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How to Build a V-Thread Anchor   

Tagged in: Anchors, Ice Climbing, Rappelling
by Cory Akin
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Build a V-Thread in 9 Steps 

Rappelling on ice, when there are no manmade anchors, requires a bit of ingenuity. You can use ice screws or nuts/cams if thereís rock, but then you are forced to leave your gear behind. Not only does this take a toll on your wallet and junk up the wilderness, but after enough rappels, you will find yourself out of gear, maybe even before the rappelling is over.

The key to rappelling multi-pitch ice in the backcountry, then, is the V-thread, or Abalakov thread. While the thought of using ice as a rappel anchor seems initially daunting, scores of in-field tests and observations have shown that a properly constructed V-thread placed in good blue ice provides more than enough strength and support for safe rappelling.

Hereís the run-down for constructing a V-thread ice anchor as pictured and instructed by San Juan Mountain Guide Pat Ormond.

Make your V-Thread in thick, blue ice. Any other frozen medium, such as verglas (very thin ice sitting on a rock slab) or neve (hard, old snow) needs to be entirely avoided as only good, solid ice should be trusted to support your body weight on rappel.

Once youíve found a solid spot, smooth out an area with the adze on your ice axe, chipping away the brittle ice sitting on the surface to reveal the stronger ice beneath it.

Take a 22cm ice screw and begin the first hole somewhere between 45 degrees and 60 degrees from the plane of the ice (60 degrees offers the maximum volume of ice between both channels, although a 45-degree angle is plenty sufficient). After completely burying the first screw, back it out a few cm, but not all the way. The first screw will serve as a guide for the next placement.
V-Thread Step 3
V-Thread Step 3

V-Thread Step 4

V-Thread Step 4
Take another 22cm ice screw, and begin the next hole to the side of the first one, also at a 45-degree angle, aimed toward the other screw placement. Given that ice tends to shear along a horizontal plane (side to side), begin the second screw slightly higher than the other. Line up the placement, and bury the screw as far as it goes, intersecting the first channel.

You can now back out both screws and clean the holes with your ice tool. Ice tools for fishing out the cord/rope can either be purchased pre-made and are basically a skinny wire with a hook on the end, meant for grabbing the tip of the rope. Or, for a cheap but effective alternative, you can make one with a clothes hanger. Simply cut a branch off a clothes hanger, and bend one of the ends to form a hook. If you cut the end at a diagonal, the sharp point will make it easier to catch the tip of the cord/rope.

Once the channels are cleaned out, you have two options for anchoring into the V-thread. First option is to fish a length of accessory cord through the channels. If you use this method, tie the cord together with a double fishermanís knot to ensure your ends stay together. You can then run the rope through the chord and prepare the rappel. In this situation, you will complete the rappel, pull the rope through, and leave the cord in the V-thread.

The second option is to fish the rope itself through the V-thread. As you did with the accessory cord, use your ice tool to finagle the rope through the hole. Then pull the rope until its middle is sitting within the V-thread. Using this method allows you to completely clean the route, leaving nothing behind except for the V-thread.
V-Thread Step 6A
V-Thread Step 6A

V-Thread Step 6B
V-Thread Step 6B

Once you have rope through either the accessory cord or the V-thread itself, sink an ice screw above the V-thread with a quickdraw attached. The purpose of the ice screw and quickdraw is to provide a back-up anchor, just in case the V-thread fails. You donít want the quickdraw to be weighted in any way when the first person rappels, since ultimately you are relying on the ice to hold your weight. Once it is the last personís turn to rappel, the screw and quickdraw are removed and placed back on that personís harness.
V-Thread Step 7
V-Thread Step 7

V-Thread Step 8

V-Thread Step 8

Before fully committing to the rappel, pull on the V-thread with enough force to ensure it is able to withstand a personís body weight. As long as it checks out, with the back-up ice screw and quickdraw in place, have the heaviest person in the group go first on the rappelóthis offers the group feedback on the strength of the V-thread.

When it comes time for the last person to rappel, as previously mentioned, the back-up ice screw is removed and the rappel is completed. The rope will then be able to easily slide through the channels as it is pulled free for either the next rappel or for the walk home on flatter terrain.

Keep in mind that when constructing a V-thread anchor, even on a single-pitch rappel, you can always set up two V-threads in the same station to provide extra security. As mentioned, set them vertically to each other, seeing as you do not want both V-threads to fail simultaneously on a horizontal plane of ice.

Before doing anything in the backcountry where your life depends on the construction of the V-thread, practice on an ice patch next to the parking lot where you won’t need to rappel. Have multiple people pull against the thread while chipping away at the ice to get an idea of how strong or weak the thread can be. Practice as much as possible so that when it comes to using a V-thread on a climb, you will feel dialed.

View the original article on backcountry.com.

Next Topic » Managing Ropes on Snowy Ice Climbs

Comments on How to Build a V-Thread Anchor Add Comment
By Hutash
Nov 21, 2014
I am missing something...how does using two V-threads work?
By Mike J Barter
From: Banff, Alberta
Nov 23, 2014
I would be a little careful about running the rope through the V-thread it's self. In a really cold environment you are taking a chance freezing a wet rope into the thread and making retrieval impossible. While this works fine in theory so does communism.
Placing the rope through also means the you have to get the intersection of the two screw holes spot on. Often resulting in a shallower anchor. This is much like the ice screws placed in a positive direction ( downward) you hear it's stronger but you rarely if ever see it done in the wild.
By Warbonnet
From: Utah, India and Cambodia
Feb 26, 2015
Based on an uber-climber's suggestion, years ago I switched to a horizontally-placed "V" (or Abalokov) thread and instead placed (and still do under most circumstances) an "Anderson thread" which actually is NOT a vertical "V" thread. I know you know the difference. I fully take your point re: getting iced ropes stuck such that they are difficult to pull (can be more than difficult). The "A" thread (for those that do not know) is NOT an Abalokov -- even though they both begin with the letter "A". To build an "A", the configuration is such that the 'top' hole (drilled downwards - negative orientation) is done with a shorter screw (say a 19 or less -- no stubbies). The bottom hole drilled upwards (positive orientation) should be (ideally) with a 22 cm (or longer than the top hole). As such, looking sideways, it does not result in a 'triangle' as a "V" thread does, rather, an offset configuration. Both holes are aligned top to bottom (although some offset one hole slightly, say by an inch or two) and like a "V" thread, the holes meet (taking care that one hole is not drilled too far past the other one, otherwise, the rope will "dead end" when trying to fish it thorough. To greatly ease the pull at the lower rap station as well as to facilitate threading the rope through the system, once the rope is fished through the top hole and out the bottom one, take both ends and "floss" the junction to remove the sharper bend which will occur when the two screw holes meet. To make the pull even easier, take a screw & saw the hole entries back and forth to remove a possible sharp ice edge. Basically, you are building a "greased lightning" system. To be even stronger ("A"s have been shown numerous times to be stronger than "V"s), one can build a "double A" -- one on top of the other and snake the rope through both sets of holes. Sounds laborious but not so: once mastered, a single Anderson can be built faster than a "V" due to the flossing and hence, the "glide"of the downward pulled rope. Anderson's also ice up less than a "V" for obvious physics reasons. Under some circumstances, an "A" can be used as the primary anchor and a "V" as a backup (if weird conditions are encountered and a double "A" cannot be constructed.
One A (Anderson) thread, side view
One A (Anderson) thread, side view

Anderson thread (vertical side view)
Anderson thread (vertical side view)

More detailed double "A" thread configur...
More detailed double "A" thread configuration
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