Extending Rappel Device with Dyneema?

Larry S wrote: Another unmentioned advantage of this is technique is rappelling with a load - Extending the device lets you hang the load (heavy pack, Haulbag, injured partner) off carabiner at the device, which gives you the ability to move around unencumbered by the weight of the device. And when you arrive at the next anchor, it's easy to secure yourself and the load.

You don't need to extend the device to do this. I have rapped thousands of feet with a 30lb pack hanging off my belay loop.

polloloco wrote: For the extension, I see most people using a nylon 120cm (48") runner. What are your thoughts on a Dyneema 10mm wide 120cm runner? I think we've all seen/discussed the DMM knot on Dyneema videos. I was thinking that as a rappel extension, using Dyneema with an overhand in the middle should be of little concern. What do you guys think?

Like in many things, different nations worry about different things when it comes to climbing. In the UK and much of Europe it is impossible to even buy a nylon sling. Everyone just uses 8mm dyneema. Not saying which is best though.

Wow! Tons of great responses. I'm going to have to take some time to really digest all of this.

I'll try to clarify a few things based on some questions that came up.

1) I don't plan on anchoring off the extended like the Petzl site shows. I'll have two leashes of 7mm nylon with lockers to attach to the bolts while I clean. (Can save this for another thread...)
2) I do indeed plan on using a autoblock, and some research into it brought up the suggestion to extend the device.
3) If I were do extend, I'd have it as a dedicated set-up for it prior to the climb. IE, I won't be fiddling around at the top trying to rig it all up.

Regarding the topic of whether or not to even extend:
I'm going to have to really think about the pros and cons of all of this.
Pros:
Reduced risk of autoblock getting stuck
Better control of rope
Reduced risk of getting stuck up-side down
Cons:
More complexity
Your belay loop should be more reliable than any sort of extension you can make
Potential difficulty going over an edge.

Regarding the original question of Dyneema vs Nylon:
Seems like everyone's consensus is Dyneema in this application is acceptable assuming I'll be on dynamic rope and assuming I practice safe cleaning technique (maintain tension on personal anchor prior to going to rappel, smoothly transitioning to rappel, etc)
1) The knot in the middle, is OK because of what I mentioned above.
2) Take care to reduce rope friction on Dyneema since it is less heat resistant.

However, it is preferable to use nylon (except maybe in Europe ;)) if weight is not your concern.

I do like Marc H's comment on just using 2x 60cm nylon slings. I didn't think of that!

Awesome discussion. I couldn't cover all the comments right now, but will definitely do so and slowly weigh the pros and cons. Thanks!

mountainhick wrote:This has all been covered before on MP, but this is essentially the method I use for multi raps. Covers pretty much every aspect.

I wanted to point out that the overhand shown on this video is an overhand with a bight rather than the simple overhand shown in the "guide's choice" method. In the video method, the device is connected to 2 loops created by the overhand bight. Correct me if I'm wrong, but this satisfies the redundancy requirement for the rappel device side. In the "guide's choice", the 'biner saddles the knot if I understand the image correctly.

It seems like the "guide's choice" method, ie a simple overhand with a saddled biner, could give added stress on the knot. The video method that mountainhick linked seems - to me at least - as a more robust method if you wanted to do an extension. ... I think?

a few notes

- extending the rappel DOES change the pivot point, especially on lower angle raps where you walk down the slab

. With the pivot point higher relative to your body, it’s easier to stay upright when rappelling with a heavy pack.


climbing.com/skill/relaxed-…

- an extended rappel FORCES you to keep both hands below the device ... which is a good thing ... it allows a good breaking position for both hands

- an extended rappel allows the backup to be attached to the belay loop ... this can make it easier to manage and less likely to jam into the device

- since you are already using a sling or PAS to attach yourself to the rap anchors, it takes NO extra gear and is NOT realistically more complicated ... you just clip the device to the sling rather than the belay loop ... in fact with the backup friction knot being less crowded in yr groin, one can argue its simpler to inspect and manage

- an extended rappel is an important RESCUE skill to practice, whether you use a rescue spider, or a sling/PAS ... a tandem rap a likely way to get an incapacitated partner down, especially if you dont trust their judgement (due to injury) enough for them to be on their own for a lower

- an extended rappel is easily converted into an ascension rig if you have an autoblock device

from AAI

blog.alpineinstitute.com/20…

- an extended rappel is less likely to get clothing or gear caught in the device

- it allows stacking of rappels where both/all partners can double check their setups on the rope ... since rappel screw ups are a significant cause of accidents, this may be valuable especially with newer climbers

downsides?

- you need to know how to do it and PRACTICE it

- it doesnt work well with some assisted locking devices ... i have had poor results with the smart as it makes it harder to release IMO

- you have to make sure that the devices is extended less than an arm lengths away ... in case you need to re-ascend the rappel

- if you need to pass a knot its not the best as its harder to reach above the device to set the upper prussik

- youll have MP telling you its absolutely pointless on the intrawebs

folks use it all the time climbing, guides use it with their clients, petzl recommends it in their literature ...

whether you use it or not is up to you ... but it works just fine... its a proven technique thats been used over and over again

i used to use it alot when i rapped on a ATC guide ... now with a smart i go off the belay loop as harder to release it when extended

;)

I've been using this setup with a loop chain PAS for about a year now and don't see myself going back to the "standard" method, especially now that Bearbreeder has shared the rope ascension trick.

I find it quick and easy to set up, and much prefer having the auto block on my belay loop instead of the leg loop. I know some here disdain "extra" equipment and "extra" steps, but when I find equipment or procedures that add significant safety or functionality, I'll tolerate a little complication or added weight. In this situation, there is little of either. Once you have practised the extended rappel, the extra time needed to set it up is negligible or non-existent.

The PAS I use (Bluewater Titan) is lightweight and unobtrusive and for this application I have no qualms about it being dyneema rather than nylon.

On multiple long hanging rappels have one climber clip in with a double length runner and one clip in with a single length. This keeps you out of each others lap.

Can a hot rappel device melt your dyneema rappel extension? No, probably not, but nylon has a much higher melting point.

Source: blackdiamondequipment.com/e…