by Paolo Bavaresco for "Landscaper"
Probably the most important component of
a climbing system is the lowly friction
hitch. It is needed for safety in ascent,
work positioning and descending. It is cheap
to replace and as of yet has no mechanical
equal. It is often surprising to many that
tying the same piece of line in a slightly
different configuration can have such an
effect on hitch performance! The aim of
this article is to enlighten those that
feel their ‘Prusik’ hitch offers
the same performance as a ‘Machard
Tresse’ (French Prusik).
"In the beginning, God created Herr
Prusik, and Herr Prusik created a hitch
that Arborists would use".
And so it is written in the Tree Climbers
Bible. However, the Prusik hitch has disadvantages
and innovative climbers have succeeded in
overcoming them. It is difficult to credit
any one individual as the inventor of a
knot as like minds invent alike, name their
invention differently and then argue about
who thought of it first. The names given
to hitches in this article are the ones
commonly come by.
Before delving into the specific performance
of each hitch, the basic physics of climbing
systems must be understood:-
- Imagine a lifeline passed over a branch
and connected to a climber’s saddle
with a bowline and friction hitch (as
in the body thrust technique). The climber’s
weight is supported by both the hitch
and the bowline, meaning the
friction hitch only has a force of half
the climber’s weight acting upon
it. This is likely to be
reduced by the friction of the branch
holding some of the weight. Using a friction
saver will put more wear on the friction
- If the same rope is now passed over
the branch and the friction hitch is tied
around both legs of the rope, the climber
hangs only on the friction hitch (as in
the footlock or single rope technique).
All of the climber’s
weight is applied to the friction hitch.
Depending upon the type of hitch used,
this climbing situation may require one
or two extra wraps to be taken to hold
the additional weight. Some hitches, when
tied as an ‘open system’,
should never be used in this situation.
No friction hitch should be used as a
sole means of descent if all of the climber’s
weight hangs from it.
Open & Closed Systems
Some friction hitches can be tied open
or closed, which affects performance. For
example, a Prusik can be tied with a single
length of rope and secured with a figure
of eight stopper knot. This is an open system.
It can also be tied into a loop or both
legs tied onto a karabiner. These are closed
Types and Diameter of Prusik
The mountaineering rule of thumb is that
whatever line is being climbed, a Prusik
cord half the diameter is required for a
positive grip. However, this rule is for
climbing a single rope and only applies
in arboriculture to the footlock and single
rope technique. When using a friction hitch
in the body thrust technique, only half
the climber’s weight needs to be held,
as already established. This enables a hitch
to be effective using a cord of the same
diameter as the climbing line. The American
ANSI standards require a minimum hitch cord
diameter of 12mm. This prevents the use
of many of the better performing hitches
that I shall mention later. However, FASTCo
401 recommends a minimum rope diameter of
10mm. Most of the hitches photographed for
this article were all tied with a 130cm
length of 10mm double braid and secured
with a double fisherman’s knot. Friction
heat wouldn’t be a problem in the
footlock, so kernmantel rope can be used
(not as hard wearing as braid). Smaller
diameter braids suffer more from friction
heat than larger diameters. This is not
the case on an adjustable lanyard. With
some hitches, this heat can be felt through
the hand. Dynamic Kernmantle cords may offer
better performance than static braids but
typically don’t wear well.
This is the traditional hitch used by
British climbers and popularised by Merrist
Wood College by using a two-ended rope technique
with Prusik loops. These loops aid hitch
performance and safety. Loops also prevent
the hitch from loosening too much when left
hanging between changeovers. The Prusik
grips somewhat better on 3-ply than it does
with braided arborist rope. However, this
can be remedied with 10mm diameter braids
and by tying a 6-wrap Prusik instead of
4. Can be loaded from either direction.
Prusik lock hampers slack tending with the
fair-lead pulley. Can be used for the footlock
with 6 wraps.
The Prusik Soube or Schwerbisch
Similar in performance to a Blake’s
hitch but tied as a closed system. Doesn’t
tend to lock up like the Prusik and can
be loosened easily. Cannot be tied with
a loop. Will only grip in one direction.
Similar in performance to the Prusik Soube.
Normally tied with a loop. Will only grip
in one direction. Can be used for the footlock
with 6 wraps.
Tends to roll when tied open. Tends to
grip tightly but more difficult to loosen
than a Prusik, hence poor fair-lead pulley
performance when slack tending. Must not
be used as an open system for securing the
footlock. Cannot be tied with a loop but
can be tied into a loop, or both ends can
be secured, as in the photo, for a closed
Blake’s or Polish
Works well with 12mm braid, hence popular
in America. Can be adjusted to any length
for long body thrusts or branch walking.
Grips without jamming and free slides with
a fair-lead pulley. Cannot be tied in a
loop or as a closed system. Will not roll
out like a tautline but should be secured
with a stopper knot. Works well with the
footlock but should be tied with 5 or 6
wraps instead of 4. Will only grip in one
Tends not to jam or slip. Can be tied long
or short. Must be tied in a closed system.
Very responsive. Will grip equally well
on a single line system. Will only grip
in one direction. Free slides with fair-lead
pulley for slack tending and grips positively.
Can be tied with any length of cord.
The Machard Tresse (loop) /
Valdotain Tresse (cord with eye each end)
or French Prusik
Must be tied in a closed system. Can be
tied with a loop. Never jams. Very free
sliding – it’s either on or
off! Doesn’t always grip instantly
if tied to long or with too thick a cord.
Never jams even in wet conditions. Will
only grip in one direction.
The Bachman or karabiner jamming
Must be tied as a closed system. Must incorporate
a locking karabiner. Normally tied with
a loop. Good performance on wet ropes. Can
be used with a fair-lead pulley. Will only
grip in one direction.
One method of body thrusting using these
short hitches is to pull hand over hand
above the knot, and then hold with one hand
whilst pulling under the fair-lead pulley
with the other to remove slack. Semi-footlocking
automatically slides the hitch up via the
fair-lead pulley. Very easy to set up as
an auto prusik system.
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