Portable Anchors – Bipods, Tripods, Gin Poles, and Quads
As rope rescue technicians, we learn early to look for that perfect high-point anchor. You know the one. It’s easy to sling, positioned perfectly in line with the portal and the rescue system, and rated for the anticipated load. We all know that they can be elusive, to say the least.
In locating high-point anchors, we learn to first look straight up for an anchor strong enough and high enough to allow us to clear a vertical litter out of a space (requires about 9 feet). Then we look left and right. Are there beams or substantial anchors high enough and positioned to allow a high-point bridle for our lift? Or maybe there’s an anchor positioned were we may be able to “cowboy” a rope up and over a beam and adjust our end-of-line knot at the appropriate height; and then tie it back to another anchor (extended anchor technique).
But what about those times where we need a high-point anchor, and there is nothing, nada, zilch? No beams, trees, nothing! That’s when we bring our own high-point, also called a portable anchor.
Portable anchors come in a variety of configurations, the most common being tripods. Even tripods are not all created the same. Some are rated only for equipment, others have different allowable working loads, and they come in a variety of heights.
There is also the option for bipods, quadpods, monopods (gin poles) and some devices that can transform into all of these configurations. They can be centered over a portal for straight, vertical lifts (tripods/quadpods), straddle the plumb line (bipods), or provide a single high-point in an area with a small foot print (monopods). They can even be designed to cantilever out over an edge to provide a clear path for the ropes and ultimately the rescue package. Determining which one to use would be based on your team’s needs and your type of response area.
So, let’s talk about some of the portable anchors that we like to use, including their capabilities and limitations.
The SKED-EVAC® Tripod is a simple tubular aluminum tripod with cast header and feet. It extends to a maximum height of 10 feet at the anchor connection points, which gives a good bit of clearance for vertical litters to clear the bottom edge. At full extension (10 feet), the tripod is proof loaded to 5,280 pounds. The SKED tripod is simple to set up, includes a chain to run through the feet to keep the load stresses off the cast header, includes three anchor points, and adjusts in height for situations where there isn’t enough headroom for full extension.
Eccentric Loading and Resultant Forces
Tripods as well as other portable anchors must be respected when it comes to the “direction of pull” on the rescue system and the relationship to the position of the load. Here are a few terms to be familiar with:
• Axial loading: The object is loaded in line with the normal fixed axis point (the center of a tripod, equal force on all legs).
• Eccentric loading: The load is no longer axial and is offset from the axis point. (The system puts side-load forces on the anchor, or the load is moved out from under the axis point.)
• Resultant: This is the relationship between forces acting on an object. (It is the relationship between the load and the vectoring forces of the rescue system from the portable high-point; it is the bisection of this angle.)
The “rule of thumb” for tripods is the resultant forces must remain inside the footprint of the tripod. That is, if the rescue load is pulling straight down (plumb/axial), and the rescue system vectoring forces are angled outside of the footprint of the tripod, then where does the bisection of that angle fall?
Imagine drawing a circle that connects the legs of the tripod. As long as the load and the rescue system remain inside that circle, the resultant will be acceptable, and the tripod will remain axially loaded and not tip over.
There are some techniques to overcome this limitation such as a directional pulley located within the footprint of the tripod. Another technique, which we call the “Pass Through” method (see illustration at bottom), allows counter acting resultant forces to stabilize the tripod. If your haul line is angled too far outside the footprint of the tripod, or the load is moved outside the tripod footprint, the entire tripod is at risk of toppling over (eccentric loading), which could spell disaster.
So, to keep things simple, we often recommend that all lines are kept within the footprint or to add a low directional within the footprint. This provides a small margin for error when hauling or setting up a directional. Technically, you can set up the directional outside the footprint (or pull the haul line outside the footprint) as long as the resultant force is still inside.
Just remember to envision all lines as though they were loaded before you load the system. We’ve seen plenty of low directionals that were set up perfectly; however, the anchor strap actually allowed them to fall outside the footprint once loaded. As we like to say, "keep it safe and simple!"(KISS) And to play it safe, keep all lines within the footprint.
Multi-Use Portable Anchors
Portable anchors have progressed way beyond the tried-and-true tripods. We are seeing some pretty versatile systems that can be configured as quadpods, bipods, even monopods. These modern systems provide capabilities that go beyond straight vertical lifts while straddling the hole or entry into the rescue subject’s location.
As with most devices that provide additional or alternate capabilities such as monopods and bipods, they are generally more complex and require additional training to fully understand the forces being applied. The ability to extend an anchor point out over the edge of a containment berm, or a cliff edge in a wilderness rescue, will greatly reduce friction on haul lines and reduce rope abrasion, providing clear movement of the rescue package coming up or going down over the edge. This is something that a tripod just cannot provide. But a better mastery of the effects and relationships of the forces being applied needs to be obtained. Understanding and identifying the resultant force is critical in these situations.
These new generation multi-purpose devices, such as the TerrAdaptor™ or the Arizona Vortex, are designed to be used as tripods, bipods, monopods; or in the case of the TerrAdaptor, as a quadpod. They are third party (UL) certified to NFPA 1983 in symmetric tripod and quad-pod configurations. In addition to the straight vertical capabilities, these devices also provide an “over-the-edge” capability.
For tight areas such as on catwalks, the A-Frame configuration or bipod can provide that portable high-point where a tripod just can’t fit. For extremely tight quarters or when lightweight gear is needed, they can be rigged as a monopod or gin pole. This requires some advanced knowledge of rigging and tiebacks; but, rigged correctly, it provides high strength and a high-point in places no other system would fit.
Sometimes the configuration of the structure or the height of your portable anchor does not allow enough overhead to clear the foot-end of a vertical litter. In instances like this, you may need a simple mechanical advantage assist that is attached low on the litter, or a modified Pick & Pivot technique where the lifting point on the litter is changed from the head to the feet once the litter reaches an edge to allow recovery.
Smaller, Lighter, Stronger
To meet the demands of the USAF Pararescuemen (PJs), Roco worked with Skedco to develop the Roco Tactical Mini-Tripod.
Reaching about 5 feet at maximum extension with removable legs, it is small enough to carry in the team’s rucksacks, if needed. Its short height also makes it the strongest rescue tripod on the market. Additionally, the removable legs provide the ability to use it as a bipod or A-frame.
Utilizing some simple techniques, a vertical litter patient can be removed from a space with the Roco Mini-Tripod just as easily as with a full-size.
The lighter weight, compact size, and full functionality allow teams with limited manpower and resources to operate without limited capabilities.
It is important to know what your needs are regarding portable high-point anchors. Complete your rescue preplans. And, if they reveal the need to cantilever out over an edge, or that a bi- or monopod may be required, you may want to consider a multi-functional, portable high-point system that provides capabilities beyond a tripod. Whichever device you choose, always make sure you get the proper training. The unexpected loss of a high-point during training or a rescue could be disastrous. So, be safe, know your equipment and know how to use it.
Check out our selection of tripods in our Gear Shop; or, if you need additional training, review our listing of courses. If you would like to speak with one of our instructors, please call us at 800-647-7626 or email info@RocoRescue.com.
Here are several tripod techniques from our new Roco Pocket Guide.
Simple B&T M/A with bottom directional.
High-point pulley & bottom directional used with piggyback or Z-rig M/A systems.
Pass-through technique used with piggyback or Z-rig M/A systems.