Critique my rappel extension

Guy Keeseewrote:

...

I come from the school of fastest is best/safest method.

well fastest is to simply jump so...    

To me, one of the key benefits of the third hand is... I put it on first, pull up some rope to create some slack which makes it a breeze to thread my ATC.   

Eric Craig wrote:

• Also, adding an extension does not lower a person's center of gravity,  period. Putting on a heavier harness, or adding even more gear to it, putting on heavier shoes, etc., will lower your center of gravity. Assuming whatever position you are in has your  feet  lower than your head. If your head is lower than  your feet,  then you would want to take your harness and/or shoes off to lower your center of gravity. Or put on a heavy helmet. 
• Even putting on an old school UIAA full body harness with a center of chest tie in will not raise your center of gravity  (ok. Yes it will,  a tiny inconsequential amount,  because of the added webbing and thread above your center of gravity. )
• You can lower or raise your support point (tie on) in relation to your center of gravity. 

The above is correct. An extension does not change a person's center of gravity. What an extension does is increase the braking angle as well as the increase the braking lever arm. These combined give greater braking friction as well as finer braking control.

Guy Keeseewrote:

As someone who had to save a fellow who couldn’t reach the 3rd hand when it grabbed, inadvertently, and left him hanging. I always wonder “who came up with this?”.

That's why the recommended method is to put the third hand backup below the belay device, not above it.  The method you describe (friction hitch above the belay device) hasn't been the normal method for several decades.  Cosley and Houston (2004) describe using the third hand below the device (see page 182-189 for details).  They also describe rappel extensions in this section.  In other words, this is not a newfangled technique.

As an aside, I might consider putting a third hand above the rappel device (with device on belay loop) if I anticipate needing to pass a knot on rappel. 

I think that a point of clarification is needed in a lot of the center of mass commentary. None of you are thinking in the correct reference frame. With respect to the ground when one is standing, the location of the rappel device is meaningless. However, when you are on rappel, the device is the reference point. Think about a free hanging rappel, all the forces are going through the device and up the rope. In this scenario, extending the rappel device will increase the distance between the device and your bodies center of mass. This increase in distance will make it so that your body will hang directly below the device in a more comfortable manner. Both extended and off the belay loop are fine in most situations. Learn what the odd situations are, like having a heavy pack, and learn to mitigate against their pitfalls, like extending your rappel or tethering the pack below you.

Shane Fwrote:

I think that a point of clarification is needed in a lot of the center of mass commentary….

Agree.  The point is that extending (raising) the belay device makes it easier by raising the “center of effort”.   True that the center of mass itself doesn’t change but this is mostly along the lines of “ACKCHYUALLY…..”  and largely irrelevant to the point  or takeaway. 

Mark Pilatewrote:

Agree.  The point is that extending (raising) the belay device makes it easier by raising the “center of effort”.   True that the center of mass itself doesn’t change but this is mostly along the lines of “ACKCHYUALLY…..”  and largely irrelevant to the point  or takeaway. 

I agree with you that my comment was an "ACKCHYUALLY..." type comment. I am an engineer so, it kind of comes naturally to me!

Back to the original post, can someone explain why more people don’t simply strip a quickdraw for the extension? I don’t think I’m ever on a wall with no QDs. I also always have one spare locker. Ergo, strip the wiregates off the qd, locker on fixed side of qd, clipped to belay loop, and rap device biner goes in loose/open end of qd.  

Was taught early the value of not carrying single use equipment, so it seems to be more efficient to use items I already carry (for reference, I only carry contact slings and don’t feel like knotting them, esp if I have a qd of useful length)

I find the autoblock backup below the device useful when rapelling lower angle stuff where it's unlikely the ropes were tossed successfully all the way to the bottom or when I have to clean stuff on the way down. Faffing with the rope or gear while on rappel is nicer with a backup.

Regarding “center of mass”: CM really has nothing to do with it.  If your device is extended, both your hands can be on the brake strands at or near your chest. This is higher than off the belay loop. This configuration allows you to more easily hold your body upright while ONLY holding the brake strands, as opposed to one hand on the brake strands and one hand above the device. Not needed, but I THINK this is what people are talking about. Additionally, the high position of the device allows for the brake strands to be pulled down into a strong 0 degree angle for maximum braking force. Again, not needed for safe rapping, but I think this is something people are talking about.

Another “benefit” of the extension is for pre-rigging or stacking people on a rap. SOP in the guiding world…. If you pre-rig your raps but don't have them extended, you run the risk of getting pulled all over if the stance isn’t right. Pre-rigged just isn’t very comfortable without an extension. This is obviously grown out of the guiding world because a guide would not generally allow a client to load their setup unsupervised.

Last thought: if rapping down to a station you can’t see/in unknown terrain, an extension will allow you to flip your arc guide to a progress capture/ascension configuration with the addition of one carabiner. If I think I’m on a more “exploratory” rap, I’ll definitely extend because it makes going up really simple. 

Not saying there is a correct way. Just trying to clarify. 

Evan Kirkwrote:

Last thought: if rapping down to a station you can’t see/in unknown terrain, an extension will allow you to flip your arc guide to a progress capture/ascension configuration with the addition of one carabiner. If I think I’m on a more “exploratory” rap, I’ll definitely extend because it makes going up really simple. 

I'd argue that if you know there's a good chance you're going up it's easier to rap unextended with a prussic above the device, transitioning to ascent is as simple as popping the ATC out of the system and putting a foot prussic on, you can do the whole thing totally freehanging, no tension transfer needed, switching to the ATC in progress capture you would need to unweight the system, either on a ledge or with a prussic... 

I am not saying either is right or wrong, just making  the point that there shouldn't be an "always" when it comes to extending the device and where you put a prussic, if you use one, being dogmatic about one approach or the other is likely to cause you a bunch of extra effort at some point that could be avoided by considering what is going to work best for the rap you are on right now...

The good ole locker draw is my favorite idiot proof rap extension lately. It also lends itself to several other idiot proof applications. Outside the weight of a single extra dogbone; i can’t see much argument in the way of it being a waste of space on your harness. It’s just a clean way to rack two lockers which is pretty standard kit

Shane Fwrote:

I agree with you that my comment was an "ACKCHYUALLY..." type comment. I am an engineer so, it kind of comes naturally to me!

Haha, sorry.  I actually meant the center mass critiques were “ACKCHYUALLY” type symantic hair splitting….but then that’s also what I’m doing here, so there’s that.   I guess us engineers just try to out “ackchyually” each other most of the time :)

(I’ll post an answer here and geek diagram later when I have time to answer Eric’s question, if no one else does by then)

A very simple extension consisting of a girth hitched double length sling w/overhand knot in the middle and locker at the free end has become my staple for rappelling. It requires no or an insignificant amount of extra time to set up and has greatly increased my safety and ability to work any issues that arise on rappel (when used with a prussik below ATC, also my go-to.) I appreciate the beauty of choosing your own adventure when it comes to risk management, both up and down the rock.

Grant Kleeveswrote:

I'd argue that if you know there's a good chance you're going up it's easier to rap unextended with a prussic above the device, transitioning to ascent is as simple as popping the ATC out of the system and putting a foot prussic on, you can do the whole thing totally freehanging, no tension transfer needed, switching to the ATC in progress capture you would need to unweight the system, either on a ledge or with a prussic... 

With the rappel extended, you just put the foot loop on, then you stand in it and pop the device into progress capture mode.  No need to unweight anything on a ledge, aside from the standing in the foot loop you're going to do while ascending anyway.

Shown nicely around 3:00 here: https://youtu.be/zBRHGv_e78I?si=9EWBBK8uhrHhKf5v&t=179

I've been using an autoblock third hand on the leg loop and a 12" extension off the belay loop for 20 years. I tried the prussik above the ATC, that's the worst (have to manage it carefully, and it's a pain if it locks inadvertently) and I'd only use that if passing a knot, but if I expected that I'd bring a jumar instead. I tried the prussik below the ATC (like most people do nowadays) and I don't like not being able to keep an eye on the third hand and end of the ropes at the same time, and I didn't like the extension that long. With a third hand on the leg loop I can look over down and see the third hand and the rope below it, and manage the rope if I need to shake out some twist before they enter the third hand. The autoblock is like wearing a glove so the rope doesn't rub on my hand. If I let go it provides the perfect amount of friction to stop my descent and I can take photos, shake out the rope, etc. People say the main drawback is the autoblock can hit the ATC and be defeated but I've tested that and the way I do it (3-4 wraps of 6mm cord around the rope, girth hitched on a leg loop, with an extension on the belay loop it was almost impossible to make that happen. I'd have to hang upside down and pull my kneed to my chest, and even then there'd still be a fair amount of friction.

Eric Craig wrote:

I am sorry but I don't understand the braking angle or braking lever arm you are referring to. 

Braking angle == the angle* between the rope and the ATC (or other device)

Braking lever arm == the distance between the brake hand and the ATC (or other device)

Think of it this way. With an extension the ATC (or other device) is further away from one's body thus provides more "clearance" for moving the brake hand around. That clearance results in an increased breaking angle and increased breaking lever. 

*When the rope runs through the ATC and back in the same direction forming a "U" that is zero degrees.

*When the rope runs through the ATC and back but in the opposite direction that is 180 degrees. 

The best solution would be for everyone to buy a Smart Alpine, but Mammut apparently thought it would be fun to tease us with the finest rappelling device known to man and then discontinue it. 

But anyway, the extended rappel is hardly any more work and is slightly safer than the third hand through the leg loop method. I know multiple people who accidentally let go while they were rappelling (in each case they bumped their elbows hard which they say caused an involuntary opening of their hand on the brake strands) and only avoided accidents because of the third hand. Using some form of a third hand if you use a non auto locking rappel device is now taught as standard operating procedure from every climbing educator that I know of, and the rappel extension is taught alongside it because it is safer than the leg loop method and significantly more convenient and enjoyable to use during rappel as well. 

I did a 100 foot rappel the other day. My center of gravity felt really high. So I did a 200 foot rappel the next day and somehow magically my center of gravity moved down. 

For the people taking the stance that going without a third hand is dangerous... here are my thoughts about it:

• Rigging the rap is slower and so is actually rapping- I often climb in a party of 3 so this is compounded here, and especially if you have many raps or one climber is particularly slow at doing their third hand, they can just not be first and not use one. Spending hours getting down a rap route can be dangerous too...
• It is more difficult to rescue a person if they somehow get stuck partway down (yes, unlikely to happen but worth considering if you tend to take inexperienced climbers with you)
• Unless you're the first person down, someone can give you a fireman's which is just as safe, simpler, and generally faster

I'm pro-extension though since I also like to pre-rig my raps.