Anchors are the most critical component of any rope rescue system.  The entire rescue is in jeopardy if the anchors are not reliable.  Anchor systems are made up of two major elements;

1. Choosing the best anchor (i.e. boulders, vehicles, trees, and bolts), and

2. Rigging the anchor.

Building an anchor system requires much practice and experience. When dealing with structures, chose anchor points which are part of the inherent structure of the building.  This includes columns, beams, anchors for window cleaning equipment, and elevator housings. Avoid corroded metal, weathered stonework, and deteriorated mortar.  Avoid using vents, flashing, gutters, and chimneys.

When using a vehicle for an anchor, remove the ignition key, set the brake and chock the wheels.  Do not use the bumper.  Connect directly to the vehicle frame using such items as the axle, cross member or tow hooks.

Often a desirable anchor is off to the side of a needed direction of pull.  Ideally, they should be directly above and close to the fall line.  When this is not possible (which seems to be more times than not) advanced anchor rigging skills come into play, namely, focusing the direction of the main anchor to a viable position.

Wrap 3, Pull 2 

Based on the diameter of the anchor, select an appropriate length of webbing, wrap the webbing around the anchor 3 times, and tie an overhand follow through bend with it's ends.  Dress the wraps in a way that will position the bend on the first wrap and next to the anchor, pull the remaining two wraps and attach a steel carabiner (with the gate pointing down hill from the anchor).  Attach the next link of the system to this carabiner, i.e. anchor plate, figure 8 on a bight, systems rack or tandem prusik belay. 

Rope may be used in place of webbing when wrapping very large anchors, i.e. a boulder ten feet in diameter.

High Strength Tie-off
A high strength tie-off is used when maximum strength of the rope is needed, i.e. highline operations.  

The “high strength tie-off” is made by wrapping the line enough times around a “bombproof” anchor to take the tension off the knot on the last wrap.  The smaller the diameter of the anchor the more wraps of the rope is needed.    

Tie a "figure 8 on a bight" or a “bowline” on the working end of the rope, and connect this knot to the standing rope just in front of the first wrap by using a steel carabiner.  It is also acceptable to simply tie the tail of the last wrap around the standing part of the rope.  

As a rule of thumb for a high strength tie-off, avoid using anchors that are less than 3 inches in diameter.    

Self Equalizing (Load Distributing)

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Fixed Multi-point (Load Sharing)    
Like a self equalizing system, load sharing is used to combine multiple marginal anchors to one focused point.  In addition, load sharing is also useful in taking two solid anchors to focus a more desirable location for the fall line.

Back-ties  
Sometime a questionable anchor, that has a preferable location to the fall line, can be used by anchoring that questionable anchor to a bombproof anchor.  This is done by back-ties, typically using the wrap 3, pull 2 technique on both anchors, then connecting the two anchors by using a 3:1cd MA.  All 3 legs of the MA should extend the full distance between the front anchor and the back anchor.  By using this full length MA, rope stretch in the “back-tie” will be kept to a minimum.