The (New) Supurcell Prusik Tie-in Orvel Miskiw
Most of you may have heard of the “Purcell Prusik”, an adjustable sling system that’s been known for many years, but I’m sure that very few of you use or even carry one with you while climbing (or otherwise).
It recently came to my attention that this device is still around — to whatever extent: it was mentioned in a presentation by a prominent Mountain Guide at a recent Section meeting.
The Purcell Prusik was invented about 30 years ago as a compact adjustable-length tie-in sling — also called a tether, leash, or lanyard, etc. Its basic idea needed no inventing, as all climbers live with the occasional need or want to adjust the length of anchor slings: some of our usual methods are daisy chains, adding slings, folding slings, and tieing knots: these all provide ‘stepwise’ adjustments, and we soon learn that such ‘steps’ are never quite right.
A continuous adjustment would be nicest, so you could imagine something like a jumar, Tibloc, or prusik on a cord. Kirk Mauthner of Rigging for Rescue in B.C. came up with the idea of an adjustable loop with a prusik to provide the variable length, then… it soon occurs that a prusik works best on a tight cord, so the ‘tail’ should be an active part of the tie-in, instead of tensioning only across the loop — as in a regular sewn or tied protection sling.
And so the ‘Purcell Prusik’ was born — arranged like a ‘ b ‘ or ‘p’, with one connection at the end of the stem and the other on the loop, and the loop closed by a prusik on the stem.
Hypothetically this system can be adjusted from full length (with the loop closed tight) to half length (with most of the tail absorbed in the loop), but in practice the Prusik itself takes up a significant part of the cord, and badly restricts the useable amount of adjustment in regular-length, viz., ‘short’, tie-ins. The original Purcell could have been improved somewhat by the use of a French (one-sided) prusik which would take up less space, as it always has to hold in only one direction, in this case.
The Purcell Prusik has a grass-roots appeal of using only cord (ie., no hardware), but it’s also awkward to put together — not something to be tied on the spot when wanted, but rather it needs to be assembled at home and carried as a ‘device’, and for these reasons it never gained much popularity, although some versions are actually made and sold commercially.
Commercial Purcell Prusik (left) 
When I first heard of it many years ago, at about the time of its debut, I considered it interesting, and experimented with it, but finally considered it too awkward to be practical.
At the same time, I realized that the Purcell uses essencially the same concept as my new Kinky umbilical system for ice climbing, and serves the same general purpose – but usually scaled up.
However my Kinky umbilical is tidier and frictionless, and has a greater adustment range.
I assembled a couple of the ‘Supurcell Prusik’ slings after making a bigger version of my ‘Kinky’ locking device (right), and carried one on several climbs for testing — clipped for carrying between my harness loop and a gear loop (see below) — fast and easy to transfer to an anchor or protection, and continuously adjustable with practically no friction.
Many adjustable tethers are available commercially now, for example impressive names like Rock Empire Adjustable Pip Cape Silver, Petzl Connect Adjust, Edelrid Switch, Longe Reel, Camp Swing, Fixe Manso Fave, Beal Expresso Fit, Ocun Sbea, Anchor Cape Silver, BLE XF-GP, Petzl Progress, Kong Slyde, and Camp Reel Duo. (below, right)
Supurcell as carried between harness and gear loops.
All of these appeared on the market long after the Purcell Prusik and my Kinky umbilical were developed, and I’ve never tried any of them myself, as I already had my own ‘best’ solution, but most of them are simply a locking device on a cord, which does seem most ‘to the point’, but results in either a dangling tail or a knee-catching loop, to be dealt with continually, and they are reported by users to be generally awkward or difficult to adjust.
Supurcell Prusik Tie-In
Although my Supurcell is better than the Purcell Prusik in most ways, it still lacks a pressing need in mountaineering and likely most rock climbing, where exact length adjustments are rarely needed, but still, SO convenient when they are. In ice climbing, the same concept is an amazing improvement for resting or working on protection on near- and vertical ice.
But for everyone who keeps a Purcell Prusik, and for ANY climber who’d like the convenience of a simple, frictionless, continuously-adjustable tie-in, I recommend You consider and acquire or make a Supurcell Prusik Tie-In. It works like magic, but consists of only cord and a simple metal plate with 2 holes — nothing critical, and easy to make at home by anyone with basic tools: saw, drill, vise, file, hammer, crescent wrench, etc., or a friend who has these.
Feel free to ask me about this. Orvel
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