Relative security of multiple-loop knots

[erizo1]

I'm wondering about the relative security of some of the multiple-loop knots. I just discovered the French bowline, which I like better than the bowline on a bight because the loop sizes can be adjusted without loosening the knot, but I suspect that it is not quite as secure. How do those two compare to each other, the triple bowline, and to the figure 8 variations (double, equalizing)? Again, security is my primary point of curiosity.

[X1]

   The only way I know is to actually try / test those knots against each other, in a tug-of-war arrangement, and see which slips more !  To achieve this, you have to tie them using small diameters on the most slippery material you can find, dental floss, oiled monofilament line, HDPP fishing line, you name it. Also, you have to repeat each experiment many times, and keep notes about even the minor details of the experiment ( how strongly you have pulled the ends to dress them, etc). IFF you are lucky, you will get a vague idea after some time - otherwise you should run serious laboratory tests, on the same ropes you use, that would probably involve universal testing machines, high loads, etc. Security/slippage tests are even more complex to perform than strength tests - which are already very difficult !

[roo]

I'm wondering about the relative security of some of the multiple-loop knots. I just discovered the French bowline, which I like better than the bowline on a bight because the loop sizes can be adjusted without loosening the knot, but I suspect that it is not quite as secure. How do those two compare to each other, the triple bowline, and to the figure 8 variations (double, equalizing)? Again, security is my primary point of curiosity.

Slack shaking and other motion, NOT what X1 describes, is what usually causes security issues with knots in rope.  With multi-loop knots you have the added concern of what happens when the knot see various or unusual load configurations (security & capsizing stability), whereas with a single loop, the number of load configurations would be much reduced.

http://notableknotindex.webs.com/knotfaq.html

What's your application?

[erizo1]

What's your application?

My interest in this kind of knot is prospective at the moment (although in the future I hope to take up rock climbing, so my working scenario as I consider these is clipping into multiple anchors). I'm basically in the process of "collecting" knots, and I want to have one for each type of application that I would consider my most trusted, or go-to, knot. Most often I have a situation arise and then search for the best knot for it. I haven't needed a multi-loop knot yet, but I'm sure one day I will.

I posted here because my reason for learning knots is purely practical: I find them useful, and I want to learn the knots that are most useful for various applications. Security is perhaps the consideration I value most; I want knots that can take care of themselves and don't need backing up or protecting from certain circumstances (e.g., I love the zeppelin bend and alpine butterfly loop for this reason).

I've learned a bunch of multi-loop knots; some I like because it's easy to adjust the loop sizes after you tie it, some because I like how they're tied (I want to shake the hand of the man who thought up how to do the bowline on a bight, I think that's tremendously clever). But there are a number that do basically the same thing, and I'm looking for one to prefer over the others. I've tied them all in different types of rope, I recently got a length of PMI 11mm static rope to work with, which is much thicker and stiffer than anything else I've used, and tying a French bowline in that was instructive, but I wanted to get other people's take since my experience is limited.

[X1]

in the future I hope to take up rock climbing

  Please, never, ever, even think about leaving a not-functioning knot still tied on a climbing rope !
  People have died because of this grave, lethal mistake !
  Learn about safe, post-eye-tiable, bowline-like loops that are untied in one stage.
  The best presentation of safe bowline-like loops is at :
http://www.paci.com.au/downloads_public/knots/Bowlines_Analysis.pdf
   
 

[erizo1]

X1, thanks for that PDF. The knot labeled "End Bound Single Bowline" is particularly interesting to me (obviously not as a double loop, just in general). I like the yosemite bowline; this seems like an even more secure knot (I can't imagine how you would shake one of these loose by accident), and I just think the structure of it is really cool.

[roo]

What's your application?

My interest in this kind of knot is prospective at the moment (although in the future I hope to take up rock climbing, so my working scenario as I consider these is clipping into multiple anchors). I'm basically in the process of "collecting" knots, and I want to have one for each type of application that I would consider my most trusted, or go-to, knot. Most often I have a situation arise and then search for the best knot for it. I haven't needed a multi-loop knot yet, but I'm sure one day I will.

I posted here because my reason for learning knots is purely practical: I find them useful, and I want to learn the knots that are most useful for various applications. Security is perhaps the consideration I value most; I want knots that can take care of themselves and don't need backing up or protecting from certain circumstances (e.g., I love the zeppelin bend and alpine butterfly loop for this reason).

I've learned a bunch of multi-loop knots; some I like because it's easy to adjust the loop sizes after you tie it, some because I like how they're tied (I want to shake the hand of the man who thought up how to do the bowline on a bight, I think that's tremendously clever). But there are a number that do basically the same thing, and I'm looking for one to prefer over the others. I've tied them all in different types of rope, I recently got a length of PMI 11mm static rope to work with, which is much thicker and stiffer than anything else I've used, and tying a French bowline in that was instructive, but I wanted to get other people's take since my experience is limited.

Double loops tend to use an huge amount of line, don't get much testing, and due to their complexity they often tend to have hidden vulnerabilities.

A cleaner, more reliable route would be using a separate line for your two anchors and in the middle of this line a clove hitch can be made over a carabiner to equalize as needed.  A Pile Hitch may be used as a more jam resistant alternative to the Clove.

All other connections can be made with standard, tested, secure hitches or loops:
http://notableknotindex.webs.com/gnathitch.html
http://notableknotindex.webs.com/waterbowline.html
http://notableknotindex.webs.com/zeppelinloop.html

If you don't want to use a carabiner at the bottom of the V with a clove or pile hitch (the easiest option for checking), you could use your main rope to form a friction hitch (like Blake's Hitch) around the bottom of the V.    That's easy equalizing and it will save you yards of rope in comparison to a double loop.

Another substitute for a double loop is a Butterfly Loop.  The first anchor is connected to the main loop, while the second anchor is attached to the free end of the loop with a secure hitch.

[roo]

I like the yosemite bowline; this seems like an even more secure knot (I can't imagine how you would shake one of these loose by accident),

Windy day comes to mind.

[roo]

in the future I hope to take up rock climbing

  Please, never, ever, even think about leaving a not-functioning knot still tied on a climbing rope !
  People have died because of this grave, lethal mistake !
  Learn about safe, post-eye-tiable, bowline-like loops that are untied in one stage.
 

Despite your alarmism, by far the most popular rock climbing loop knot is the Figure Eight Loop.  So... where are all the reports of deaths from this loop? 

[erizo1]

I like the yosemite bowline; this seems like an even more secure knot (I can't imagine how you would shake one of these loose by accident),

Windy day comes to mind.

I was referring to the End-Bound Single Bowline. Is that the one you meant could be shaken loose on a windy day, or were you referring to the yosemite bowline?

[roo]

I like the yosemite bowline; this seems like an even more secure knot (I can't imagine how you would shake one of these loose by accident),

Windy day comes to mind.

I was referring to the End-Bound Single Bowline. Is that the one you meant could be shaken loose on a windy day, or were you referring to the yosemite bowline?

For its complexity, the yosemite bowline doesn't offer a great deal of increased security.

Now, enough slack shaking for a long enough period of time will do in just about any knot in stiff climbing rope.  The best way to get a feel for this is to try this shaking or flogging yourself and see how long it takes you to make a knot spring open.

What can make things harder is that as your rope gets bigger, it becomes increasingly difficult to get a good initial set on the knot to keep things compact.

P.S.  I thing the emphasis on preknotting (or not) is not very relevant.  The overall time it takes me to tie and adjust a Zeppelin Loop is less than it takes for just about any other higher-security loop.  And of the many hundreds of loops I've tied over the past few years, the number of times the Zeppelin Loop's method of tying would be inconvenient is about zero.

The bowline is very fast to tie and I'll use it just as long as I don't need much security.

[erizo1]

P.S.  I thing the emphasis on preknotting (or not) is not very relevant.  The overall time it takes me to tie and adjust a Zeppelin Loop is less than it takes for just about any other higher-security loop.  And of the many hundreds of loops I've tied over the past few years, the number of times the Zeppelin Loop's method of tying would be inconvenient is about zero.

I agree with you, tying that initial overhand knot has never bothered me. I keep wanting to find a knot that's super secure like the zeppelin loop but not as awkwardly lined up with the standing part, but really that's just aesthetics, and when my life is on the line, aesthetics don't matter. I'm impressed with the zeppelin yet again when I tie it in the large climbing rope. All kinds of daylight comes through when it's tight, and it still just won't budge.

I'll worry about aesthetics when I'm doing non-critical things around the house :-)

[roo]

when I had tried to tell him SO MANY TIMES that the problem of a non-PET loop lies in the necessarily two-stage untying of it ! He just can not understand that the moment the loop is released, the attached object can move, carrying the line along with it, and the still untied on the Standing part of this line "relic", not functioning any more overhand knot, which can slip through the hands of the untyer, and be dragged away, caught up somewhere, etc...
   KnotGod, help me, please ! What wrong have I done, your poor servant ! 

This simply does not come up in rock climbing.  When it's time to untie your knots, it's quite easy to untie all parts of the Figure Eight Loop, for example (assuming there is no jam).  At this point in time, there is no tension on the line.

In other applications, it's absurd to think that you'll have any chance of untying an end loop while the line is under any significant tension.

[roo]

  I do not wish to post the picture of an unfortunate climber, dead on his line, hanging days from the cliff,

Still waiting for any report of deaths from the use of the popular Figure Eight Loop via "relic" hazard.  No pictures are needed.  Just one report.  I won't hold my breath.

The mooring lines are not tensioned all the time ! On the contrary, a well-tied mooring line should remain lose most of the time, and be loaded only briefly, when the waves and the tide pushes the ship from side to side. One unties the mooring loop when it is not under tension, of course ( ! ),

We've been over this before.  There's no need for a loop here at all.  Are you afraid of squeezing your mooring restraint? 

Unlike high-security loops that may require around three untucks, a high security hitch can be used that only requires one untuck.  This should make you happy, X1!

Further, if you do have constant tension due to winds or current, hitches also give you the option of release under strain.

[Dan_Lehman]

I'm wondering about the relative security of some of the multiple-loop knots.
I just discovered the French bowline, which I like better than the bowline on a bight,
because the loop sizes can be adjusted without loosening the knot,
but I suspect that it is not quite as secure. How do those two compare to each other,
the triple bowline, and to the figure 8 variations (double, equalizing)?
Again, security is my primary point of curiosity.

Let me slip in a quick & saner answer than the ping-pong
gamesmenship going on here so far.

1) What you need to test (or find assurances for, somehow) is the
knot tied in the material you expect to use (not the entire spectrum
--or just dispersed waypoints along it-- of knottable media!);
and
2) your rockclimbing concern for dbl.eyeknots is generally NOT
of slack-security (which a shake test checks) but preservation
of eye sizes when only one is loaded, other(s) slack --i.e., the
potential of *feed* of the unloaded eye through the knot.

Rockclimbers favor the "bunny ears" fig.8 eye knot for having
less vulnerability of slippage in the case of an unloaded eye.
But there are many variations & other knots that might be
employed, which aren't (well) known.

Note that twin-eye knots might be employed, where the
duplicity isn't of the eyes --clipped qua one-- but of the
ends : each end being an independently secured anchor.


--dl*
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