Three wrap prussik, Valdotain Tresse, Schwabisch, Distel, Blake?s Hitch, autoblock, etc.
These friction hitches are essential to the sport climbing and arborist industries, yet for all of their various pros, all of them have the same impurity. The existence of this impurity has resulted in marketability of mechanical devices generally referred to as mechanical prussiks, zigzags, etc. These mechanical devices come with added intricacy and costs.
The industry has worked around this impurity for so long that it probably doesn't expect a solution.
In the primary load direction, these friction hitches are lifesavers.
In the secondary direction, they snag, bind, grab, stop progress, and cause headache. They nearly all require fingers to loosen the hitch to allow the rope to slide freely.
To my knowledge no friction hitch exists that is a a pure prussik that is full friction in one direction but frictionless in the other.
You could spend hundreds of dollars on progress capture devices and mechanical rope grabs like petzl micro traxion, tibloc, kong duck, etc to solve this problem.
Heres my attempt at a solution.
Shown with yellow 5mm accessory cord and a Bluewater VT prussik on green 9mm canyonator rope.
Of course there is some friction, however the backside leg of the rope can be tugged and slides easily through the prussik. No need to touch the prussik.
My solution here has two parts: part one is the typical three-wrap or three round turns, part two is what I refer to as a backstop to nudge the friction turns loose. The backstop part looks like this:
I am looking for suggestions how to simplify this backstop part. The part has two practical characteristics: it has a lasso turn which is a single turn around the rope essentially a fixed loop, and the second characteristic is that load bypasses this lasso directly into the three friction wraps.
It needs careful dressing such that the three wraps are adequately snug to engage, and the lasso turn is sufficiently loose on the rope.
A pure unidirectional prussik could solve current problems and change the ballgame with current rope ascending techniques in caving, rock climbing, canyoneering, etc. It could also be used as a fall preventer on a fixed line, for example you scramble up rocks and the hitch slides upward along a fixed rope, protecting you from downward movement (aka fall).
It could also be used as an arborist hitch, or on an arborist lanyard for positioning. When your hands are occupied, being able to grab the tail end of a loaded rope and pull slack through a friction hitch would be indispensable.
