If a double ( or even a triple ! ! ! ) fisherman s knot can fail to hold a slippery Dyneema line, it is reasonable to search for more complex solutions. Moving one lever up from the single, double, triple etc. overhand knot, we can use a fig.8, fig.9, fig.10, etc. knot. In this thread I show the basic fig.9 stoppers which can be used at the ends of a fisherman s knot-like "interpenetrating Standing parts" bend lines, instead of the overhand-knot-based stoppers.
We have recently seen that, in a knot tied on Dyneema line, many constricting round turns are not as efficient as few sharp U turns and/or few right angle crossings. We should rather increase friction by increasing the local deformations of the lines at their points of contact, rather than by increasing the forces those lines are squeezed on each other.
A second issue is the easiness we can tie more complicated than the usual simple knots. If the tying of a complicated knot requires more than two-three tucks, it becomes very difficult to remember how to tie, and very difficult to inspect if it was tied correctly in the first place. Also, the time needed to tie such a knot is considerably longer, and the chances there will be some mistake during the tying procedure are multiplied.
A third issue is the volume of the knot. In many applications, if we have to use complex knots of some considerable volume, it is better if this volume is distributed along the axis of the knot, in elongated bodies, than along large cross sections, in spherical bodies. A rule of thumb I use is that a sleek knot should present cross sections on planes perpendicular to its axis not much wider than 4 rope diameters.
All those three things combined led me to examine the chance the Fig. 9 stoppers and their relatives would be more secure, when tied on Dyneema line, than the double overhand knot stoppers ( or even the triple overhand knot stoppers ? ).They require two, only, tucks, and in their 8-shaped form they offer those two clearly formed openings through which on can pass the end of a second line very easily, in one stroke. What might be even more important, is that when the one knot will be squeezed on the other, those stoppers will "fold" and the turns of the lines within their nubs will be forced to become sharper. Good news for the taming of the Dyneema shrew !
As it should have been expected, the three possible 8-shaped fig.9 stoppers are grouped in two classes. The less symmetric forms, based on the symmetric closed 6_1 and 6_2 knots, fold differently than the symmetric one - based on the asymmetric 6_3. (1).
1.
http://igkt.net/sm/index.php?topic=4719.0 
