The
Anchor: Look before you Leap.
All too often in descending accidents, failure of
the rappel anchor is
the main cause. Remember, just because someone else
previously used a
given anchor is not an adequate reason for you to use the same
anchor.
Pitons loosen, rock fractures, slings become
frayed or a
given anchor may have been woefully inadequate to
start and someone
before you was lucky- and you don't want to count on luck too often.
When many of us started climbing in the early 80’s (and
before- and
since?), there was a strong ethic in the climbing community that
discouraged leaving gear behind and that only the
absolute minimum
equipment should be sacrificed in a descent.
It seemed strange to me
then and now, that a person who would take great caution to set-up
solid anchor systems on their ascent would risk it all on a sketchy
rappel anchor (rappelling off of one nut or a loose block) just to save
a few bucks.
The same rules that apply to climbing
anchors should apply to rappel anchors: Solid,
Equalized, and Redundant.
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Click on photos to enlarge.
An
example of a 3-piece equalized rappel anchor that is redundant
down to
this Omega Pacific aluminum ring which is rated to 20kn (1 or 2 kn weaker than
your
rappelling carabiner). All knots are an overhand
follow-through.
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Solid:
Un-questionable
strength
Rappel
anchors need to hold significantly more than body weight.
Each point of
an anchor, be it one large tree or three pieces of gear needs to be
individually solid. Check each component thoroughly:
Is the tree
alive?
Does it move when you shake it?
(bad sign)
Are the wires
connected to the nut?
Are the pitons
super rusty?
The worst decision
you can make while rappelling is to have blind faith in the
anchor.
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A
single-rated 9.3mm rope and a 7mm cord are tied together for a
light-weight alpine rappel system (both are 60m long). The
knot is a
flat overhand which binds well on the different diameter materials and
there is another overhand with the cord around the rope.
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Fixed Gear- To Trust it or Not?
Be
wary of fixed gear - test it before you trust your life
to it.
I’ve
pulled out dozens of pitons with a firm outward yank and removed
countless old bolts with little more than a few tugs.
Pitons
and old
bolts rust with age and the freeze/thaw cycle which takes place in many
environments can cause pitons to easily pull-out, sometimes in less
than a few days after being placed.
When in doubt, add more gear
(nuts
or hexes are cheapest). Hitting pitons with a rock
can give you an
idea if they are solid or potentially you can knock
it back in with the
stone hammer.
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The
overhand follow-through is the easiest knot to connect cord or webbing
to nuts, pins or bolts. Once you've figured out where you
want the
knot, simply tie the first overhand, loop the tail through your anchor
and retrace.
Hint- pull in a few inches of slack when
tying these
knots so that when they tighten the length provides an equal load to
all anchor points.
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Equalized:
Share the load
equally
Be
warned: the "American Death Triangle" (ADT) is not an anchor that
shares the load equally among all of it's
components.
The
self-equalizing (magic-x) method is best at equalizing the load, but
suffers the fatal flaw of serious shock-loading
potential should one
piece of the system fail.
Pre-equalized
(all points connecting to one
master point via knots) and shown at right, is the most
fail-safe anchor method available
as it is relatively equalized without the shock-loading
risks.
I
don't believe that anyone has actually died from the ADT as
they are often tied between very solid bolts.
I do know that many climbers have
died because their rappel anchor was not adequate for the load.
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An
overhand follow-through on both sides of the red cord connect it and
equalize it with the rest of the anchor system.
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Redundant: Don't depend on just one.
Multiple
pieces of solid gear are the way to go, with each piece
holding it’s equal share of the weight.
The
only time I rappel from one
point is when it is a healthy living tree that is bigger than my fat
uncle's thigh.
Connecting
the same pieces of gear together with less material (one 3' sling)
using a method of tying knots to create redundancy
down to the metal
link where the rope runs through the anchor.
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The
top piece will have a couple of half-hitches connecting it to the
sling- like all knots and hitches it is important that they
are
completely tightened before use.
All of the other knots
are either
overhand on a bight or overhand follow-
through. Essentially the same
knot (an overhand on a bight) tied differently.
This aluminum carabiner used for
a rope connection at right is 23kn strong. The aluminum link shown
above is rated to
20kn and a steel link (3/8") have been tested to 30kn. All
are sufficiently strong for
rappelling.
The carabiner has been taped shut so that it
cannot come "unlocked" or pushed open against a rock surface.
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The
Master Point: Your connection to this world.
The master point is what any anchor comes down to:
make sure you are
using the right materials and applying the same principles of Solid,
Equalized and Redundant.
Metal links at the master point are always a
better idea than relying on the nylon from cord or webbing.
I have seen ropes of the same diameter burn through
one inch webbing
because they move through a rappel device at different rates.
Aluminum
rappel rings are the cheapest solution but remember that these are
hollow and
unless brand new should be doubled up to assure adequate
strength.
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Steel links bought from a hardware store
or climbing shop (5/16”
minimum) are the more modern solution for long-term anchors and their
stamped strength is actually 1/3 of their full strength as they are
manufactured for industrial use which has different rating guidelines -
the strength should be printed on the side of the link.
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