Knot question

[v8titan]

I'm looking for the best knot to tie a hook to the end of 1/2" bull rope. I want something that will untie easily. Let me qualify that I'm not a pro and just use the rope for pull downs of medium size oak trees on a wood lot.

Tom

http://i38.photobucket.com/albums/e124/v2tom/DSCN0019.jpg

 

[Tom Dunlap]

If you're using only half inch rope it should be double braid or some other high strength rope.

Why do you need to tie a 'hook' to the rope? Do you mean a snap or carabiner?

A splice would be a better solution. using a knot will reduce the effeciency of the rope a LOT.

A better solution is to use a running bowline that will choke tight to the stem. use a throwline to set the pullover line high in the canopy.

 

[Kneejerk Bombas]

Tom, you missed his picture. It looks like he has a hank of 1/2'' true blue and a nonlocking steel rope snap.

 

[beowulf343]

To tie that rope to that snap i'd probably use a bowline with a yosemite tie off.

Like tom though, i'd use a running bowline to pull over trees.

 

[v8titan]

Thanks for the feedback so far. I use the non locking snap because it is easy to just clip in when looping around the tree. Sometimes I toss the line 15 feet up around a crotch in which case the mass of the hook helps in the throw. I will experiment with a running bowline as an option. I'm new to some of these knots and just looking for safe methods.

Tom

 

[Kneejerk Bombas]

You don't want to use that snap for that application. The snap slides up the tree and you don't know how it ends up. The rope could be against the gate and just when you need the pull, the gate could bend off to the side and let the rope go.
Another problem is there is strength loss in the rope where it meets the metal, and if you tie it off with a bowline, you'll lose more strength, up to 50%!
Have you ever used a throwball and line. That way you can get the rope up to where it should be, even if you want to go 50 feet or more. It's fast, easy, fun, and the leverage you gain makes the pull so much easier.

 

[v8titan]

You don't want to use that snap for that application. The snap slides up the tree and you don't know how it ends up. The rope could be against the gate and just when you need the pull, the gate could bend off to the side and let the rope go.
Another problem is there is strength loss in the rope where it meets the metal, and if you tie it off with a bowline, you'll lose more strength, up to 50%!
Have you ever used a throwball and line. That way you can get the rope up to where it should be, even if you want to go 50 feet or more. It's fast, easy, fun, and the leverage you gain makes the pull so much easier.

Thanks Mike.

I give the running bowline a try. No, I have not used a throwball and line in the past. I'll look to pick one up and give it a try, sounds like a better way to go.

Tom

 

[John Paul Sanborn]

Anpther option is to run the line through a sturdy crotch and then tie it off above the knotch.

For this I use a cowhitch for lite pulls and running boline with a marl above it for heavy pulls.

Just ensure the line is well isolated to as fiar as possible thought the tree and any slack is tensioned out prior to cutting.

Seems obviouse, but I've seen people F/U those on a number of occasions.

PS, when pulling big wide trees, I've set the line running through several stem crotches to get an even pull then tie off down line with a static bo'lin. In this application a running bo'lin will compress the crown and reduce efficientcy of of the pull.

 

[Manco]

If you're using only half inch rope it should be double braid or some other high strength rope.

Why do you need to tie a 'hook' to the rope? Do you mean a snap or carabiner?

A splice would be a better solution. using a knot will reduce the effeciency of the rope a LOT.

A better solution is to use a running bowline that will choke tight to the stem. use a throwline to set the pullover line high in the canopy.

I like using high -STRETCH ropes for pulling trees better than the low-stretch ones. A low-stretch rope I like better for lowering pieces.

 

[woodchux]

I use 1/2" Arbormaster 8100# rope to pull over trees all the time.

When I use the rope-along I use 1/2" 3 strand.

If its got a back-lean than I'll get out the 5/8" or 3/4".

 

[woodchux]

When I tie a rope snap on the end of the line, I'll use a double or triple fisherman.( not the easiest to untie, but can usually be loosened )
IMO A running bowline would be a better choice than that snap though. The force of the tree landing on the snap when hitting the ground can render the snap unsafe very quickly.

 

[John Paul Sanborn]

When I tie a rope snap on the end of the line, I'll use a double or triple fisherman.

An anchor hitch or a jack bo'lin will come apart much better then a fishermans knot, since this is a running knot ment to tighten up under load. Which is why it is used for a noose with 13 wraps.

I do like a fishemans, or scaffold knot when using a carabiner, because when you take the carabiner out the knot just falls apart.

 

[TheTreeSpyder]

Lots of good points of knot theory; and also about how the snap could hang up on line while sliding up Standing Part to seat on tree.

There is also a consideration about how the straight metal snap; could become leveraged around the arc of the tree. Truly, a running bowline would be better to seat like that. Because the rope could flex around the arc in tree shape; instead of resist bending (thus leveraging device) by a snap.

On the flip side; the knot to proposed snap would not be in the higher tensioned Standing Part; but rather in the buffered zone of the Bitters; after friction on host tree. In a standard usage; the snap/ running bowline would have leverage over the pull of the Standing Part too(so less tension on Bitters from this end too). The line tension on Bitters could be increased up to 2x though; by sharp bend/ bent backwards around with the angle of the Standing Part making 180 after snap/bowline/ running eye. This would really test knot connection and eye; even with running bowline. But could really leverage the stiff/ non-flexable/ metal straight snap device around the roundish shape of tree. Flat metal connection devices should only float freely in air, or only mount/ run along side on straight/ straight runs; never allowed to potentially leverage their stiffness on any kind of angle.

i'd use a running DBY. But also like giong through fork and lacing down back of tree to tie off above stum cut; with knot on back side for easiest release/ un-burried and close to sawyer/ closest person to tree, to utie quickly and hopefully evacuate line.

Also as side note, i think snaps are more self aligning(about foolproof?) than krabs (krabs can be leveraged even by straight line pulls by miss-positioning as Tom has brought to light). So snaps are more suitable for remote locations in system sometimes.

IMLHO; from the cheap seats opcorn:

 

[Ekka]

V8Titan

Lots of ideas but no-one asked the right question and you didn't tells us either.

How are you pulling these trees down, by hand, machinery, truck etc?

Coz if you are using a vehicle assisted pullover with a running bowline you have just decreased your rope strength to 50% of what it's rated at.

If using excessive force such as a vehicle or truck put a shackle into the system so you don't get rope rubbing on rope.

Here's a short video link on what I mean, 23secs and 2.2mb wmv

www.palmtreeservices.com.au/video/shackle.wmv

and a pic of it up the tree

 

[v8titan]

V8Titan

Lots of ideas but no-one asked the right question and you didn't tells us either.

How are you pulling these trees down, by hand, machinery, truck etc?

Coz if you are using a vehicle assisted pullover with a running bowline you have just decreased your rope strength to 50% of what it's rated at.

If using excessive force such as a vehicle or truck put a shackle into the system so you don't get rope rubbing on rope.

Here's a short video link on what I mean, 23secs and 2.2mb wmv

www.palmtreeservices.com.au/video/shackle.wmv

and a pic of it up the tree

Ekka, Good question.

I'm generally doing the pull downs by hand. I tie in to the target tree with snap (now trying the running bowline). The other end I tie off to the base of a large anchor tree along the intended fall line. I make my hinge and back cuts and leave enough meat to hold the tree in prep for the hand pull down. Occasionally, when the tree has a severe lean in the opposite direction of the intended fall, I use my tractor. Were not talking about serious rope tension though and I don't think I am anywhere near the breaking strength of the 1/2" Samson stable braid rope I'm using (I think it is near 9000 Lb). Trees are typically 12" to 18" diameter.

Tom

 

[John Paul Sanborn]

V8Titan

Lots of ideas but no-one asked the right question and you didn't tells us either.

How are you pulling these trees down, by hand, machinery, truck etc?

that was what i was infering with light or heavy pulling, machine or MA device in my book is heavy, whilst one or two men would be light.

 

[TheTreeSpyder]

Loss of tensile from bend in knot system is another point for going thru crotch and tying off at the base of the tree; especially with stiff rope(gives softer initial bend as Bitters doesn't bend Standing Part). The rope stiffness also means easily over impacted system and no elastic storage to store force to preset pull distance nor to store force to pull along /assist tractor.

i think the actual tension on the bowline would be determined by the pulling force and bend in Standing Part/ how flat the teepee was. Bowline is not a support leg here. i like bowlines with longer eyes in these situations, so that the dual legs of the eye take the raw forces, and the force to the weakness of the actual sheet bend to self to form eye/ bowline(where dual straight support of eye ends); is buffered by some bark friction. A DBY giving even more strength and easier to untie. A throwline kit (and some practice donated to race aroudnd the L-earning curve) here would be getting a lot of power and safety very cheaply; even a weighted string would be great here until then
IMLHO. Also in addition to more leverage by higher points achieved, can more likely use elasticity of tree to store force in to help with pull as well as store force to preset etc.

For hand pulling i'd go with a Z-rig; and a self tended prusik for holding pulled tension in system at 2/1 point and then 2 hand the Z-rig for 4x pull potential. Could tension, and let it hold tension, then cut, then pull finishing tension. Even looped around ground tree and put only pulley on Standing Part would give 1hand 2x force for actual pull or preset. This also would avail to hanging on it perpendicularly to leverage (or even impacting it wit'my huge body mass) once the line system is tightened linearly (pro-viding system is holding tension on own). Even just tighten line hard that you are to anchor tree, and jumping perpendicular across it suddenly can give high leverage X impact for possibly less effort/ more hinge on final pull.

i'd also all ways back-up (especially 1) man hand pulls and potentially high power tractor pulls with a wedge if in the batter's box when they are applied; especially on a back leaner. Both to aid the pulls to force more hinge control/ strength and as a fail safe.

Also: Direction of pull should be into gunned apex of face ( to get most control power out of hinge per force you apply) and let hinge force steer in good wood. With enough pull in good wood, sideways push/pull to steer only replaces what the hinge would do automatically/ for free. Think of hinge(especially tapered) in good wood as a multiplier that you can run input force of wedge push or line pull thru to adjust sidelean; or fight sidelean without this final multiplier by steering more with wedge/line direction at an angle across gun. The range of sidelean that can be handled by wood and hinge pulled straight is a question of experience. But, direction of force is a very important quantity here, and shouldn't be just automatically changed because of some sidelean. The power tweaks/understandings giving more power to target for effort and thereby safety; especially if pulling alone(?).


Oooops, looks like it is that time again :taped:

 

[v8titan]

TS,

I do most of my pull overs alone and you bring up a good point of using a few wedges on the back leaners. I try to use them primarily to keep the saw from binding if I make the hinge a little too narrow (I try to avoid this for safety sake). On the side leaners, I don't take any chances. I always keep the hinge thick and use maximum pull force for the take down.

Tom

 

[knudeNoggin]

there is strength loss in the rope where it meets the metal, and if you tie it off with a bowline, you'll lose more strength, up to 50%!
--------
Coz if you are using a vehicle assisted pullover with a running bowline you have just decreased your rope strength to 50% of what it's rated at.

Where are you guys getting this "50%" figure?
Bowlines alone test higher than that (YMMV on rope type), and in the choker
use they'll not be getting full force of the pull.

As for using hi-STRETCH rope, well, until it snaps--then you might not like it!

As for tying to that snaplink, it appears that the rope barely fits through the eye,
so an Anchor Bend/Hitch aka Fisherman's Bend couldn't be formed; one could however
tie this hitch to the standing part (instead of tying a Scaffold knot), and then it
would be easier to untie (than the Scaffold). I'd think that given the close fit of
rope through hook that it wouldn't even slide well but frequently snag ... .

For a simple hitch to the hook eye, try a Collared Half Hitch: reeve the line
through the eye; make a Half-hitch around the standing part/mainline;
take the end again around the standing part (in the direction one would go to make
a Cow hitch--opp. to HHitch direction, i.e.), and bring it back to tuck out THROUGH
the Half-hitche's loop (so now the HH will nip both mainline & end which pass
through it in opp. directions).

*knudeNoggin*

 

[Ekka]

<meta name="keywords" content="rope strength, knots, pull rope, bull rope, breakage, bowline, running bowline" />

<meta name="description" content="details and links to knot strengths and rope failure tests" />

Where are you guys getting this "50%" figure?
*knudeNoggin*

http://www.deepcreekyachtclub.com/WebPage/KnotStrength.html but it doesn't have a running bowline.

http://www.ropeinc.com/ropetensilestrength.html general comment in 2nd paragraph.

This is very interesting, especially as many of us dont use brand new ropes every day.

http://www.xmission.com/~tmoyer/testing/pull_tests_11_98.html

Now I'm sure you can find more by searching. But a good general rule of thumb is 50%, I have only had rope failure when snatching logs and I use pretty beat up rope for that.

I know of one guy who repeatedly used a running bowline on vehicle pulls without a shackle and it broke where the two met, it's a high friction point.

Aged rope can be a lot lower in strength already, then add a knot and before you know it you can easily be around the 50% mark.

It was interesting in that link to see the Humvee was dragged across concrete with 5000lbs of force. The general engineering perspective is wt of object + friction at tyres (must have been smooth concrete).

I have commonly heard that vehicles will generally pull around 1.5x their own weight, so for example a lead foot pulling a tree over with a 4000lb 4wd can easily put 6000lb of force onto the rope.

Now the numbers come into play. 6000lb of force shouldn't exceed what percentile of rope strength as a safety margin ... what 20%, 50% etc.

Lets be bad ass and say 50%, so we get say 6000Lb pull we need a 12000lb rope. But if that rope is aged (lose 25% conservatively) and has a knot (another 35% optimistically) it equates close to 6000lb which is now close to border lining your vehicle pull.

I must say I have attended a fair share of home-owner pull overs gone bad and see plenty of busted 3 strand.

So in the scenario above being optimistic you can see the picture. In reality that rope should be around 18,000lb for that 4wd pull.

I have a 7/8" double braid pull rope for big gum trees. It is rated 20,460lb breaking when new, that's what I use on my 4wd to pull large trees over, with a static bowline tied to the pin of a steel shackle run up to the tree (no rope on rope friction).

Run those numbers on my rope you get 20,460lb goes down to 15,345lb for aged rope ... down to 9,974lb for knots ... my vehicle is putting 5000lb of force on as it's a light 4wd and I'm around the 50% mark.

This is probably why I have never ever had a bad scenario.

For a kanga pull I use approx a 9000lb rope.

I'm sure I read somewhere but cant find it that an old retired climbing line with no visual flaws was tested to destruction with a figure 8 knot in the system (coz that's how we climb). Low and behold on 2 tests it busted around 800lb to 1000lb of force. Now what is 1/2" climbing line rated at new? 8000lbs, or the minimum 6,900lbs so funny how all of a sudden it's busting at 1,000lbs

Be careful with your ropes, and bull ropes etc do get beat up, threads pulled, crushed, dirty etc.