Wooden Hand

ODSK presented a 2 day rigging demo at a temple in Kiso, Nagano. The Zelkova stood above a waterfall that ran into the amazing beautiful Kiso river. Here is day 1 of the demo.....

If I sound biased it's because I am !

VT is good on the HH. Sheesh, where is my Torse, super quick adjustability is right. Matty, anything other than vertical, except in a couple of cases, shouldn't need a chest tether. My beginner students always leave it clipped on, they accept not being able to move from the waist as part and parcel of SRT climbing. Funny.

Hello Matty, do you mean that for the most part of the climb you leave your chest harness/tether/keeper (whatever) clipped on?

The Hitch Hiker 2 works lovely for TRT !

It's a great idea, SRT shouldn't be seen as one anchor for everything, i.e. the base tie, level headed climbers should see a distinction between Access and Work Position anchoring.

You mean a high-line? It depends on the amount (kn) of pre-stretch, rope dynamics, anchor point strength and angle, rope defection at the anchor...etc etc etc.

Hi Steve. I didn't mean that I run lines parallel, I use 1 as an opposing anchor, a re-direct. I run it from one anchor because that way I can retrieve it like a normal ddrt anchor. Combined with a traverse hook, 3 lines, it is a truly amazing 3-dimensional anchor system. I put a thread on the srt section a few weeks ago, check it out.

Thanks Atree - Rich, yes, that and the wrench, these days I climb a lot with 2 srt lines from 1 anchor.

Hi all, The Maruichi team spent 10 or so days pruning and removing trees in North Ibaraki. The video shows a roped removal of a Castanopsis. Takashi's drone had it's first flight too, just 1 shot made the edit though. [ame] [/ame]

You can see, just about, that there is a large rigging ring set up to the right of the tree. A 2:1 was created (double whip tackle) to be hauled by the Smart Winch, into an adjacent tree. The splayed out branches were pre-rigged and cut to hang off the rigging ring so that the tree could be lowered into a much smaller drop zone than the initial size of the canopy.

I didn't get the question either but you made 2 great points. Firstly that of rip cutting/slicing timber to use the outer edge as a hinge, a hinge that can twist too, it is a brilliant technique if you understand internal tension and how to abate it. And seriously the most useful technique is that of pre-rigging. The subject is pretty huge and for the scenario you describe there are a bunch of ways to rig it up, leaving the mass on the limb, transferring it to the block or using sliding hardware like the rigging hub to form an inverted double whip tackle to lower the tip section out first. For your question: I don't see any use for doing that unless it is impossible to get the saw in because of bulges on the branch or stem. The point of pre-tensioning is to be able to remove larger sections more safely. Those that I see cutting like this are usually beginners who feel more comfortable cutting into a cylinder, it drives me a bit potty to be honest!

The logic of dropping your back-up to you knees is misguided. I think that this is another over-looked area in arb training though quite an interesting one to think and build systems about. There is the immediate thought of perhaps doing the work in another way if you anticipate intense stem shake. There is usually another way, found through logical thought and technique acquisition. Anyway, for me, the usual set-up is both above.

I agree, friction is the starting point. A rigging system cannot reduce further than the rope and tree, thus it is the best starting point. The basic models that are taught, pulley to reduce friction and friction device to apply it, are definitely not the only way to find solutions.

By the time we get on to dynamic rigging there are many layers of interaction. 1. Length of section - As has been stated, the centre of gravity determines the incoming force. 2. Rope type and length within the system - let us assume in your drawing that you are decelerating the cut section and stopping before ground impact. We have a broad spectrum of rope choice from fully steel like static to rock climbing dynamic. Most arborists in England use a polyester/polyester double braid though a more stretchy polyester/nylon is becoming known. In fact choice of sling type determines peak loading too. The cut section can depart the stem at different angles depending on the type of cut and wood type. Ordinarily it will project outwards keeping the rope at least moderately taught as it does so. Ground rigger interaction begins here. Do we choose to begin running the rope immediately or pausing? The outcome begins to be determined. 3. Position of half hitch - This is always the point in contention. The placement of it determines the final hanging position of the cut section, butt tie hangs vertically, balance point tie hangs horizontally and all angles in-between. Each angle will have a different peak load. I agree with Mike and Pete that lowering the half hitch toward the cut DOES NOT decrease peak loading. As long as it is tied beneath the centre of gravity the cut section falls EXACTLY THE SAME DISTANCE. The half hitch should never be allowed to slip of the bottom of the cut section. 4. Position of the block - The block should be tied as close to the cut as possible. This is where climbers misunderstand half hitch placement. It is the block placement that determines extra kinetic increase. As an aside, climbing line and lanyard should be tied, with one choking the stem, above the block and sling. 5. Dynamic movement at the anchor points - different cuts will influence the play of hinge released induced dynamic movement, so to will the decision of the ground rigger. And of course lets look at the tree in question. A 2M wide 15M tall beech tree will react differently to a 30cm wide 20 M tall red pine. 6. Energy transference - Where do you want to move energy to? I think relaying on the trunk to dissipate energy as the cut section impacts it is highly suspect, hazardous even, I do not recommend it.

Thanks!

Cinch style.

Thanks Ben, bottom and top tying sounds cool, I'm gonna try it. I guess you could add in redundancy in the case of anchor leg cutting too?

I'm coming from a place where 25M-35M trees are being removed, usually in a line, next to electrical and railway lines. My ideas are relevant to me and my job. I certainly don't go in and faff around and whatever redundancy is there is for safety. I have to trek in up to 2km and work on 70 degree slopes. Light weight is very important. If it's not working then it stays at home. I guess I see where you and James are coming from. As a subby climber you are supposed to go in a perform professionally, efficiently, productively and safely. As a company hiring in a subby they are expecting someone who can deal with any and all situations. So I ask you, how can you do this if you don't expand your technical vocabulary?

Oy vey ! Well ... whatever James, your prerogative is your own after all.

I'm busy, all tree related!

Cool man, where were you? There are areas of growth, Nagano has a lot of work, it's pretty much all removal work though.

What do you mean by tree? We are talking shape and scope of work, which is different all the time. Apart from the last (trt and srt), it really isn't too much to grapple with. I mean, you are climbing off an English Reeve system in your avatar! Surely you can set 2 srt ropes through a top anchor!?

Yes, for me too at first it replaced ddrt as a stand alone system, but back then I wasn't reflecting enough on the system as a whole. When I moved out to Japan and was suddenly faced with an entirely different scope of trees my technique had a sudden shock and I needed to find answers. With 99% rigged removal work here the trunk anchor stayed firmly in the access portion of the climb and I began to explore srt top anchors. On another note the DSRT stuff left me cold when I first heard about it, it seemed that the guys were using it for pruning mainly and since I wasn't into that kind of work I left it be. The first time I tried though I just couldn't believe the scope for safe and easy movement. It redefines re-directs, returns to re-directs and the opposing anchor thing coupled with a traverse hook is just insanely useful...for removal work too.

A follow up to my previous post. This one should boggle beginner and seasoned srt aficionado alike! SRT???? ??????SRT Anchor Part 2 As an aside I think that the srt system has a long way to go before it can really compete with ddrt as a stand alone system. In my opinion it is not positive to negate development of the srt concept by saying 'keep it simple'. Simple input doesn't mean simple output. I'm ready to discuss this if anybody is interested!