Rappelling with brake hand on autoblock

I've seen this taught to new climbers as an efficient way to keep the autoblock open while rapping. My gut says to tend the autoblock with my left(non dominant) hand, while controlling the descent with my right(dominant) hand below the autoblock. Is there a clear reason to do either or? 

I should clarify I'm referring to an extended rappel 

Yeah I do just like you. Never felt comfortable with autoblock on brake hand.
If you don't have it extended and use a leg loop, you have to use the brake hand to control the autoblock.

Youtube educational academy strikes again 

Brake hand should be controlling the rappel, and just like belaying. You should maintain a loose "grip" for tending the autoblock with our other hand (for instance, two fingers on top to prevent lock-up), and practice removing your tending hand in the event of rockfall (to train yourself not to lock-up on the autoblock). As always, you should test the system to ensure the autoblock works before committing to a rappel.

Igor Chained wrote: If you don't have it extended and use a leg loop, you have to use the brake hand to control the autoblock.

No you don't, unless you're a tyrannosaur.

Now I need to have both hands on the brake?!?!?

Aren't both hands on the brake side of the extension anyways? They are when I rappel. I'm fairly new to things but the way I was taught to extend would make hard to have one hand on the anchor side. So if both are on the brake then it doesn't matter if one's on the auto block. Right? 

I always found the most often experienced benefit of the auto block is preventing ropeburn on my brake hand... Is it really the preferred  method to have one hand tending the auto block and the other controlling the descent?

Jay dee at least one hand needs to be on the auto block for you to be able to descend, or else your autoblock is too loose.

Ryan M Moore wrote:Is it really the preferred  method to have one hand tending the auto block and the other controlling the descent?

Yes, though the situations are edge cases:

1. Rappeller panics during descent, losing control, and defeats the autoblock by overtending. I think this is the least likely scenario; or,
2. Rappeller is defeating autoblock with brake hand or overgripping with tending hand, and is hit by rockfall, with subsequent reflexive posturing that may continue to defeat the autoblock without applying adequate braking force.

I guess both of those are possibilities, although I’m fairly unconcerned about the first one, I rap enough w/o an auto block cleaning single pitch sport routes that my instinct in a panic would be to put my other hand on the rope.
I also have fairly large hands that well extend over both sides of my autoblock so if I’m overgripping the autoblock reflexively in either a panic or in reaction to being struck by a rock, I think the margin of gripping tight enough to override the block, but not to brake the rappel is a relatively small window, for me at least.

Ryan M Moore wrote:

Jay dee at least one hand needs to be on the auto block for you to be able to descend, or else your autoblock is too loose.

I agree. But they are both "technically" brake hands as they are on the break side of the ATC. This makes the original question seem moot doesn't it?  Or am I missing something? 

Has there ever been an accident where a rappel autoblock failed?

Yes.  People have had them get sucked into their devices and have lost control after inverting.

Anyways...the “brake hand” is whatever hand happens to be on the brake.  Stop overthinking it.  You’ll have two hands on the rope going down; one should be on the knot to keep it moving, one on the rope.

Jay Dee wrote:

I agree. But they are both "technically" brake hands as they are on the break side of the ATC. This makes the original question seem moot doesn't it?  Or am I missing something? 

How to spell brake?

The instance I was thinking of was having your primary brake hand to the rope be wrapped around the autoblock. Perhaps both hands together over the autoblock. To quote an instructor I saw "put your brake hand on the auto block. That way you can keep it pulled back while controlling your descent".  In my meddling with gear I found that my hollow lock didn't grip the rope enough to give me good purchase on the rope while it was loose. 

Put the prusik above the device and use left hand to tend the knot and tight hand on the brake strand. This allows you to rappel care free in addition to the ability to ascend as well and capture your progress. 

Mongoclimb wrote: The instance I was thinking of was having your primary brake hand to the rope be wrapped around the autoblock. Perhaps both hands together over the autoblock. To quote an instructor I saw "put your brake hand on the auto block. That way you can keep it pulled back while controlling your descent".  

Yeah but you could also do that with your free hand with less risk of defeating the block if you lost control of the brake.

In my meddling with gear I found that my hollow lock didn't grip the rope enough to give me good purchase on the rope while it was loose. 

Practice some more - a Sterling hollow block is a pretty reliable friction hitch.

Kelley Gilleran wrote:                                                                                                                                                                                                                                                                                  Put the prusik above the device and use left hand to tend the knot and tight hand on the brake strand. This allows you to rappel care free in addition to the ability to ascend as well and capture your progress.

The purpose of a back-up is to apply braking force to brake strand, not take body weight. Unless you know you will need to ascend the line again, there are no advantaged to putting it above the device, and several disadvantages:

• More likely the friction hitch gets out of reach;
• More difficult to release the friction hitch if you weight it; and,
• Less able to control brake strand. (1-hand versus two hands).

FosterK wrote: Yeah but you could also do that with your free hand with less risk of defeating the block if you lost control of the brake.

Practice some more - a Sterling hollow block is a pretty reliable friction hitch.

The purpose of a back-up is to apply braking force to brake strand, not take body weight. Unless you know you will need to ascend the line again, there are no advantaged to putting it above the device, and several disadvantages:

• More likely the friction hitch gets out of reach;
• More difficult to release the friction hitch if you weight it; and,
• Less able to control brake strand. (1-hand versus two hands).

Response to your bullet points. 

Tie it short

All it takes is to "break" the knot loose. Super easy.

That's what the back-up is for....
Get some tougher hands? It's not that hard.

Ted Pinson wrote: Yes.  People have had them get sucked into their devices and have lost control after inverting.

Anyways...the “brake hand” is whatever hand happens to be on the brake.  Stop overthinking it.  You’ll have two hands on the rope going down; one should be on the knot to keep it moving, one on the rope.

I'm trying to picture this...what happened first, rappeler inverted, or autoblock gets sucked into device?

How does the rope still move through the device if the autoblock cord is jammed in there..and how does inverting affect the autoblock?

One failure mode: If you rap with your rappel device on your belay loop and your back-up on a leg loop, becoming inverted prevents the back-up from applying braking forces because the relative position of the brake strand has now moved above the device. This allows the rope to continue to slide through the device, until the device contacts the back-up, there-by tending it until you reach the end of your rope.

If you rappel with an extension and have your back-up on your belay loop, you reduce the likelihood of this by a) increasing the distance between the rappel device and your back-up; and b) sharing common point of rotation if inverted, preventing an changes in back-up position that would allow more rope to slide through the rappel device.

Jim Titt wrote:

How to spell brake?

50%.... could be worse