Ventura County Search & Rescue, Fillmore Mountain Rescue Team 1
 
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ANCHORS


OVERVIEW

A fundamental aspect of all technical rescues and evacuations is that at some point the system must be attached to a rigid object. This attachment defines an "Anchor."  Selecting anchor sites and constructing anchor systems is the object of this section. Climbing, Rappelling, and general rescue have similar requirements for anchors. Placing anchors is an art based on physical and mechanical properties of nature which must be practiced frequently to gain confidence and expertise.  

DEFINITIONS  

Directional Anchor is an anchor which is useful in a limited direction only. This implies that the anchor will not work or will fail if force is applied in a direction other than the direction for which the anchor was designed to operate.  

Omni-Directional Anchor (Sometimes referred to as a "Belay Anchor") is an anchor which is designed not to fail regardless of the direction of pull. This type of anchor is required as the first and last anchors in a leader climb. As is shown in figure -1 the anchor will operate if the force is exerted upward, downward, to either side, or any combination of the above.  

Natural Anchor is an anchor created by attaching webbing or rope directly to an object that is found in nature, such as a tree, a large boulder, a clump of grass.  

Mechanical Anchor defines all other anchors that are not pure natural anchors. A hybrid anchor may exist where part of an anchor system is attached to a natural item while the other may be connected to a truck. Climbing nuts, trucks, and driven stakes are some examples of mechanical anchors.  

Bombproof is a descriptive term applied to an anchor to indicate that the anchor is highly stable. The anchor will hold even under the worst imaginable load. The anchor would at least be 10 times stronger than that which is required. This would include:  Girth Hitches around large trees, chocked vehicles, and giant boulders.  

Sturdy is a descriptive term applied to an anchor to indicate that the anchor is very stable and has a sufficient margin of safety for the specific application. This term would be applicable to most driven stakes, large passive climbing pro, well placed snow anchors, or large brush.  

Limited is a descriptive term applied to an anchor to indicate that the anchor has adequate strength for the required application but the margin of safety for loads above the expected load is not present. This type of anchor will normally be used in combination with other anchors to operate as a single system anchor. Limited anchors would include well placed climbing pro, climbing bolts, and most snow anchors.  

Weak Anchors are anchors which will not be able to hold the required worst case load. This type is almost always used in combination with other anchors to create one sturdier anchor. Climbing protection placed in sandstone, climbing pro with poor directional insertion, grass clump anchors, and all body weight anchors are considered weak anchors.  

Urban Anchors are any anchors created from buildings, structures, or other non-alpine settings. These are used for earthquake scenarios where it may be necessary to evacuate people from buildings.  

Body Weight Anchors are usually hasty anchors generated by people either sitting or lying on the ground. The rope or webbing is then attached directly to the people as if they were rock anchors. This is useful as a hasty anchor in urban applications and low angle work in the snow when other more appropriate anchors are not available or would take to long to create.

Combined Anchors are any group of individual anchors that are grouped together to operate as a single anchor with respect to an operation. i.e.  Three climbing nuts may be connected to form a single anchor for a sturdy belay system.  

Self Equalizing Anchors (SEA's) are combinational anchors which are designed specifically to distribute the total system load to a number of individual anchors. The resultant load on each of the individual anchor attachment points will be the same as the other attachment points.  

Redundant Anchors are combinational anchors attached in parallel with at least one other anchor. In this case the load is normally held by one of the anchors. In the event of a failure of the primary anchor, the secondary anchors are available to accept the load.   

Anchor Rope is a small section of rope normally used to attach to anchors or to form a single SEA. The length is arbitrary but is usually less than 50 ft.  

Runner is a section of tubular webbing (typically 1 " but 1/2 tubular is utilized) tied or sewn in a continuous loop. An overhand follow through is used to tie the two ends together. A short runner is normally created from 5 ft of webbing and a long runner is created from 15 - 20 ft of webbing. See figure - 2. Rope sections that are used as anchor ropes should be tied in a continuous loop using a double fisherman's knot. - 2. Rope sections that are used as anchor ropes should be tied in a continuous loop using a double fisherman's knot. - 2. Rope sections that are used as anchor ropes should be tied in a continuous loop using a double fisherman's knot.  

DETERMINATION OF ANCHOR REQUIREMENTS  

Prior to selecting the type of equipment necessary to build an anchor, the anchor requirements must be defined. On a rescue, the operations leader must define the requirements to the person assigned to construct the anchors. Since much of an operation is executed simultaneously with other aspects of an operation, it is imperative that anchors be constructed reliably, in accordance with team standards, and quickly. Since limited time and assets are often major constraints, the optimum anchor is not always achievable. It is important that the rescue member be able to assess an anchor with respect to the adequacy of completing the required task. For example, a simple webbing girth hitch may be adequate for an anchor to lower a rescuer to a fallen subject, but would possibly be inadequate for a tyrolean across a river. Important criteria to consider when creating an anchor are:  

            Required strength of the anchor (Continuous Load)

            Required shock load capability of the anchor

            Direction of pull (force)

            Possibility in change of pull direction

            Length of time the anchor will be required

            Physical location of the anchor

            Quantity of gear available for this anchor

            Required Redundancy (or reliability)

            Time when the anchor is required  

The required strength of an anchor is a judgment call. Ideally one would prefer to have an anchor capable of handling 300 percent of the worst case load. During technical evacuations one should consider the minimum rescue load to contain 2 rescuers and the subject plus gear which would be approximately 600 lbs. For shock loading the anchor should be able to withstand 1200 to 1800 lbs (2 to 3 times the minimum weight) of force.  

Some guidelines for anchor selections are given below:  

Some Typical Anchors  Static Load  
Groups of weeds
(i.e., poison oak)          
60 lbs.  
Small brush  100-175 lbs.  

ONLY AT BOTTOM 
NEAR G
ROUND
Large snow-brush etc.   

 100-225 lbs.
Sturdy thick multiple brush 150-275 lbs.  
Small climbing nut 
(local use)
100-200 lbs.
Large nut (local use)  200-450 lbs.  
Granite placed 
Climbing Pro
300-700 lbs  
Girth hitch tree/vehicle  600-900 lbs.  
Webbing around rock 800-1200 lbs.  

In each case the anchor should be tested if possible. Having several people pull against the anchor is a simple effective test. The strength of the anchor depends on the webbing or rope strength as well as the attachment point stability. One inch webbing or 8 mm line are normally rated at or above 4000 lbs. It is best to design the anchor so the force is applied over the greatest amount of surface area. If the anchor point is a rock, it is best to choose a large one with rounded edges rather than a skinny rock as is depicted in figure - 3.

The direction in which the anchor must operate is as important as the strength the anchor must possess. Figure - 4 indicates a directional anchor that will definitely fail in one direction, while being completely safe in the other direction. The omni-directional anchor is required for initial anchors for leader climbing since the direction of the arrest force is typically out and away from the wall being climbed. Alternate or combinational anchors should be utilized if the force can come from several directions. - 4 indicates a directional anchor that will definitely fail in one direction, while being completely safe in the other direction. The omni-directional anchor is required for initial anchors for leader climbing since the direction of the arrest force is typically out and away from the wall being climbed. Alternate or combinational anchors should be utilized if the force can come from several directions.  

Figure - 5 uses two climbing nuts placed in opposite directions to account for an upward and a downward pull. When not in use, the separation of the two nuts keep the other climbing nut from working out of place.  

If an anchor is required to operate over an extended period, such as might be required when a tyrolean is used to evacuate a community during a flood, anchors that do not work themselves loose with vibration and are able to withstand long term stretch are required. If possible each anchor should be checked periodically or prior to each loading of the anchor. A visual inspection is often sufficient. In long term anchor applications, one should concern himself with any abrasion or stress points that the anchor may have created. Shock absorbing devices such as mariners knots or expansion straps should be used in line with the anchors to reduce the effects of shock loads on the anchor.  

What sounds overly simplistic is the location of the anchor. Many times an anchor is not available where it is most needed. Use of extra rope or runners as is shown in figure - 6 is one method of placing an anchor where it is needed. For systems work on a plateau, anchors are best placed deep (away from the edge) and high to keep raising system equipment out of the dirt. High anchors also place the system gear at a comfortable working level for the rescuers. 

However, sturdy anchors are not often available at comfortable height. Less stable brush is strongest at the bottom near the ground. If this weaker type of anchor is utilized then it is necessary to place the anchor attachment point as low as possible which will force the system gear to operate at ground level. Figure - 7 is an example of an anchor placed "deep and high" for use in a raising system.  

 In any given operation, anchors are utilized in groups. For example a single station of a multi-station evacuation may require a raising anchor, a belay anchor, a rappel line anchor, a rappel belay anchor, and a tag line (safety) anchor. If each anchor were wasteful in the amount of gear that it utilized, a tremendous amount of gear would be fielded to execute the operation. The team assigned to create anchors should be able to judge (calculate) the amount of gear necessary to complete the task. In general, it is best to be frugal with the anchor gear. (Must have the same reliability though.)  It is surprising to see how fast 25 biners are used in a technical evacuation. In long evacuations, it may be necessary to break down a given station after it has been utilized so the gear can be used at an upcoming station. This "leapfrog" of gear requires that the anchor team have a good idea of what gear is being utilized at each station so the placement time can be minimized.  

Another consideration that the anchor team should note is the time at which the anchor station is required. Having anchors pre-established at a site will assist in expediting an evacuation, which may provide vital time that the subject requires to stay alive.   

ANCHOR PREPARATION

 When assigned to prepare an anchor site, be sure to understand what is required. When assigned the task, it is best to repeat the task to the leader to verify the assignment. If the task is complicated such as many anchors at various sites, it would be prudent to write down the assignment in a pocket notepad. If help is available use the help wisely. Separate the task into smaller tasks and work in parallel. When complete with the assignment, advise the leader but stay in the anchor area until a new assignment is given. Once a plan is instituted, stay with the plan unless a major problem surfaces. Avoid entering a mode where the anchor is always being "made better."  

Clean and orderly anchor stations allow for easier verification and checking, easier modification if required, and easier tear down when completed. A neat and orderly system helps in every aspect of an operation, but anchors can easily become confusing. If several anchors in a given site are to be created, a central equipment cache should be located where gear not in use can be stored. While constructing an anchor, the rescue member should wear the systems equipment rack over the shoulder or place the rack in a safe location (preferably hanging if possible). Avoid placing gear on the ground. Loose gear can be kicked over the side which presents a hazard for the rescue team working below and eliminates that piece gear from availability. Gear easily becomes lost in snow during winter operations. A spare attachment point created from an additional webbing sling or a middleman's knot as is shown in figure - 8 may be used to hold spare equipment used at a station.  

NOTES ON WEBBING ROPES AND GIRTH HITCHES  

Natural anchors use webbing, rope sections, or actual system ropes to attach directly to solid objects such as rocks, trees, etc. One inch webbing runners are usually the first choice. The flat webbing profile allows a greater surface area and greater friction around an object than does round rope which helps to keep the anchor from moving or turning out of position. The girth hitch is the manner of choice for securing a runner or a continuous loop of rope to an object.

Note the direction that the girth hitch is applied in figure - 9. This manner helps to keep the girth hitch taut which will help to prevent movement of the webbing which could cause wear and a possible failure. Since webbing is made from nylon (or other synthetic material) it is designed to stretch under loads to compensate for shock applications. As webbing becomes older, the elasticity becomes less which makes the webbing more apt to fail under a shock load than a newer section. Sections of questionable age or webbing that has a faded color should be retired from use. In normal team usage runners have a life of 2 to 3 years dependent on use and care. Commercially prepared runners are available at mountaineering shops with the loop ends sewn together. Commercial runners are available in 1/2 and 1 inch widths in various lengths.  

 A rabbit runner may also be used to create anchor attachments from webbing. A rabbit runner is made by tying attachment loops in the two ends of a section of webbing using overhand follow through knots. The length of the webbing section is arbitrary but 36 to 48 inches is typical. Commercially prepared rabbit runners are also available from dealers with sewn loops. The loops are designed to attach to biners. Some uses of the rabbit runner as an anchor are shown in figure -10.  

 SAR Teams utilizes specially constructed "Rescuer Runners" which are built in a fashion similar to rabbit runners but are 6 ft long and are constructed from 2 inch flat (rather than tubular) webbing. The extra width allows the load to be distributed over a larger surface area. A supply of theses runners are kept in the team systems pack.  

Prior to each use of a runner, or loop of anchor rope, the item should be visually inspected for abnormal wear, tearing, or a loose knot. If the knot is loose it should be immediately re-tied. If the item appears suspect due to wear it should not be used. Retire worn webbing to a pocket or backpack to prevent its inadvertent use later in the operation.  

If a situation occurs where the available runners are too long for a given application the runner may be used "doubled up" as is shown in figure -11. In this manner the runner length is halved each time the runner is doubled. Usually the thickness of the webbing will only allow this process to be used one or two times depending on the length.  

Also if a girth hitch is being used, an alternative method for shortening the runner length is to double tie the girth hitch as is shown in figure -12. Especially with pre-tied runners, one should avoid changing runner lengths by untying and re-tying knots.  

Runners may be connected together, to function as extenders. A common mountaineering extension is shown in figure -13.

In this case one runner is directly attached to another using a girth hitch. (This actually forms a square knot.)  The runners should be tightened to prevent any movement. This extension is simple, does not require tying knots, may be implemented when only one hand is available (as when climbing to place an anchor), and does not use any hardware (no biner). This extension may be repeated several times until the proper length is achieved. For this reason many climbers carry only one size runner and use combinations of runners or doubled up runners when needed.

NATURAL ANCHOR POINTS  

In mountain rescue operations, securing to good natural anchors is the preferred method of anchoring. The fact that the anchor is present is an indication that its stability has withstood the test of time. However one cannot be overconfident with just appearance. There have been reports of boulders (weight around 1200 lbs) being dislodged or failing due to the force used during a rescue operation. In some advanced applications such as tyroleans, extreme forces can be generated by the systems in use.  

Large smooth boulders, tree stumps or large brush (manzanita) all provide adequate strength anchors for system operations. Objects may be secured by using a girth hitch or by encircled the object with a rope or webbing section as is shown in figure -14. When using a girth hitch, the knot of the runner should not be placed against the surface of the anchor. The knot of the runner should lie in the system attachment point area away for the end of the biner attachment zone.  

Proper knot placement is shown in figure -15. When using a large boulder one must be certain that the direction of pull will not lift the webbing or rope section over the boulder or through any gap that may exist under the boulder. Check for sharp edges especially in the area where the ground meets the boulder. If sharp edges are present and alternate sturdy anchors are not available, padding should be used to protect the webbing or rope section.  

Large trees that are alive are excellent anchors. Dead trees should be treated as suspect unless testing proves they are safe. The bark of some larger trees can be abrasive to webbing. To prevent undue damage to both the tree and to equipment due to anchor movement, one should use a snug anchor attachment such as a girth hitch rather than an open loop of webbing or rope. Although sap presents no immediate danger to webbing or rope, the drying of penetrated sap will create a hard inflexible section in the anchor material which may create a failure point at a later time. Proper cleaning of rope and webbing helps to prevent the effects of absorbed sap.  

VEHICLE ANCHOR POINTS  

For technical rescue operations within reach of a rescue vehicle, the vehicle itself may be used as an anchor point. As was mentioned earlier, large natural anchors are preferred. Vehicle anchor should be attached to the frame of the vehicle where the strength of the vehicle structure is highest. Fire trucks have large "eye" bolts in the front and rear which are designed to operate as "Hard Points."  The SAR trucks do not have factory prepared hard points for attachment. Padding should be used to protect nylon anchor equipment from sharp edges and engine oils. The longitudinal axis of the vehicle (front to back) should be in line with the direction of pull of the load. Wheel chocks should be used to stabilize the vehicle. The vehicle should not be running. Obviously extreme care must be taken to prevent anyone from inadvertently moving the vehicle. Redundant anchors should be used, preferably with each one on a separate superstructure of the vehicle. Bumpers should not be used as attachment points.  

With fire or forest service trucks, the wheel diameter is large enough to support an anchor by feeding webbing through the holes of the wheel and securing with a girth hitch as is shown in figure -16. Attaching to fire truck wheels is often the anchor of choice for "vehicle over the side" operations.  

DRIVEN STAKES AND DEAD MAN ANCHORS  

The team maintains steel stakes for use in areas where no natural sturdy anchors or vehicle anchors are available. The stakes are 3/4" steel bars that are 3 ft long. The strength of the anchor is dependent on the pack of the soil and the depth of penetration of the stake. The strongest attachment point of a driven stake will be as close to the ground as is possible. Stakes should be driven at a slight angle away from the direction of pull. Multiple stakes may be used together as a combinational anchor called a dead man anchor.  In the dead man anchor the top of each stake is secured to the bottom of the next stake. A single length of rope may be used to combine the stakes (figure -17). Additional tension may be created between the stakes by including a tensioning device (similar to the operation of a tourniquet) between the stakes as is shown in figure -18.  

 The steel stakes are to heavy to be practical for backcountry applications. In addition a sledge hammer must be carried to drive the stakes into the ground. The process of setting stake anchors is time consuming, so therefore advanced notification of anchor placement requirements is needed. However for operations a short distance from vehicle access, urban operations, or when an airship is available to ferry equipment, the driven stakes may be a wise choice to provide the necessary sturdy anchors.  

In addition to driven stake dead man anchors there are also buried dead man anchors. This type of anchor is more applicable to self winching a vehicle from a stuck position than having any application in rescue operations. The principle is to bury an object that is large enough under enough ground pack to support the weight of the load. For example, using a railroad tie on the side of a hill to winch out a vehicle. This principle is used to create anchors in snow packed hillsides with remarkable success. Since this type of anchor construction will obviously require time and digging equipment, it is probably the last choice in the list of anchors.

CLIMBING PROTECTION  

Much of alpine rescue operations will place rescuers on vertical walls or rock faces where oversize boulders and large trees are not abundant. Often the most expedient or only route to an injured subject may be to climb a technical wall. Even if the top of a face is available, the stuck subject may be several pitches below the top which will require several operational stations to be placed on the wall.  

The team maintains an adequate stock of mountaineering / rock climbing anchors for use on operations. This equipment is normally kept in the assault pack. Intrusive anchors such as pitons (which are rarely ever used by anyone) or bolts, are artificially placed in the rock by wedging, driving or drilling into the rock face. Non-intrusive anchors such as friends, nuts, chocks, bongs, hex's etc. make use of existing cracks and fissures as attachment points. In addition to not marring the rock face, non-intrusive anchors again make use of natural attachment sites which have withstood the test of time which is some indication of the stability of the attachment site. The team no longer maintains any pitons but a small bolt kit with a hammer drill is included in the assault pack. A battery powered Makita hammer drill is also kept in the utility truck. The battery will last approximately 1 hour of hard drilling. A selection of different size protection elements is necessary to accommodate the wide variance of wall cracks and attachment areas.  

Climbing protection derives its name from commercial names created by the device manufacturers. Chocks and nuts are basically synonymous. A size scale is applicable to these with the size following a manufacturer's specification and not any specific standard. The smaller anchors are for smaller cracks. Simple Chocks or nuts are available in pre-wired nuts or in individual elements that require anchor cord attachments. Older anchors typically used a lower stretch high strength Perlon rope (6 to 9 mm) for anchor cord. This would provide a breaking strength of 3000 to 4500 lbs.  

More modern rope comprised of Kevlar, Spartan, or other high strength cord is available for use. The newer cord has strengths in excess of 6000 lbs for 5mm Kevlar. The newer cord cannot be cut and melted as standard nylon cord. A special procedure to cut the inner core and to melt the outer sleeve is required.

    Anchor cord distributors will normally offer this service when the cord is purchased. Also the cord is not as flexible as normal climbing line which allows it to be useful in small sections only. Anchor cord is attached to the anchor and kept together permanently as a single unit. Each individual anchor is usually kept no longer than 15 inches. This keeps anchor pieces from interfering with climbing when they are attached to a shoulder sling.  

All anchor cord should be attached using a double fisherman's knot as is shown in figure -19.  

Figure -20 contains a diagram of chocks and some of their placements. To be useful, a decreasing width or parallel wall crack must exist. Start from the direction away from the direction of pull, insert, and pull the anchor until the width of the crack is spanned by the width of the chalk. It is best to have as much surface area of the chock in contact with the wall as is possible. In this manner, the load that is placed on the anchor will be distributed along the contact area of the anchor.  

If only a small section of the chock is in contact with the wall as is shown in figure -21, an unstable anchor will result and the anchor may fail when the anchor is loaded suddenly.  

Small wired stoppers that use 1/16 inch cable are rated at approximately 700 lbs by the manufacturer (Black Diamond Stopper Nuts). Number 6 stoppers which are approximately 1/2 inch cubes and higher size nuts are rated at approximately 2300 lbs. When using wired nuts or Kevlar line, the user should place a shock absorbing material between the wired nut and the system load if shock loads are expected. The wire cable and the Kevlar do not expand as efficiently as does nylon cord.

Hexcentrics are a special type of climbing protection created from hollow or solid 6 sided aluminum extrusions. The hexcentric is designed to operate in either position shown in figure- 22. The non-symmetrical 6 sides of the protection accommodate cracks that do not have parallel walls better than a standard stopper chock. Hex's come in small wired sizes and larger sizes which require anchor cord attachment.   

Bongs are large anchors created from tubular sections of aluminum. These are light and practical for local sandstone operations. Tubular Expansion Anchors are available from vendors. The expanders are designed to adjust in length when the barrel of the anchor is twisted. This adjustment allows one bong to fit many different size cracks.  

Friends (Patagonia Product name) or in general terms, the Positive Force Camming Anchors, is modern technology at work in the alpine situation. These devices are designed to have expanding cams which may be retracted through the use of a simple trigger mechanism, inserted into a crack, and expanded to create a simple sturdy anchor. The cams hold the element in place under limited or no load but are capable of withstanding loads in excess of 3000 lbs in the direction of pull. Some active camming devices are shown in figure - 23. Practice is needed in the application and safe use of the camming anchors prior to their use in actual operations. The friends can be placed with one hand in a difficult crack with relative ease which make these devices extremely attractive for leader climbing.

 Some friends, especially those with a solid shafts are highly directional anchors. Off axis forces may twist the cam and release the anchor unintentionally. The solid shafts have been replaced by flexible shafts on the more modern ones to reduce the effect of off axis forces. The cams should never be fully retracted prior to insertion into a crack. Some retraction is required to release the anchor during removal. If the camming anchor is locked into the crack with full retraction, it may be impossible or at least difficult to remove the anchor after it has been loaded. The cams must be so placed that some part (ideally best to equally load each cam) of each cam is placed in contact with the wall surface. One should always test the placement by tugging the friend in several directions. If the cam is off balance the device may "walk" (move slightly with each tug) out of the crack and fail. Camming devices work best in highly stable rock as opposed to local sandstone which can be broken apart under the force of the loaded cams.  

IMPROVISED BODY WEIGHT ANCHORS

 Occasionally it is necessary to provide a weak hasty anchor for a hasty rappel, a tricky ice crossing, or a hasty evacuation from a burning building. It is possible to use body weight of people and the friction between the people and the ground in either a sitting or lying position as anchors. One must consider these anchors to be weak and useful by themselves only for limited loads. Body weight anchors are best used in combinational anchors. Figure -24 shows two applications of body weight anchors.  

SELF EQUALIZING ANCHORS  

The idea behind Self Equalizing Anchors, SEA's, is to make use of a combination of individual anchor attachment points, such that each individual anchor has the same load as each other anchor attachment point in the system. The load on any attachment point is a "small" fraction of the total load on the complete anchor system. Self Equalizing Anchors provide for reduced loads on individual anchor attachment points and flexibility in the location of the system anchor and the anchor's direction. However SEAs require additional hardware compared to a simple bombproof anchor. SEA's are often required to provide anchors with sufficient integrity to meet the demands of a technical rescue in the alpine environment.

Therefore, in order to optimize the usefulness of the anchor, one should select attachment points and use enough rope (webbing) such that the angle A is forced to be less than 70 degrees. See the examples in figure -26. It is not important to be able to derive the exact mathematical load on any system. It is important to understand the relationship between SEA dimensions and the anchor loads. Three types of SEA's are presented in this section. The three SEA's are noted as:

          . The webbing type - (Typically 15-25' sections)  
            (Best in small areas)  

          . The standard team SEA (bowline and anchors) -
            Constructed from rope - Best for large area's  

          . The bowline on a bight SEA
            Revisionary (not enough equipment)

 

 

Each application of SEAs must be assessed in the field. Real life problems such as attachment points, amount of available working space, and system constraints indicating where the anchor must lie, complicate the anchor system. In judging attachment point strength, only experience (and sometimes luck) can indicate the value of an anchor.  

All SEAs are designed not to fail completely if some, but not all of the attachment points fail. Remember, if one attachment point fails, the anchor's system attachment point will lower and possibly move laterally and in depth causing a jolt. The larger the fall, the larger is the force applied (momentarily) to each anchor. For this reason it is prudent and wise to always release loads slowly and keep all slack out of belay lines. Anchors are more apt to fail under sudden jolt conditions than under steady tension.  

Using standard webbing and dynamic shock absorbing rope one can expect a dynamic load capability of 3 to 5 times the static load capability of anchors. (Higher gains on the sturdier anchors.)  Repeated capture of dynamic loads weakens virtually every part of the anchor system. One should always attempt to avoid dynamic loads.  

THE "WEBBING TYPE" SEA  

The webbing type SEA is used when several anchor points are nearby and a SEA is justified. Given the nearby anchor points (shown as climbing protection in figure -27) a 20 ft webbing runner is first tied using a overhand followthrough knot to create a continuous webbing loop. If a larger loop is needed, multiple sections can be combined to form a single runner. The loop itself shall then be attached to each anchor point. A locking biner should be placed around both sides of the webbing material in the area between each anchor attachment point. Note as is shown in figure -27, the webbing knot should lie in one of the SEA legs away from any of the biners to reduce the anchor friction. There will be one less equalizing biners than there are anchor attachment points. An extra biner is clipped into the webbing loop (note: this clips into the loop, not over both sides of the webbing) to act as a safety biner in the event that only one of the selected anchor points holds. (Although frequently noted, anchor failure should be very unlikely!)  All the equalizing biners and the safety biner are then connected together through the use of another biner. This biner becomes the anchor attachment point for the rescue systems being used. The major advantage of this SEA is the ease of assembly and its ability to be used in small areas. This is very helpful when the anchor attachment points are on a vertical wall.  

THE "STANDARD" TYPE SEA  

The team standard SEA is designed to be constructed of rope and therefore lends itself well to large load requirements but typically requires a larger construction area due to the turning radius of the rope. The standard SEA is shown in figure -28. Some important points to check when creating this anchor are:  To tie the bowline in the correct direction to allow the tail to feed into the center of the bowline. The inner loop can be a bowline or a figure 8 (on a bight) but it must be small and close to the outer loop bowline knot. The general rules of maintaining a major angle of less than 70 degrees applies.  

A good construction technique that allows proper placement of the bowline and the system attachment point is as follows:  

  1. Visualize where the system attachment point needs to be based on the given rescue requirements. This is based on the overall system requirements. If the complete rescue is being controlled from a single platform, then the total area cannot be used to create a single system anchor. See figure -29a.
     

  2. Locate and insert the individual anchors. (i.e. place climbing nuts, attach girth hitches, whatever)  One must estimate the worst case load to be expected. The combined strength of the multiple anchors must be greater than the expected worst case load if the system is to function properly. Locking biners should accompany each individual anchor.

  1. Tie a small figure 8 on a bight at the of the rope.
     

  2. Prepare (N-1) biners for equalization biners.  
     

  3. Attach the rope to all the individual anchors and verify that all biners are now locked. See figure -29b.  
     

  4. Pull the end of the rope (the one with the figure 8 already tied) to the point where the system attachment point should be. (i.e. Point located in step 1. See figure -29c).  
     

  5. Attach an equalization biner on the rope in the area between the anchors starting with the anchor closest to the figure 8. Holding the figure 8 and any previous equalization biners in place, pull each equalization biner (and the anchor rope) to the attachment point location as is shown in figure -29d.  
     

  6.   Repeat step 7 for the (N-1) equalization biners.  
     

  7. After all the leg lengths have been set for the proper positioning of the system attachment point, tie the bowline keeping the figure 8 on a bight in place (figure 8 on a bight is already tied). Attach the equalization biners from step 8) to the (now inner) figure 8 and the anchor system is ready to go.  

  1. This places the system anchor attachment point where it is needed the first time utilizing no guess work. The running end of the rope may be tied off using another larger figure 8 on a bight to provide the anchor attachment point. If enough rope remains in the running end, the opposite end of the rope used to create the anchor may be used as a system line. Use caution to verify that the remaining rope length is sufficient for the required task.  

THE "BOWLINE ON A BIGHT" SEA ANCHOR  

This is an SEA anchor that should be used in a revisionary mode of operation only. This is a stable, sturdy, and safe anchor but does not lend itself easily to be finely adjusted during assembly. The anchor is simple to construct and is a benefit when the rescue is becoming short on ropes and other equipment as would be the case in a multiple station rescue or an unanticipated rescue. Be aware that all revisionary modes cannot be predicted and therefore one should have an understanding of the system so that the principle may be applied to the given situation.  

  1.  As is available place the individual anchors. These should be as close together as possible to conserve on the amount of rope being used in the anchor.
     

  2. In the middle of the rope (This will allow one to utilize both ends of the rope if required for the rescue) tie a bowline on a bight with one loop 2 to 3 times larger as is required to attach all the individual anchor attachment points, and the other loop approximately the size of a clenched fist.
     

  3. Clip the larger loop into all the individual anchors and again verify that the biners are locked.  
     

  4. Clip each of the SEA legs into the smaller loop biners.
     

  5. Tie a figure 8 or a middleman's Knot into the running end of the rope. This should be used as the system attachment point. See figure -30. Note: this is only one system anchor......use good judgment)  

                                                      

  
Ventura County Sheriff's Volunteer Search & Rescue  |  Fillmore Mountain Rescue  |  Team 1
Mailing Address:  P.O. Box 296 |  Fillmore, CA  93016
 
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2005 Ventura County Sheriff's Volunteer Search & Rescue, Fillmore Mountain Rescue, Team 1

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