The right (and wrong) ways to backup a V thread anchor
Photos from Tim Banfield @timbanfield and article (used with permission) are from Sean Isaac. Sean is an ACMG (Association of Canadian Mountain Guides) certified Alpine guide, a former professional climber, and author of the “Ice Leader Field Handbook” and “How to Ice Climb” (2nd ed.) Follow @seanisaacguiding and @howtoiceclimb for more great tech tips.
Learn this and much more on Sean’s Ice Leader Camps and Ice Series Clinics through Yamnuska Mountain Adventures @yamnuskamtnadv.
PHOTO CREDIT: @TIMBANFIELD AND @SEANISAACGUIDING
Hopefully this is obvious, but this is for RAPPEL ONLY. You should NEVER top rope through cord like this, the friction from the weighted rope could cut through the cord!
Sean writes:
“V-threads (invented by Soviet climber Vitaly Abalakov) are used for rappelling on ice when fixed anchors like bolts or trees are not present. Like any anchor, redundancy is important, so rappelling from two equalized V-threads might make sense in some situations. These can be equalized to a master point or simply in series where one takes the load while the other exists as a backup. Unfortunately, this would also mean leaving behind a lot of cord that ultimately becomes garbage.
With experience, it is acceptable to rappel off a single V-thread, but always implement an unweighted backup anchor clipped loosely to the rappel rope for the first person(s) down to fully test the V-thread. The last person to rappel removes the unweighted backup, relying only on the tested V-thread.
The V-thread backup must be clipped to the rappel rope and not to the V-thread cord. A locker draw is very useful for the backup as long as the length is satisfactory. It also must be slack enough that it does not take any weight, but not so slack that if the V-thread were to fail there would be a major shock load to the backup anchor.
No-threads—also called zero threads or naked threads—are V-threads where the rope is fed directly through the bored holes, eliminating the need for leaving cord behind. This is environmentally more friendly but should only be done in dry ice to prevent the ropes from freezing in place. No threads also need an unweighted backup to test its integrity.”
What about using just one screw as a backup?
“We often see parties using a one screw connection point where the entire team anchors to on a descent. Think about the weight here, the medium we are in, and the issues that may present. Does it hold, yes, but are there great security margins here for the medium we are on? We'd say no. Incorporating another screw to build a stronger anchor it takes seconds and significantly increases the team security.”
Let's look at a few examples.
Here's the right way to do it.
The backup is two screws, statically equalized.
It has a locker draw, for extra security.
It's clipped to the climbing rope, not the thread.
It's clipped with minimal slack.
photo credit: @timbanfield and @seanisaacguiding
The same principle applies for a no thread / naked thread anchor, where the rope goes directly through the ice instead of cord.
photo credit: @timbanfield and @seanisaacguiding
Now, some common mistakes . . .
Whoops! Backup is clipped to the threaded cord, not the rope. Initially this might not appear to be a problem. However, if the V thread fails, your backup, and thus you, are putting a sudden large load on some 6-ish mm static cord, rather than the larger diameter, stretchy dynamic rope. Better to remove the this cord altogether, and clip the back up directly to the rope.
PHOTO CREDIT: @TIMBANFIELD AND @SEANISAACGUIDING
Whoops! Backup is partially holding the weight of the climber, instead of having the full weight on the thread. This never properly tests the anchor for the last person.
PHOTO CREDIT: @TIMBANFIELD AND @SEANISAACGUIDING
Whoops! The backup is too long. If the thread fails, you could have a big shock load on that sling.
PHOTO CREDIT: @TIMBANFIELD AND @SEANISAACGUIDING
