I have been interested in the numerous friction hitches we have at our disposal. Claims are made for each including the amazing claim made for the Icicle Hitch that it can hold fast to a tapered spar.
Examination of the various hitches showed that they tended to have similar conformations. They would have a load application section, a set of coils for grip and an anchor. Generally the anchor is formed by taking a line from the anchor, down, across the coil to clamp the the anchor and the coils in place, to the load tension point.
Generally the limitations of these various knots stemmed essentially from the clamping line pulling the whole knot forward and failing it.
The knot presented here was designed purely from principle and to this end, if the knot has not already been documented and classified, then I would like to name it the "KC Hitch" - in honour of the person who tries relentlessly to educate us all into the world of knot leverage. This knot is based on two principles. The first is the Power of Wrapped friction law perfectly explained by Roo_Two on his web page
http://www.geocities.com/roo_two/friction.html . This law describes how a small holding force is increased exponentially with the angle of contact - roughly to the power of three times the coefficient of friction for every complete turn.
The second principle is that of Angled Leverage - continuously promoted by KC. This principle shows us that small tangential movements of a line away from the shortest path have a huge mechanical advantage approaching infinity as the line is first starting to be moved away from the shortest path. Most of us will have utilised this principle, tightening a load by pulling sideways on a rope or by standing on a towline to budge an obstinate load.
Both of these principles are at work in all of the documented friction hitches, however, in designing this knot the principles were used to create the knot form rather than happen by accident by trial and error tying of cord. As a consequence, this friction hitch should be approaching the optimum for friction hitch abilities. However, only stringent Peer Review and in field use will show if theory alone has given us a better friction hitch.
The Design Stage.The Wrapped Friction Law can only
amplify a gripping force, so any use of this law must start with a finite gripping point, so the knot must have three sections or functions:-
Part 1 : The anchor - this will provide the embryonic gripping force which will be amplified by the coils.
Part 2 : The gripping engine - this will utilise coils to exponentially amplify the anchor grip to the level needed to hold the object and transfer all the working force into the held object.
Part 3 : The force engine - this will allow the applied force to be transmitted into the knot, to tension it and to allow for surface geometry and movement of the knot.
To start then, I used the best gripping anchor I know - the Constrictor. I tied a constrictor onto a length of dowel and yes it was able to generate a small gripping force which could be fed into an amplification coil. Note, this is friction
around the dowel NOT along it. The line from the constrictor was then wound around the dowel and exactly as predicted, the gripping force rapidly amplified within just a few turns. Even tying this construction on a glass bottle it was easily possible to add turns until the small holding force from the Constrictor had been amplified to a level sufficient to grip the glass.
Of course, this is grip tangential to the dowel and this hitch must create grip in line with, i.e. along the dowel. This was easily achieved by driving a pin into the dowel and turning the cord 90 degrees around the pin so that the gripping force now ran along the dowel. Of course, we cannot rely on banging pins into object just to make our knots work - this knot would have to provide its own means of turning the direction of grip through 90 degrees. The solution is of course an easy one. The second line coming out of the constrictor was simply wound in a counter spiral through the first and the two ends joined. In this manner the two coils work together to turn the gripping force through the necessary 90 degrees.
Finally the force or tensioning engine. As the loading force is applied to the knot, the first turns start to open up - concertina fashion. In doing so, the cord is forced to lengthen and the force of creating this stretching is transmitted through the cord back into the knot itself. This linear tensioning of the knot cord massively increases the coefficient of friction and is transmitted right back to the anchor Constrictor further tightening it and increasing the anchor grip being made available to the gripping engine coils. The more elastic the cord is or in cases of very low friction, several of the turns might be forced to open in order to generate sufficient line tension within the knot.
And there you have the prototype "KC Hitch". It is highly functional, it can grip glass even with Spectra cord and it can hold firm onto a taper. There is a limit to the angle of taper this knot can hold and this limit happens when the diameter of the taper narrows faster than the line extension caused by opening the loops. When this angle is reached, the knot will never hold and will always simply run off the taper. However, at angles below this critical angle, line tension is increased as the loops open up and given sufficient turns, any surface can in theory be held.
OptimisationThe prototype "KC Hitch" is highly functional, but as a working knot it is a real pig to tie and so is unlikely to ever move into mainstream use. It was notice during trials with various cords and binding surfaces, that movement of the last two coils rarely occurred and that the tensioning effect caused these coils to lock tightly onto the load surface. This meant that the coils could act as their own anchor thereby dispensing with the need to tie a Constrictor around the load. This proved to be the case and led not only to a simplification in the construction of the knot but also to an extremely simple method of tying it.
Here then is the final field ready "KC Hitch"
Take the line and start with a working length sufficiently long to make the required number of turns around the load. For high friction loads four is sufficient for low friction (glass, polished wood etc) eight may be necessary.
Hold the cord against the load with your thumb

and wrap the working end around the load in an open spiral ( say three or four turns while you experiment with this hitch).
Then start wrapping the cord back over the first spiral so the cords cross front and back of the load.
When you get back to the start, tie the ends together using whatever knot you prefer, even the Reef will do here as its only function is to hold the ends together.

slide the coils up together and take out the slack.

Apply tension to the load and the first coils will open and tighten up the knot. If there is a lot of slack taken up, then close up the loops again and remove the slack before reapplying the tension.

The objective is to have at least the last two turns (the anchor turns) remain closed under full load conditions.
ObservationsThis knot uses leverage to apply tension and that leverage is very powerful. I have seen samples where 500# Dynema has bitten into the surface of a glossy dowel - it did not slip, but it sure bit in. As a consequence, you need to be sure that you are using rope or cordage of sufficient strength to take these loads. This needs to be considered as a potential weakness of the knot as the leverage is capable of amplifying the applied load to levels in excess of the breaking strain of the cordage used. You might find it advantageous to tie the knot to the load in one cord and then use a different rope to haul with.
The second observation may serve to stimulate future studies, and that is that there is a definite relationship between cord diameter a load diameter and how many coils open during the loading phase.
ConclusionSo there you have it - is it a new knot? Does it work in all applications you test it in? What is your considered opinion of its structure and working parts? Do you feel that the analysis and process was flawed in any way? When does the knot not work and what safety concerns do you have?
Is it now possible for members to give this knot a critical Peer Review as this is surely the prime value of the combined expertise of the people gathered around the IGKT.