tree pulling knots

vega1

Hello all,
i need to pull a pine tree. has a slight lean. what is a good knot combination to use up high in the tree and on the draw bar of my tractor. something i can untie after it's had a good strain on it.

i've got good equipment and good help. we have pulled quite a few trees here on the gulf coast of texas after hurricanes. i have proper safety gear, saws, bull ropes, and a weighted bag to pull the line up in the tree.

this is all on my property and when down, the tree goes to the burn pile.

my worker that knows lines and knots has moved on to bigger and better. now i have to figure it out.

thanks guys, i appreciate your help

Quintrex

Take 2 turns around the trunk and secure with a running bowline.

If tied correctly, it will untie ok.

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Heightmaster

vega1

i'm no climber. i'll be on the ground the whole time.

thanks

Quintrex

One turn will probably do the job if you can get the rope up there ok.
I just like to go around twice to prevent rope slipping.

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Heightmaster

stirmantrees

running bowline has always been faithful to me.
I have on a few occasions done a series of wraps on big equipment and then tied off with a couple of squares. not pretty but does untie and is better that tying a knot that slips off or does not untie.
first, what you are tying to absolutely, positively, can not have any corners on it. it must be round, and the larger the better, 90 degree corners on a piece of metal that you tie to will cut the rope like butter under tension. second, make absolute sure that how it is being pulled does not slip it of the equipment.

for me, running bowline in the tree, bowline on the tractor.

kiwi_tree_steve

Running bowline, to high up in tree, with Throw bag ,or big shot! should sort ya!

i prity much ALWAYS tie off my bowlines, an easy way to do this it to double up the first bite, or the "rabbit hole" bit simply do two loops. i think its named a "Yosemite tie off" but can't rember

steve

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"You have to feel and touch a tree" Shigo

vega1

thanks, i've got a throw bag and a big shot. getting the line up high won't be a problem. a running bowline up high sounds good.

Eric Frei

Rope on rope not the best .....

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TrevMcRev

Using the shackle is a good practice. When placing heavy loads like when pulling with equipment/vehicles it's the cinching down rope on rope friction that snaps ropes, even high rated bull ropes.

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stirmantrees

i have to admit that almost every time i've busted a line it has seemed to not bust at the knot. Obviously it is because of other factors( nicked line, line rubs on something with an edge, the middle has gotten the most wear on it because it is what rubs on the tree the most , etc, etc) Now my uncle actually owns and operates a rope, wire rope manufacturing business in miami. Nice operation with some awesome equipment that actually spins, weaves, braids, etc. They make wire rope for cranes, ropes up to like 3-4 inches and well i'm sure everything you can imagine. He was the one who informed me that the knot is the weakest link and i think he did say something like 40%. So i am not arguing the probably much proven fact. I am just saying that failure has very rarely if at all at the knot.

now dont think i break ropes on a regular basis, but in my 16 years or so i have , well lets just say .........i've snapped a few

so , where has every body busted there lines? in the middle, or at the knot?

moray

When I have tested new ropes with my hydraulic test rig, the ropes have always broken at the knot. The knots shrink and change shape under serious load, and in doing so generate a lot of heat. In every case where I checked, the breakage at the knot involved clearly visible melting. There is nothing like watching a few knots break at much less than 1/2 rope strength to give you a real appreciation for the limitations of knots. On the other hand they are way too useful to give up--just always derate your rope by at least 50%.

Splices, on the other hand, don't change shape or shrink, so melting should not be an issue (I haven't checked). The rope always breaks right at the end of the splice at much higher loads than the knots can withstand.

stirmantrees

i wonder? does a bowline around an object(tree, pole, etc) help reduce the actual tension on the constricting part of the knot? meaning, does the friction the rope has 3/4 the way around the tree when it comes back to the knot reduce it enough to help. or does the knot at both ends distribute? or does the type of knot matter?
well i know the loop still pulls on the knot but could there be some distribution? im tellin you that i have rarely busted at the knot.
Now, logically, if i tie a knot in the middle of my line and put my international dump truck on one end and tie it to my broken bobcat on the other end and pull like a bat out of hell then naturally, i would expect it to snap at the knot.
but, does two end knots (bowline, and, running bowline) that pass around an object distribute some how? maybe so, we could be on to something.

I would like to see you moray perform some test with the above mentioned applications (end knots around trees for example. We might discover something interesting. really interesting indeed.
just brain storming.

ekka i do like the clevis application. i am pressing the purely rope knot thing.

moray

You are on to something, and this is a very good question, but the answer, unfortunately, is not a simple yes or no. Rock climbers like to use a top-roping anchor they call a tensionless hitch, which is just several wraps around a tree finally secured with a bowline. For this case the answer to your question is a definite yes because there is no way for any significant tension to reach the knot. A consequence of this is that the standing part of the rope, the part holding the person descending the rope, is perfectly straight where it reaches the tree. The security bowline does not deflect the line at all because it is not pulling on it.

If the rope only does a half wrap around the pole or tree, then the situation is much less clear. If, and this is a big if, the rope has no chance to slip or move or shake itself into some sort of equilibrium, then we would reap the frictional benefit you have suggested, and the knot would probably see about half the tension of the main rope. With a wrap and a half, this would probably drop to about 1/8th the tension in the main line. I have measured the friction of rope on wood for different ropes and various chunks of wood and the results pointed to a pretty good rule of thumb: each half wrap cuts the tension in half. To explain this by example, if you are lowering a 50kg load with a rope over a limb, the ground person holding the other leg only has to supply 25 kg to balance everything. Things work both ways: to lift the 50kg load, the groundie has to pull with 100kg.

I use the principle you suggested all the time when I want to test the true strength of a rope. I wrap it once around a big bollard, then once around a shackle, and then terminate it with a bowline or just an overhand knot. By the time the rope breaks there is unquestionably a lot of tension reaching the termination knot, but because the motion of the rope (there is some) was all away from the knot, essentially the knot is controlling the lowering of a very large load with two wraps around a steel friction surface to greatly reduce the controlling force. Two wraps has always been enough: the rope always breaks out in the middle or where it first contacts the bollard, never at the knot.

Finally, just to make this really tedious and long, you can tell by inspection of a particular setup of yours (rope wrapped around a tree, then secured with bowline to standing part) whether the friction around the tree has reduced the load on the knot. Look at the angles formed where the standing part passes through the bowline. If the standing part bends exactly 60 degrees, then the 3 rope parts form angles of 120 degrees and the rope tension is the same everywhere. Friction is doing nothing. If the standing part is straighter than that (deviates less than 60 degrees), then friction around the tree is indeed reducing the load on the bowline. If you can measure the angles, you can calculate exactly the relative tension in each leg.

stirmantrees

thus regaining the loss that the knot creates?
IF everything doesnt move or shake etc.
what about the circumference of object wrapped? ie big building vs 4 inch tree

moray

Yeah, I guess that's about right. The friction would protect the knot and maybe remove it from the equation as the weakest link.

As to circumference, the books will tell you it makes no difference. In my own limited experience this seems to be true. This result comes from the same theory of friction that says the friction between two objects has nothing to do with the amount of contact surface, only with the force pressing them together.

In the real world friction is not as simple as the theory has it (and the books acknowledge this point), so the equations are useful but not perfect.

stirmantrees

i suppose we could theorize that is why my ropes have almost always broken
other places. that it potential was not the weakest link.
of course im sure ive cut the ropes unwittingly, or damaged them somehow and not known it.
thanks for your time. very edifying.
vary interesting work you do. do you make rope?
my uncle owns miami cordage.

LONG LIVE THE BOWLINE

lonniels

I have always used the running bowline, with yosemite tie off, but using hardware might be the better way when pulling with equipment.

Eric Frei

One important factor other than friction is bend ratio. The larger the dia the better for rope.

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moray

Exactly right. Those book writers have no real-world experience, which is why they talk about infinitely supple ropes, perfectly smooth surfaces, and all the rest.

BTW, that shackle you pictured looks identical to some I use for pulling experiments. After a test of 2 or 3 tons, I often have to loosen the shackle pin with pliers even though they are barely hand tight when I start. I got 'em because they were cheap, not because they were well made.

Eric Frei

Yeah, what is the go with that?

I have two small ones on my trailer chains, if you finger tighten them solid you'll need pliers or a nail in the eye to undo them. They must have something in the design that makes it tighten up under load.

And guys, remember the SWL of these shackles is 20% of it's breaking strain so it's a real cheap but sound way to be mean to some gear without going broke doing it. (Just that I see people using biners often)

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Trusa

A good technique using the Bow Shackle Ekka, something I will try tomorrow pulling a big backward leaning ivy covered pine with the Landcruiser.

The movement of rope/chain under tension whether from pulling or the weight of itself on the pin of a shackle will create a tightening effect. The full theory of why it tightens and doesn't loosen I can't explain, but for recovering 4wd's or towing it is advisable to tighten your shackle finger tight then back it off half a turn or so. Of course, on long trips/long term applications are considered regular checking of shackle pins is advisable.

I guess the same theory applies to this rigging technique.

Previously I had always used a running bowline on the tree and a bowline to the vehicle. No tight binds and no breakages yet........