Prusik take a bow ?
Is it time for the humble Prusik to move aside ? Maybe not but
after the recent climbing competition I think the issue needs to be addressed.
The knot itself takes its name from the guy who invented it - Dr Karl Prusik.It can be made from any thickness of rope as long as it's basically of a lesser diam. than the main rope. The two ends are tied together to form a loop by means of a
"Double Fisherman's Knot". This is then wrapped 2 to 3 times around the rope, more wraps = more friction. Being a friction knot it relies on the two surfaces/textures of the ropes coming together to bind. As with most friction devices it generates heat.
After seeing 2 Prusik loops almost fail at the recent climbing competition due to excessive heat build up as the climbers completed their controlled decent, I thought it might be time for a wake - up call.
The Prusik was designed as a means of being able to "tie off" mid pitch or as a soft alternative to a mechanical device ( Jumar, Gibbs, SRT, Shunt) as an ascender.
There is no reason not to use the same knot to descend as long as it is controlled.
As mentioned earlier friction produces heat build up. A static rope ( Prusik) passing down a running rope(main Line) generating friction can cause our Prusik to burn through with excessive speed.
Two 6mm Prusik cords had to be thrown away after the climbers had untied due to the inner core of the cordage being exposed. These were brand new. The outside sheath was totally burnt through and the white fibres inside had started to burn. Clearly this was not a controlled descent.
They only used 6mm prusik cord I hear you say. That is the case but how many times do climbers check or change their Prusik cords, even if they are 9mm or part of the main line. Personally when I use a Prusik I prefer a smaller diam. Prusik 6 or 7mm as I find it binds better and doesn't travel which sometimes can happen if not loaded properly.
Alternatives which are suitable and are not prone to heat build up on the rope are the mechanical type. I have used a "Petzl Expedition" handle type ascender for a while now and wouldn't switch back. Initially they are more expensive and it takes a few goes to master the use but they make for a more easier climb and you don't experience heat build-up when descending.
This is by no means an article to bag the Prusik I think it is a great knot - used properly.
Clearly the Prusik still has its place but should not be taken for granted.
Dave Crispin.
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