Rappelling off the belay loop

sDawg wrote: 

I did not realize some people deliberately rigged their rappel above their heads. For me, near the top of a double-rope rappel, the weight of 2 9.8-ish ropes easily holds my brake for me. I have to pick up 15 pounds of rope above my belay device to lower myself, like when you belay a child at the gym. I am not sure how that would work with the rappel above my head...

Maybe I should have said adjacent to your head, or above.  Either way, grabbing the brake strands at waist level (or anywhere within reach) and lifting will allow you to rappel.

sDawg wrote: I also have long hair, but I use a cool thing called a hair-tie and it keeps my hair far away from my rappel, the rotating machinery/oil/chemicals I work with, and anything else that is not a good place for hair.

Cool story, person who has probably had long hair for a long time.  Maybe you could pass that on to my 14-year-old brother in 1994.  I wish I was one of you people: those born knowing everything from the get-go and not having to rely on real-world experiences to learn and grow.

The belay device has to be up high enough that an autoblock on the belay loop can't collide with the device when the autoblock is loaded.  Test this in a safe place a foot or two off the ground, because when the autoblock is loaded it elongates---this is part of the clamping mechanism---and it is the elongated version that has to clear the device, not the compressed version you tie and rappel with.  How high the device has to be depends partially on the total length of the autoblock and so on how many turns are used.  Make sure you've got yours set right!

After figuring out the distances, I think almost everyone will find the device rides around eye level, but rarely if ever above the head.  The higher the device is, the more difficult it becomes to initiate rappels with anchors that are low relative to a narrow starting ledge, so in general you don't want to rig the device any higher than backup knot clearance requires.

If the ropes are too heavy, lifting them will initiate rappel motion; they do not have to be lifted above the device.

Long hair and beards are a potential problem for almost all device positions, except possibly the highest ones which, as just mentioned, have other problems.  Hair ties and clothing tucks can come undone, so vigilence is always necessary.  If you feed your hair (or loose clothing) into the rappel device, you will have to unweight the device to get you hair out.  Better know how to do this when free-hanging with your head pinned against the rappel plate!k  (A word to the wise: you can't wrap the rope around your foot and step up, because this will continue to weight the device.  And any over-the shoulder slings you are carrying will be trapped unless you have a double-length sling clipped to be removeable without lifting over your head.)

rgold wrote:A word to the wise: you can't wrap the rope around your foot and step up, because this will continue to weight the device.  And any over-the shoulder slings you are carrying will be trapped unless you have a double-length sling clipped to be removeable without lifting over your head.

My sister was showing her daughter just the other day how to clip doubles. It was a way that was removable!

If you're comfortable without a 3rd hand backup, I'd mostly forget about extending - transfering your weight from the anchor to the rappel rig is easier when it's on the belay loop.

2 rare benefits of extended rappel even w/o 3rd hand backup:
 - saddlebags feed easier
 - rotational balance with a pack (or if you're top-heavy)

The reason for rotational balance is interesting.  As rgold pointed out, the argument about the extension changing your center of gravity (repeated by many people and books) is wrong.  The real reason it's easier to keep yourself upright with an extension has to do with the position of your braking hand.  With extension, the point where your braking hand is holding the rope is farther from your center of gravity, so it's easier to create forward-rotation torque with the braking hand by pulling back on the braking side of the rope.

Serge Smirnov wrote: If you're comfortable without a 3rd hand backup, I'd mostly forget about extending - transfering your weight from the anchor to the rappel rig is easier when it's on the belay loop.

2 rare benefits of extended rappel even w/o 3rd hand backup:
 - saddlebags feed easier
 - rotational balance with a pack (or if you're top-heavy)

The reason for rotational balance is interesting.  As rgold pointed out, the argument about the extension changing your center of gravity (repeated by many people and books) is wrong.  The real reason it's easier to keep yourself upright with an extension has to do with the position of your braking hand.  With extension, the point where your braking hand is holding the rope is farther from your center of gravity, so it's easier to create forward-rotation torque with the braking hand by pulling back on the braking side of the rope.

You also get a bit more friction from your device, because the extension makes it possible to get the brake strands at nearly a 180 degree angle from the rope above.

I believe another motivator for moving the backup below the device was that if the prusik-above was too long you could wind up with it out of reach and cinched down tight.   I suppose the answer to that is "don't rappel if you don't know how to ascend", which is probably really good advice now that I think about it.

Some additional benefits to extensions:

* The party can pre-rig, allowing more checking/inspection

* a pre-rigged device fixes both strands, which can then be used for single-strand rappels (handy in a party of three or when one climber only has a grigri).  If using both strands, you can instead avoid knotting one of the ends, which can streamline multi-pitch rappelling

mbk wrote: I believe another motivator for moving the backup below the device was that if the prusik-above was too long you could wind up with it out of reach and cinched down tight.   I suppose the answer to that is "don't rappel if you don't know how to ascend", which is probably really good advice now that I think about it.

That is good advice, but also just don't use a prusik that's too long.

IMO extension only makes sense as part of a backup-below-device system. If your backup is above the device, I don't see any upsides to extending that outweigh the downsides.

Part of the "fresh look" I mentioned in the post above was the idea of installing the autoblock just above the device and clipped to it.  This would simplify everything, eliminate the "too long to reach" issue, and would (I think) allow the device to function as a progress-capture device in case the need to go up arises.  I'm also interested in possibly replacing the autoblock with a Valdotain Tresse, which many arborists seem to prefer.

But as I said the first time around, this is all conjectural at the moment and I haven't had the opportunity to test any of it, so please beware.

I usually don’t back up my raps.  If I do, I’ve used a prusik above the device.  But the Valdotain Tresse in  the manner Rich describes sounds intriguing.

What it looks like with a carabiner or special pulley: 
https://youtu.be/0OKYcUAGAPA

Brief coverage of its nuances.

I don’t always rappel, but when I do, I hold onto the brake line.

Not sure which rap device Rich has in mind.  Or whether a suitable rap device even exists for this.  It is a “fresh look” after all.

But assume that the keeper wire loop of the ATC Guide were strong enough for hanging body weight plus some reasonable margin. And that unexpectedly loading it as below can not pinch / cut the rope strand(s).

1. Rig the Hypothetical ATC Guide (HATCG) for normal rap in high friction mode.
2. Attach the KT on the rope strand(s) above the HATCG.
3. Attach / locker the ends of the KT cord to the large metal eye of the HATCG.
4. Rap while tending the KT just as you would a prussic above your rap device.

When / if you lose control of the rap, and assuming you let the KT lock up and it does, your weight becomes suspended via the ...

braking locker on your belay loop -> keeper wire of the HATCG -> HATCG’s body -> locker in HATCG’s large metal eye -> KT -> rope.

KT might be replaced by any hitch?

When the concept has matured enough and you are on board, send the royalties directly to Rich. :)

Josh Cameron wrote: If you use a dulfersitz I don't think you'll need an autoblock. But for the set-up most Americans use, the ATC attaches to the leg loop and the prusik attaches to the belay loop?

Other way around.

Perhaps I went too far in describing this in practical detail on a thread in the beginner forum.

Bill Lawry wrote: 
But assume that the keeper wire loop of the ATC Guide were strong enough for hanging body weight plus some reasonable margin. And that unexpectedly loading it as below can not pinch / cut the rope strand(s).

I like to think of the keeper wire as approximately as strong as dental floss.

I am guessing that rgold was imagining that the "ear" hole of a guide-style device would be used.

rgold wrote: Part of the "fresh look" I mentioned in the post above was the idea of installing the autoblock just above the device and clipped to it.  This would simplify everything, eliminate the "too long to reach" issue, and would (I think) allow the device to function as a progress-capture device in case the need to go up arises.  I'm also interested in possibly replacing the autoblock with a Valdotain Tresse, which many arborists seem to prefer.

But as I said the first time around, this is all conjectural at the moment and I haven't had the opportunity to test any of it, so please beware.

I was less interested in the Valdotain Tresse because it requires a special piece of kit. But it occurs to me that a) it may be much easier to un-stick, which is my main concern with the Prusik in this scenario, and b) I carry a special piece of kit for my Prusik anyway.

One other concern I have is attaching the backup in a way that doesn't interfere with the functionality of the rappel device. "Guide-mode" devices (ATC Guide, Reverso, DMM Pivot) have a loop for clipping to the anchor, but I wonder if clipping there would pull the device into a position where the friction is changed.

mbk wrote:
I like to think of the keeper wire as approximately as strong as dental floss.

Me too.  And the small metal hole (“ear” hole) is also questionable for this hypothetical application.

I don’t believe Rich even suggested an ATC Guide be used in this way. I would not - and did not. Correction - the small hole is what he was thinking.

I suspect a whole new device design with testing is/are needed before going to such a mode of backing up a rap.

mbk wrote: I am guessing that rgold was imagining that the "ear" hole of a guide-style device would be used.

Yup.

I don't think attaching the prusik to the rappel device solves the "prusik too long" problem.  It actually makes it worse.  Whereas normally (prusik attached to belay loop) "too long" might be >60cm, attaching the prusik to the device (which sits higher than the belay loop) means "too long" is now (for the same person)  >50cm.

It also reduces the prusik's ability to save one in the event of incorrect rap device rigging.  E.g., if one fails to put the rap biner through the rope and fails to weight-test the system before detaching from the anchor.  Admittedly that's 2 mistakes rather than 1, but a prusik attached to the belay loop would save the day in that situation.

Lastly, it would complicate unplanned knot passing (admittedly rare).

IMO teaching people to shorten a long prusik by tying a knot is the best solution to the "prusik too long" problem.

Erroneous Publicus wrote:

So the method that works perfectly for the vast majority of climbers is the least effective of all the perfect methods? That's deep.  

Tell me more about this "works perfectly" thing and your data?

Just because people do something does not mean it is effective when you actually need it to work.

Bill Lawry wrote: Me too.  And the small metal hole (“ear” hole) is also questionable for this hypothetical application.

I don’t believe Rich even suggested an ATC Guide be used in this way. I would not - and did not. Correction - the small hole is what he was thinking.

I suspect a whole new device design with testing is/are needed before going to such a mode of backing up a rap.

Why don't you like the idea of using the "ear hole" to connect a backup?  I don't know their ratings, but I imagine it has to be pretty significant considering it's designed to hold a falling climber (on top rope).  But maybe I'm missing something?

Now I'm curious to look up the ratings on the guide-mode-capable devices.