Abalakov thread
Abalakov thread, named after great Soviet climber Vitaly Abalakov, is one of the great mountain safety inventions. It's also known as a V-thread. Generally speaking Abalakov thread is fairly easy to create, doesn't require any expensive gear to be left behind and, when created and used properly, it's safe.
== You need: ==
- 1-2 meters of >7mm prusik cord or something else with similar strength. The length depends on how you use it. If you use it traditional way, you need about 1 meter. A narrow dyneema sling will do also, but is far more expensive.
- At least one long, >19cm, sharp ice screw. If you have longer screws, use the longer one. Length of screw adds security.
- Abalakov threading device, either improvised or commercial.
- Knowledge to create double fisherman's knot, or other dependable knot according to material you're using.
== Step-by-step instructions: ==
- Select location with solid ice and remove all excess ice from area of 20-40cm in diameter.
- Use your ice screw to drill horizontal hole at roughly 45 -50 degrees compared to the surface of the ice.
- Measure a suitable distance for the second hole (15-20cm), you can use your ice screw as a guide. Note that wider the gap between holes, stronger Abalakov you've got. Roughly spoken 10cm gap, will result strength of 6-7Kn, 15cm gap 10-11Kn and 20cm gap 11-12Kn.
- Drill second hole to the ice with similar angle, so that the two holes meet as deep inside the ice as possible. If you put second ice screw or the Abalakov threading device in to the hole, it's easier to aim in to right spot.
- Put the cord (or in my case prusik loop) in to one of the holes as deep as it goes.
- Use Abalakov threading device to pull the cord trough from other hole.
- In case of prusik loop or sling, you're ready to put your abseiling rope trough, in case of untied cord; you need to do a double fisherman's knot to be ready.
- Place the screw in to ice about 50-70 cm away from Abalakov you've just did and use a runner to create a backup for first one to abseil (last one will remove it and abseil with out backup).
- Run half of your rope trough the cord loop you have. Now the first one to abseil can prepare him/herself to go down. First one should carry most of the heavy gear.
- Watch carefully while going down to observe behavior of the ice for fractures and prusik loop for possible slippage (it won't slip though, if you did the knot right).
- Once first one is down, he/she can start creating the Abalakov for next pitch, while the second one removes the backup and abseils.
In case you don't have good enough ice available, you could use two Abalakovs instead of one and create a balanced abseiling point. This being said, one should heavily consider a possibility for other route down in this type of circumstances.