Man-Harness Knot

From another thread pdqdl posted this:

pdqdl said:

...
By the way: for that mid-line knot, try the man-harness knot. Putting a load on in the middle of a line is what it is designed to do, and it unties easily after heavy loading, unlike the alpine butterfly. Someday I'll get somebody here at AS to try it out...

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AND THIS:
http://www.arboristsite.com/showpost.php?p=1187344&postcount=37

Ok, next heavy rigging job where I need a mid-line loop, I'll try it.

Maaaybe ... we could get moray to test it.

Thanks for the support Jack!

For those of you who haven't followed the previous threads, here is how this knot works best:

Tied midline, it is the best thing going for fixing a pulley (or just using to tension the rope through the loop itself) and pulling. This presumes that at least one end of the rope will have a load on it, and the loop will also be sharing the load. So long as the loop is kept loaded, this knot is bulletproof. Take the load off, it is easy to untie.

If you intend to pull on the two standing ends, and leave the knot itself without a load, you would do better with an alpine butterfly. The man-harness knot will unfold a little and creep down the loop until it chokes down on the bight.

Testing the Knot

There are two conformations of the knot that need to be tested. In the photo I am calling them A and B. In A it is clear that the standing part (arrow) passes through one bight and then wraps the loop. In B the path of the standing part is more difficult to follow, so I traced it with the red line. It passes through 2 bights and then forms the loop.



I tested two identical A's against each other and then two identical B's against each other. Strengthwise there was very little to choose between them: the A version broke at 4546 lbs., and the B version broke at 4442 lbs. By comparison, two bowlines broke at 4406 lbs. in the same rope, Yale Blaze (nominal strength 5600 lbs).

But A and B were otherwise quite different. The A version never cinched down on the pin, and the survivor A was easy to take apart. The B versions both cinched down on the pin after a few hundred pounds, and the survivor B was completely impossible to take apart. Both versions ate a small amount of the tail, probably less than an inch, but became quite stable as the load increased.

The picture below shows the version B survivor. Because of the cinching action of this version, the loop end of the knot is not available as a site for working the knot apart. The only remaining site, where the standing part and tail emerge together, simply won't allow it.

I am not sure if you have been tying that correctly. There is only one configuration for the knot (properly set by pulling on both ends opposite to the loop), but it can obviously be pulled from either standing end alone, which would be expected to have different performance since the knot is not symmetric. When used properly, it is used as a mid-line knot where both standing ends have some load on them, as well as the loop. I have never been able to bind it so that it did not untie, but maybe I was just lucky.

Your testing looks like this was used as a terminal end loop, which isn't exactly how it is meant to be used. I am surprised that it tested as strong as the bowline in any configuration, as I consider that knot to be the gold standard for terminal loops.

As I have stated elsewhere:

The manharness is poorly suited for heavy line pull on both standing ends of the line with no load on the loop, but has almost no tendency to bind up when heavily loaded on the loop against either (or both) standing ends of the line. Best suited for pulling the loop with heavy loads parallel to the line, if ease of untying is anticipated. Faster to tie, but requires dressing properly to hold well.

If you load this knot without properly setting it, it can choke down, as you discovered. Since I have never tested this knot to destruction, it could be that one of the standing ends will have a greater tendency to choke down than the other when it is taken to the limit of the rope.

So far, that has never happened to me. Prior to going "new-school", I used this knot as my point of attachment for my climbing line, so I have a great deal of experience with it, as well as confidence in it.

pdqdl said:

... There is only one configuration for the knot (properly set by pulling on both ends opposite to the loop), but it can obviously be pulled from either standing end alone, which would be expected to have different performance since the knot is not symmetric...

Your testing looks like this was used as a terminal end loop, which isn't exactly how it is meant to be used...

Click to expand...

I probably could have worded my post better. By two configurations I was referring to the two possible and different ways of pulling against the loop. As you say, the knot is not symmetric. Even though there is only one knot, there are right- and left-handed versions of the knot and I believe I inadvertently tied the A's one way and the B's the other.

Since it is a loop knot, not a bend, I assumed we wanted to test the loop, so I tested both "configurations" by pulling against the loop.

I did dress the knots as best I could before testing, so I am pretty sure the version that cinches down will always do so under heavy load, and that it will be impossible to untie after a heavy load. The sweet version is the "A" version, and it behaves exactly as you describe.

I like it--it's a nice little knot. Especially midline, where you can't tie the bowline, this would be the non-cinching knot to use.

Well your testing has once again proven useful to me! I had never loaded the wrong leg enough to cause slipping.

I can see how it might become important to tie the knot so that the "A" leg has the greater load on it. Maybe I have just been doing that all these years by pure luck... now you are going to make me go do some checking.

To tie off to chords and/or the pendant's or other crane parts ..this is a knot we use ..
Personally Im a big fan of lifting lug's..

SINGLE-JACK said:

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Ok, next heavy rigging job where I need a mid-line loop, I'll try it.

Click to expand...

pdqdl said:

Well your testing has once again proven useful to me! I had never loaded the wrong leg enough to cause slipping.

I can see how it might become important to tie the knot so that the "A" leg has the greater load on it. Maybe I have just been doing that all these years by pure luck... now you are going to make me go do some checking.

Click to expand...

Well ... as promised, I tried it, today. Used the "'A' leg" man-harness mid-line loop on large pull down. I used 1/2" Tree Master in the rain - which tends to bind any knot. During wrap-up the knot was easier to untie than any mid-line I've ever used. However, I do believe that Moray's work that identified the necessity of using the "'A' leg" was critical to the successful outcome.

Thanks to pdqdl and Moray for adding another useful tool to my kit.

- Jack

Alpine Butterfly Knot

another good one is the Apline Butterfly Knot..... http://www.animatedknots.com/ Go to climbing knots...

Someone please change the name of this knot

Maybe I am a little phobic but Man Harness knot kinda brings up images of some dude tied up in leather chaps and nipple rings. Someone find a new name for it PLEASE

As I recall from an earlier post by JPS, this knot got it's name from long strings of men dragging cannon though the woods. The battle of New Orleans with Stonewall Jackson comes to mind, but I'm just running on memory.

Imagine angry, battle-ready Federal soldiers dragging 2000 lb cannon through the swamps with no roads, no baths, poor food, and no insect repellent. Then suggest to that collection of fine gentlemen that they put on their leather chaps and by the way, boys...we got some nipple rings we want you to try out! The response to THAT suggestion would be funny to watch!

I learned this knot in Boy Scouts as the "pioneer knot". It was used to take a simple rope, tie mid-line, then go around the base of a tree and back to the knot. Used as a simple pulley. it can be nested several times to give quite a bit of mechanical advantage, despite all the friction. I have done that trick MANY times to pull a tree over. I rig it faster than you can go to the truck and get your pulleys and slings. Of course, there is no real comparison when friction is reduced by the use of a real pulley.

Stihl-O-Matic said:

Maybe I am a little phobic but Man Harness knot kinda brings up images of some dude tied up in leather chaps and nipple rings. Someone find a new name for it PLEASE

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OK, OK!!! ... but PLEASE, do not paint that mental image again!!!
DEAL? lol ... it's the OTHER definition of harness!!!

"153. The ARTILLERY LOOP, also called Man-Harness Knot and Harness Loop, is tied in the bight of a rope. It is used for a hand- or shoulder-hold in hauling field guns into position, and also in assisting horses either in uphill work or when mired." - THE ASHLEY GOOK OF KNOTS, Clifford W. Ashely, 1944

BTW - If I've got it right (check this Moray & pdqdl), the "A-side" is on the right of ABOK 153.

SINGLE-JACK said:

OK, OK!!! ... but PLEASE, do not paint that mental image again!!!
DEAL? lol ... it's the OTHER definition of harness!!!

"153. The ARTILLERY LOOP, also called Man-Harness Knot and Harness Loop, is tied in the bight of a rope. It is used for a hand- or shoulder-hold in hauling field guns into position, and also in assisting horses either in uphill work or when mired." - THE ASHLEY GOOK OF KNOTS, Clifford W. Ashely, 1944

BTW - If I've got it right (check this Moray & pdqdl), the "A-side" is on the right of ABOK 153.

Click to expand...

THANK YOU you saved me a lot of suffering

SINGLE-JACK said:

...BTW - If I've got it right (check this Moray & pdqdl), the "A-side" is on the right of ABOK 153.

Click to expand...

Yes it is. But when I tied this a few dozen times in some stiff prusik cord just now, I realized things are a bit more complicated than I realized.

Both the A and B legs can produce a slip knot or noose. If you never dress the knot to look like Ashley's drawing, but instead pull on the leg you want just as you form the loop, you will pull the knot into a slipping conformation. I found a consistent way to get the right result is to form the loop and dress the knot by pulling both legs together in one hand against the loop in the other. Then pull the legs against one another. This gives you Ashley's shape. Now pull the A leg against the loop and you have the non-slipping golden conformation.

This is a real chameleon knot if you're not careful!

I have a question for Moray -- if knots decrease the strength of a rope by creating tight curves which stress the rope fibers in a non-uniform manner then how large (in rope diameters) does a pin or pulley need to be to allow the rope to approach its nominal rating?

davej said:

... does a pin or pulley need to be to allow the rope to approach its nominal rating?

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I don't have any first-hand knowledge about this, but I've read 8 or 10 diameters are recommended to preserve most of the rope strength. 8 diameters would surely beat any knot. How much the rope would be weakened by an 8-diameter bend will also certainly depend on rope construction. This is just a guess, but I expect any rope would keep at least 90% of nominal strength around an 8-diameter bend.

How about the spliced end of a rope on a carabiner vs. a thimble?

Carabiner vs thimble won't matter because the rope that forms the eye only sees half the tension of the main rope. The biner or thimble would have to reduce the strength of the eye rope by over 50% before that could become the weak link. The weakest spot of the system is almost always right at the end of the splice bury.

This would almost always be true for a loop knot as well. I don't remember any of my knot tests breaking in the loop.

The value of a thimble in a spliced eye would be to reduce wear in the eye. Now if you're talking about a really hard-laid 3-strand that hates to bend, maybe the bend around a caribiner in a spliced eye could be the weakest spot, but I doubt it.

While dwelling on knots today, I was trolling through my Ashley Book of Knots. He uses a number of different icons to represent different traits of different knots.

For "easy to untie", he uses a picture of a pretzle; this is a curious choice since the startup position for tying the manharn...ahem,...Artillery loop is also a pretzle shape. I wonder if Ashley picked this icon with this knot in mind, since it's best trait is it's ease of untying?

moray said:

Carabiner vs thimble won't matter because the rope that forms the eye only sees half the tension of the main rope.

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Oh, good point. I'm not thinking clearly. Ok, how about this then... rope is tied to itself with a Blake's to form a loop? That ought to have a minimum curvature.