The auto locking Munter hitch
Note - This post discusses techniques and methods used in vertical rope work. If you do them wrong, you could die. Always practice vertical rope techniques under the supervision of a qualified instructor, and ideally in a progression: from flat ground, to staircase, to vertical close to the ground before you ever try them in a real climbing situation.
An old school yet effective way to belay your second is with a simple Munter hitch. The Munter has one advantage over an auto locking belay device such as a Black Diamond ATC or Petzl Reverso, in that you can easily lower your second if you need to. However, most people think that one of the downsides is that the Munter does not have the nifty auto lock feature that these belay devices offer.
Not so, grasshopper! With this crafty rope trick (CRT) you simply add one carabiner to a Munter hitch to make it autolocking. There are a couple of ways to do this.
Here’s one method. By adding the carabiner, the hitch remains in raising mode, and can't “flip” into lowering mode.
A few things to note:
Let’s start off by saying this is kind of a guide trick, and may not have a lot of utility for recreational climbers.
This knot is best used in situations where the chances of the second needing to be lowered is unlikely. This is a subjective choice that depends entirely on the skill of the climbing team. Also, it should probably not be used on any sort of traverse where you might swing into something vertical or overhanging. If there’s more than a slight chance that the second may need to be lowered, it’s probably better to use a regular Munter hitch or some other belay method.
Let’s start with a few general principles of Munter hitch belay.
As always when using a Munter hitch, it’s best to use a large pear-shaped “HMS” belay carabiner with round metal, which helps minimize friction.
Using a thinner rope or a new one with a sheath that’s a bit slippery works best. I’ve tried it with my ancient 10 mm workhorse rope with a fuzzed up sheath, and it’s quite a bit of work to feed that rope through the hitch.
You want to use two hands. Your”feed” hand pulls in slack rope and the the brake hand simultaneously pulls it down. If you only pull on the brake side of the rope, you’re going to get a lot more friction, do more work than you need to, and potentially get some twists into the rope.
Some specifics of using this hitch in auto lock mode:
You can add or remove this auto lock method into the Munter belay at any point in the pitch when your follower is coming up. For example, if the climbing starts off easy and then gets hard for the final part of the route, you could have your follower in auto lock mode for the easy part, and then simply remove the blocking carabiner when they get to the crux, so you have an option to lower them if necessary.
Or, you can belay mostly without the auto lock. If you need to put on a jacket, sort out the ropes, take a photo, whatever, you can put it into lock mode, do your business, and then remove the locker and go back to normal. Can't do that with any other type of belay device that I can think of.
Be sure the hitch is set up in “raise” mode before you clip the blocking carabiner.
Test this before your follower begins, to be sure it is locking up properly.
One handy use for this knot is for light hauling, such as a backpack or light haul bag. The blocking function serves to capture the progress of your haul. Typically, another semi-obscure knot called the garda hitch would be used in this situation, but many people find this knot to be, shall we say, temperamental.
Another use of the auto locking munter hitch is to climb a rope. If you're short on gear, like a plaquette style device (Reverso), Grigri, extra friction hitch, etc., the auto lock munter can be your progress capture on your harness. This is definitely a trick use of the knot and something you wanna practice in a controlled environment before you ever use it for real!
This knot suffers from the same general problem as a standard plaquette device like the Petzl Reverso: if your follower is weighting the rope and needs to be lowered, you can’t easily do so.
By far the easiest way to transition to lowering mode is to have your follower unweight the rope just enough for you to unclip the blocking carabiner from the load strand. Once the carabiner is gone, you’re back to a normal Munter hitch, and can easily lower your follower.
If that’s not possible, there is in fact a way to release this when loaded. Use a small locking carabiner for the blocking carabiner. Unclip the loaded rope from the blocking carabiner. This should allow the hitch to flip into lowering mode, and the small carabiner should pass through the large carabiner. Having a third hand autoblock backup on the brake strand before you do this is highly recommended. Yes, this is kind of clunky, and it's probably better to avoid that situation in the first place, but it is possible.
As stated clearly at the top of this post, please practice this in a controlled environment before you ever do it in real life!
Here's a nice video on how to do this.
Here’s a second method, which results in less friction. Depending on your rope, this might be a big help. Watch the video for the whole scoop. (Start about 2:00 for the action.)
At first glance it looks like a bit of a mess, but it works remarkably well.
