...which is nothing more than a double-line
Sheet bend, of course - and it can only be loaded in the particular way the
Sheet bend is loaded : i.e., the ends should be parallel to the axis of the knot, not perpendicular to it ( as advertised...
). Otherwise, the two legs of the
Sheet bend will split / spread... no knot tyer or not would wish to watch this !
I copy and paste a relevant post (0) :
" If I had to point out the less clever ( = most dumb ) knots I know, this so-called "
Midspan Sheet bend" would probably be the first.[ Edited :
among the firsts - I should not forget the
Shepherd s hitch , not to mention the double line
Timber hitch, advertised as : "
Timber hitch on the bight" ). And I am really sad that the knot tying community has been parroting this ugly tangly over and over again, all those years ! We have taken a double line
Sheet bend ( you know, the ABoK # 1 ! ) and we are proud that we have managed to reduce just a tiny fraction of the required material... A great achievement, indeed ! Then, we try to conceal the fact that this tangle is working like a proper
Sheet bend only in a few of all the possible orientations and loading patters of the two lines. In particular, when the two lines are parallel to each other, and both ends of the one, at least, line are loaded, this ugly tangy reveals its true monstrous face ! However, in the web sites where the beast is presented / advertised as a beauty, one will not see even
one picture of a loaded knot : perhaps because it would have been difficult for us, the lesser knot tyers, to follow the segments of the ropes, the owners of the sites are kind enough to present only sketches of "exploded", loose knots...
As a bight-to-bight bend, the "
Midspan Sheet bend" behaves as a proper
Sheet bend, indeed - and this is the only case when it deserves this name. In this particular role, and in this role only, it is quite satisfactory, and I believe that a more complex bend, like the ones presented in (1), would seldom be needed and required.
However, when each of the two bights is formed on each of two parallel lines, the ex-Sheet bend will hold only if it is lucky enough to squeeze every last tiny fraction of friction generated within its deformed, ugly body. The tensile forces which should help the bights to close and embrace each other, work in the exact opposite, destructive way : they tend to open them up, and to tear them apart. Especially the poor bight with the uncrossed legs, is suffering a lot in this
spagato [ = splits : (2)] it is forced to perform, and only a miraculously balanced distribution of tensile forces would alleviate its pain - but there are no miracles taking place in real life recently, I am afraid. One would expect the utilization of one or more nipping loops, to squeeze a double line going through them, so the loading of the lines would become beneficial, and not catastrophic, for the connection. When one has the Gleipnir, the Bowline, the Sheepshank, the Captain Mullin s knot, all those knots that
utilize / take advantage of the loading of the ends, he can not be satisfied with this tangle which
suffers from it.
The problem is : What can we do ? There are things we simply are not able to do with knots, and we will never be. The variety of possible rope-made mechanisms is condemned to be limited, if the allowed complexity of them is also limited. Will we ever fly using a simple knot ? I doubt it !
Now, should we use an ugly tangly, when we have not anything else ? That is a matter of personal taste. Personally, I will not. I respect knots, and I do not like to see them suffering, trying to do things they simply can not do, given the limits of complexity allowed to them. I would better chose another method, or tie a much more complex knot, but I will not use an ugly tangly that "would simply do the job" - provided the loading will not be heavy, and we will keep our fingers crossed !
Simplicity is a great thing, but it should not be used as an excuse, in situations it simply does not apply ! I myself do not know any simple TIB knot that would hold two lines together, independently of the loading pattern of the four limbs. This "
Midspan Sheet bend" is a decent bight-to-bight bend, and nothing more. Its name is deceiving, and has mislead people to believe that it is the miraculous simple medicine that cures all diseases... It does not. Instead of trying to figure out the few applications where this knot will work, (simply because any tangle can work, if it is loaded in a particular way and with light enough loads...), I suggest we try to find something better, even if this will require a much more complex knot. Parroting will continue, that is for sure, because it is such a successful strategy of nature. However, imagination and creativity should continue, too. And if it is proved that there is nothing else satisfactory enough, there will be always the option of a line-to-line mechanical fastener !
"
0.
http://igkt.net/sm/index.php?topic=4432.msg28042#msg280421.
http://igkt.net/sm/index.php?topic=3640.02.
http://en.wikipedia.org/wiki/Split_(gymnastics)
