as they say, 'extole its virtues' or diminish in any way the Unicender. But, I think it is appropriate to present an honest, open comparison of the RADS to other techniques.
 
Well NOW which is it?
How can the load be less than doubled because of friction at the TIP, but the stretch on a DdRT be half?..

I'd like to see some science there and I would think it is obvious that SRT does not provide double the stretch in shock loading situations. The friction at the TIP reduces stretch on the standing side, to something far less than half, depending on the amount of friction at the TIP.

Tom,
I don't care for your logic, that half the SWL factor ( from 10:1-5:1) is acceptable.. how can you even talk in those terms anyhow.. what kind of number can you put on a branch union?

John Ball said something to the effect that arborists do not die from TIP failures... Has anyone here ever even heard of a failure in TIP?

If you are pruning, what kind of forces can get generated by a handsaw cut... if you are using a chainsaw, you should have a second TIP anyhow..

and lastly.. I haven't heard anyone mention side loading in this discussion... I would guess that is the only way a TIP point could fail, should the climber be following other safety protocols.. SRT will change the vector forces in the climbers favor, causing less side loading..

That said, I do like a very high TIP and wonder just how high I can push it safely...
 
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The RADS-Unicender will likely be a closer thing because they are both SRT. But, I'm hearing some of the same things, the Unicender plus this little Pantin, plus anything can be used for a chest harness/strap, you can add a pulley and do..., etc. Notice in my RADS description, I never say if you add a simple, single anything. I never have to throw or lower something to the ground, etc. It's one system and always the same system.

I'm really not trying to 'sell' RADS or as they say, 'extole its virtues' or diminish in any way the Unicender. But, I think it is appropriate to present an honest, open comparison of the RADS to other techniques.

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Keeping in mind I plan on getting a Rig to use in a RADS system because I can recognise its attributes for my intended use, I do not think an argument based on which one uses the least support gear is viable.

I am not as strong as I once was. I like the little helpers. But a young and strong climber needs nothing more than the Uni on a tether to enter and work a tree. So that would win the "least support gear contest" but does not address if it is the best tool for the job at hand or the person doing the work.

Dave
 
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Well NOW which is it?
How can the load be less than doubled because of friction at the TIP, but the stretch on a DdRT be half?..

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What would happen at the TIP if you wrapped a rope around the limb twice and tied it off at the ground? There would be little, if any, force on the anchor side so the only force on the TIP would be the weight of the climber.

Of course that's an extreme example, but it's easy to see how friction could reduce loading at the TIP. But even in the normal looped limb, there is some friction and there could be more than we think. In any event, any friction over the TIP can reduce the loading on the TIP.

That 2x thing is theoretical where friction is considered insignificant, but due to light dynamic forces of climbing in additon to the climber's weight, I believe forces of very close to 2x can be likely.

Now turning to the DdRT. The DdRT is a doubled rope where each strand supports one-half the climber's weight. The forces in the rope combine at the TIP to load it with the full weight of the climber.

As for catching a fall, a single rope would have a certain stretch factor. Two pieces of that rope tied to the TIP and climber, such as in a DdRT, would only have half the climber's weight each, so they'd stretch half as much.

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...I'd like to see some science there and I would think it is obvious that SRT does not provide double the stretch in shock loading situations. The friction at the TIP reduces stretch on the standing side, to something far less than half, depending on the amount of friction at the TIP.

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SRT will likely provide far more than double the stretch of a DdRT setting. Let's start with no friction, that's easier then I think, friction will make more sense.

Let's say we are 10 feet below our TIP on a ground anchor, and our TIP is 50 feet above the ground. How much rope is between us and our anchor? 60 feet - 50' up to the limb and 10' back down to us. That's 60 feet of one strand of rope. If we fall, we fall on a total of 60 feet of rope. That's a lot of stretch and hence shock absorpton.

Now the DdRT setting. Again we are 10' below the TIP but because our rope is doubled back to us rather than to the ground, each strand of rope supports half our weight. If we fall, we fall on two strands of rope equally sharing our load so it only stretches half as much as a single line. The equivalent would be a single strand of rope 10' long, with half the stretch of a normal SRT rope. If we fall, i'd be like falling on 10 feet of rope with half the normal stretch.

Now let's add friction to the SRT ground tie. How much friction do you want? We really don't know what it is but there are two things to consider. The friction will be dynamic because the rope is moving and there may not be as much friction as we think. For example, if we were holding the end of the rope instead of tying it off at the ground, could we support a 200 lb climber? If there were enough friction we could, but in reality is there ever that much friction? Probably not. So in order to calculate how much actually loading there would be at the TIP, we'd need to know how much friction there was. But I'd say, in most cases, it would be significant, but a single loop over a limb could never have enough friction to reduce the anchor side force to zero.
 
Daniel,

The safety factors are from rigging or just grabbed out of the air to have something to talk about. They could be X or Y for that matter.

All of the discussion about loads on the TIP have been thoroughly thrashed when it comes to rigging. Using natural crotches or hanging a friction device in the tree v. having the friction controlled on the ground changes loads up top.

I've done all of this at workshops using nothing more than cord, hardware store pulleys, a piece of firewood and a 150# game scale. The multipliers are amazing to see. You don't need to use expensive dynamomters to demonstrate concepts.

I don't have the inclination to take the time to rewrite a whole article on loads and ropes. The nature of a forum is to assume that people have a general understanding...or they will do their own back-research.

speaking in safe generalities is good enough for me. Carrying on the discussion is important and interesting.

You're right...TIPS rarely break. But they do and the strength needs to be considered. Too often the difference in loading of an SRT v. DdRT TIP is the first thing that people trot out to completely dismiss SRT. This difference is easily accounted for but it does take a better understanding of forces.

SRT demands a much more indepth understanding of climbing and rigging because it is still in it's infancy in tree care. A few of us pioneers have been climbing trees on SRT for years. We're thrashed a lot of these details out. It takes too much to start all over from the beginning everytime.

I wrote the SRT article in the Archives in '02. by then, I'd been climbing SRT for quite a while.

I wish that I was a better writer. It seems like maybe my passion for SRT is coming off as confrontational. That is not my intention. Sorry....
 
Ron, I in a way see your point about the days are numbered on manual climbing. The way I like to look at it is, that it all comes down to education.

If a new climber is taught how to climb from scratch ( one harrnes and one rope for ascending and descending) then once that climber mastered that he/she is taught a new hitch and knot. In this manner of learning there is a span of control. I always cringe inside when I see a new climber starting with a new device and not a simple hitch, knot and harrnes. Plus it will give the new climber an appreciation of climbing and a feel for how systems will act in diffrent situations.
 
Tom, no need to say sorry for anything you say. I would like to think that as long as you stir the pot ( respectfully ), you will be ingaging people to think a little more on what they do.
 
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