Need assistance with these Eye knots (History)

[alpineer]

I've removed (finally) all references to "blood" in my images and edited some posts from #76 onward.

[xarax]

   Since the presentation of the Tresse coiled S.Part bowline (0), I came to appreciate more than before the power of a "nipping structure" made from multiple nipping turns squeezed upon each other by an external diagonal element. If one does not want to use a double collar ( which is the strategy I recommend ), a very tight, self-locking nipping structure is the best he can have, in order to secure the second leg of the single collar as effectively as possible. In particular, I have tried again the humble Triple bowline ( = three nipping loops ) ( shown in the attached picture ), and I had seen that its long "nipping tube" becomes very tight, indeed, while it still remains easy to untie. Re-tucking the Tail End through the collar, on the one hand we obtain a wider, rounder collar, and on the other we turn the bowline into a TIB one, for whatever this may mean for our application.

0. http://igkt.net/sm/index.php?topic=5357.msg36132#msg36132
1. http://igkt.net/sm/index.php?topic=5357.msg36416#msg36416

[xarax]

  The same nub, used in an "Eskimo" bowline.
  The "higher" turn does not remain in contact to the middle one, so I guess that the helical "nipping tube", squeezed by the direct continuation of the Standing End, would not be able to "lock" around itself so tightly ?

[Tex]

Hi xarax.  I "disagree" with your interpretation of the eskimo version.  For the eskimo version you have to reverse the direction (top to bottom instead of bottom to top) of the coils relative to the standing end when you first make them (or by reverse reeving if you prefer to think of it that way).  Relative to the collared line though, the direction of those coils will still be the same and you'll get a knot that has the original structure, but eskimo.  The turns do not separate.

That's an objective fact, not a subjective similarity.  If you pretend the outgoing eyeleg is the standing end and pretend the standing end and in-going eye legs are the loop legs, it then is exactly the same knot, coiled the same direction, as the standard form.  Yours is not. 

This change in coil direction is always required when switching from the standard bowline to standard eskimo bowline too. 

[Tex]

Simply put: IMO, eskimo variations should be defined as having identical knot parts to their standard variations.   

If you cut the loop and rejoin the appropriate legs/ends, you should have the exact same loop / loop knot.  Yours does not have this property.  I suspect it was just a mistake on your part.

[Tex]

Now regarding the function of these knots.  It seems to me that multiple nip turns are more "useful" than multiple collars. 

To me, there is a ratio of collar tension to nipping power, and that translates to a ratio of collar tension to load.  As the load gets stronger the nips nip tighter but the collar requires more tension to hold the nip straight and closed.  I guess if there is any (non security related) improvement needed over a standard bowline it would be to increase the ratio of nipping force to collar tension, thus reducing strain at the collar.  It's not clear to me that a standard bowline really needs any improvement in that sense, but ok.

True full multiple collars as in a True Double Bowline [1] or similar[2], reduce the tension per collar, but not directly the total collar tension.  They should also increase the nipping force by way of having more load carrying lines actually nipped, and so this, in the ratio, reduces collar tension.  They do soften the bend of the standing end around the collar for what it's worth.

Fake double collars[3] also have the softening effect, and they create a little of their own extra nipping force, friction preventing slippage around the collar and thus adding to the force of the nip to prevent slippage of the tail (or slippage between multiple loops) but I guess this is much smaller than the added nipping force of the nip for true double collars.

However, more nip turns should directly multiply nipping force too (since collars should be relatively less tense anyway) AND they provide more torque on the nip (because the nip is longer) to keep it straight and closed, thus reducing (I guess significantly) needed collar tension.

So, I'm not at all sure that I agree that improving collars is better than improving nips.  I would think we should aim to minimize the importance of collars by decrease the tension required of them and by nipping better to prevent slippage.

On the other hand, I'm not moved by any of it if it doesn't provide more slack security.  The bowline is already good enough under load isn't it?  Why complicate it?

 
1. http://igkt.net/sm/index.php?topic=5385.msg36532#msg36532
2. http://igkt.net/sm/index.php?topic=5385.msg36534#msg36534
3. http://igkt.net/sm/index.php?topic=5385.msg36008#msg36008

[xarax]

   The double-collar, TIB version of the Triple Bowline.
   Nice knot !

[Tex]

@xarax

I think what threw me off was not word "an" but the reference to the same nub.  I can hardly see how those are the same nubs.  They are tied in a similar way, but they end up as completely different nubs.  Of course that was sort of the point, so sure. Still I think it was worth clarifying that one was certainly not THE eskimo version of the other.

Ok, so in this thread by adding collars you mean a bottom collar in addition to the top one. 

   The double-collar, TIB version of the Triple Bowline.
   Nice knot !

In your last post, I have no idea what you mean by double collar.  All I see is the usual and obvious retuck that makes any simple (single nipped, double nipped, tripple nipped, cow hitch nipped, pretzle nipped, etc) bowline TIB. I don't see any double collar. 

[Tex]

Ok, well I now I understand what you mean anyway.  However I don't see this collar as having anything at all like the functionality of the usual collar.  The one tail end of this collar is not well nipped and does little if anything at all to stabilize and close the nips.   It does a little for slack security, but I guess isn't so great at that either.  To me, mostly all it does is result from tying this in a bight, in other words it just exists.  That doesn't earn it the name of collar to me, but if we're just describing geometry, I suppose, well I still don't like it but definitions are just definitions then.

[Tex]

If I didn't mess up, the change in tension supported by friction for a round turn is simply:

dT/d_theta=T*mu

for coefficient of friction mu, instantaneous tension T and a small angle d_theta.

So this is of course what you mean by turns absorbing tension.  This can be integrated to give a supportable tension difference between two sides of a turn, but this math breaks down at zero tension and the whole rope falls off the turn, which of course is why the tail has to be pinned somehow for a hitch to work.

This tail "collar" (turned tail) needs not support any tension because as you correctly say the nip needs no improvement and the bowline can and will support all the load without allowing any tension through to the tail.

So I fail to see how this collar is doing anything at all, and thus why you call it a collar.  Under load it is useless.  It is a decoration.  I suppose we can think of it as a decorative collar, but I don't see the point.  It's just a passive tucked piece of slack rope.

Honestly though, I find these bowlines kind of boring.  Two turns, ok.  Three.. obvious extension. Useless?  Maybe not, just not too exciting, still something to chat about though.

[SS369]

Hi All.

I believe a reminder to be fair to the original post is in order.
We are diverging once again, even though the conversation is interesting, we are veering off topic.

SS