Rack alternative for long drops?

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Rack alternative for long drops?

Postby dutchcontractor » Mar 7, 2012 8:29 pm

This seems to be a tricky question, but is there a alternative device for rappelling long drops? (As in 400+ feet)

My buddies and I have had this discussion a few times but never really got a sure answer. We've looked at professional devices, SRTE for example and other devices some upward of $500. The companies that were contacted, either had no idea of the limitations of their device (probably an employee issue) or were not willing to say; "Sure it will work for x amount of feet".
Looks like the scarab may be an alternative? Seems to work in their tests but that's a very slow rappel, also makes me wonder if you'll be pulling yourself down at the top of a big drop due to rope weight.

Not that I am personally looking for an alternative, I am perfectly happy and comfortable with my 18" rack, just seeing what other peoples experiences are.
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Re: Rack alternative for long drops?

Postby Scott McCrea » Mar 7, 2012 9:31 pm

I read once about some cavers that invented a rappel device that squeezed the rope. Two plates with a screw to tighten them together... or something like that. Tighter=slower and vice-versa. It didn't work, IIRC. Perhaps someone else, Gary Storrick?, will know more. Heck, he probably has the thing in his collection.

The rack is the only device I know of that is capable of safely managing long drops.
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Re: Rack alternative for long drops?

Postby NZcaver » Mar 8, 2012 3:01 am

dutchcontractor wrote:This seems to be a tricky question, but is there a alternative device for rappelling long drops? (As in 400+ feet)

In this caver-authored article on cavediggers.com, the SRTE Stop you mentioned is implied to be useful on drops of at least 600 feet. I admit I do own one of these :shhh: but I haven't had the opportunity to use it on any long drop rappels.

Scott McCrea wrote:I read once about some cavers that invented a rappel device that squeezed the rope. Two plates with a screw to tighten them together... or something like that. Tighter=slower and vice-versa. It didn't work, IIRC.

Are you thinking of the Troll Allp? If so, these actually work rather well (I own several variants). But again, I have not had the opportunity to use one of these on any really long drops.
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Re: Rack alternative for long drops?

Postby PeterFJohnson » Mar 8, 2012 12:30 pm

I have wondered before about where people draw the line for non-rack devices. As the OP mentioned it is tricky because it is dependent on rope diameter, condition of rope, water exposure, etc. But I do wonder if the limit many cavers place on non-rack devices isn't a bit conservative. I would be interested to hear the opinions of anyone who has used non-rack devices on longer drops.

My own experience:

Petzl Simple: I have used a simple up to 300' without the slightest issue. I won't speculate on what the upper limit for a simple is, but it certainly is more than 300', especially on larger diameter ropes.

Petzl Rig: I have used a petzl rig to descend 350' + drops many times all without the slightest issue. Petzl cautions not using the device above 200m with a rescue load - i.e. during a pick off. But I see no reason to believe that the device couldn't be used well past 400+ feet - well below Petzl's 200m. One issue would be whether rope weight would lock the device as it does with a stop. Of course this isn't really a descender that was designed for or is well suited to caving, and it is stamped only for 11mm rope.

The "literature":

Alpine Caving Techniques states that you should use a rack "for those rare rappels over 200m without a rebelay"(pg. 145 in my edition). That would be 656 feet. That seems a bit high to me, but leaves a lot of room between 656 feet and the 400 feet you stated.

Thoughts? I am imagine this is going to bring out some die hard rack users. What is everyone's experience with this? I have some thoughts on the two major factors that would come into play(Friction variation due to rope weight, and overheating the device), but I am curious what others know.
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Re: Rack alternative for long drops?

Postby Caver John » Mar 8, 2012 1:09 pm

dutchcontractor wrote:This seems to be a tricky question, but is there a alternative device for rappelling long drops?
Looks like the scarab may be an alternative? Seems to work in their tests but that's a very slow rappel, also makes me wonder if you'll be pulling yourself down at the top of a big drop due to rope weight.

Not that I am personally looking for an alternative, I am perfectly happy and comfortable with my 18" rack, just seeing what other peoples experiences are.



The scarab intrigues me. I'd like to try one.
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Re: Rack alternative for long drops?

Postby ian mckenzie » Mar 8, 2012 2:53 pm

Scott McCrea wrote:I read once about some cavers that invented a rappel device that squeezed the rope. Two plates with a screw to tighten them together... or something like that. Tighter=slower and vice-versa. It didn't work, IIRC.


You may be thinking of Canadian caver Kirk McGregor who made one for his rappel of Mt. Thor in 1983. it did work; there is a brief description in The Canadian Caver Vol 15 no 2. The US cavers on that trip used racks that were twice the normal length.
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Re: Rack alternative for long drops?

Postby LukeM » Mar 8, 2012 3:35 pm

Read "THE BATTLE OF THE GOUFFRE D'APHANICE" from the link below. In this case Petzl Bobbins (Simples?) were used for an 820ft portion of an 1100ft drop, but not without a bunch of hassle. Really I'm beginning to think the upper limit for non-rack devices is quite high and it all depends on the amount of hassle you're willing to put up with. Playing with weighted ropes while using your particular device and body weight is probably the best way to get real answers.

http://www.scavalon.be/avalonuk/av04.htm

I had no issue using a micro rack in Surprise Pit and have no doubt that it would serve me well in a pit that is quite a bit deeper. Granted, that's not a rack alternative but it's a lot smaller than a full rack and I think many people assume they suck for longer drops. I think the short framed version (I used the long frame) would give less flexibility but some people are forced to use that because of their size.
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Re: Rack alternative for long drops?

Postby chh » Mar 8, 2012 7:57 pm

The good thing about Simples is that after you log a few miles of rope they get easier to use on longer drops because you wear a groove in the bollards that is the size of the rope that you most often use. If you are mostly on 11mm (like me) this groove is bigger than the one that comes on the bollard to begin with. Just this past weekend on some pits I was thinking to myself "Dang, self, I really needed that braking carabiner on the bottom there!" Guess it's time to flip them. :laughing:

I'll also chime in and say that 400 foot drops on 11mm static rope, no problem for the Simple. I've not done anything deeper than that with it, but I would.

And as far as people complaining about what a hassle it is to rappell 800 feet with this or that device, I say "meh". I've always found the climb out of anything even approaching that depth WAY more of a hassle.
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Re: Rack alternative for long drops?

Postby LukeM » Mar 8, 2012 8:02 pm

chh wrote:And as far as people complaining about what a hassle it is to rappell 800 feet with this or that device, I say "meh". I've always found the climb out of anything even approaching that depth WAY more of a hassle.


True, but you may not be so keen on wearing your arms out if you know you have 1500 ft of climbing and derigging to do to get out of the cave! :grin:
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Re: Rack alternative for long drops?

Postby dutchcontractor » Mar 8, 2012 9:15 pm

A buddy of mine was thinking about using a Petzl Rig in Fantastic (586'). Has anyone tried this before? I told him to better have someone else try it first :tonguecheek: It's basically a Grigri on steroids, but I know they get hot quickly, especially if you use the brake handle instead of your brake hand.
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Re: Rack alternative for long drops?

Postby gdstorrick » Mar 9, 2012 5:03 am

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Re: Rack alternative for long drops?

Postby gdstorrick » Mar 9, 2012 5:03 am

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Re: Rack alternative for long drops?

Postby NSS8921 » Mar 9, 2012 12:27 pm

[quote="I had no issue using a micro rack in Surprise Pit and have no doubt that it would serve me well in a pit that is quite a bit deeper. Granted, that's not a rack alternative but it's a lot smaller than a full rack and I think many people assume they suck for longer drops. I think the short framed version (I used the long frame) would give less flexibility but some people are forced to use that because of their size.[/quote]

Luke, I prefer to use a long frame micro rack for drops 160' and shorter, but it gets quite hot on dry ropes. I would go much deeper on wet ropes, just haven't yet. how hot did your your micro rack get in Surprise and how wet was the rope?
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Re: Rack alternative for long drops?

Postby LukeM » Mar 9, 2012 3:00 pm

The rope was dry and the rack did get hot, but not enough to damage the rope. I'd say I descended at a normal speed, maybe stopping once or twice to admire the glory of that pit. For the record I weighed about 155-160 lbs at the time and getting started down the rope wasn't too bad, but it was skinnier than 11mm.
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Re: Rack alternative for long drops?

Postby PeterFJohnson » Mar 9, 2012 5:23 pm

LukeM wrote:Read "THE BATTLE OF THE GOUFFRE D'APHANICE" from the link below. In this case Petzl Bobbins (Simples?) were used for an 820ft portion of an 1100ft drop, but not without a bunch of hassle.


Great story. Perhaps a conclusion I would draw from it is that a Simple cannot be used on a 820 foot drop - at least under those conditions. If you have to pull the rope up with an ascender to feed it I think your descender has failed...

chh wrote:The good thing about Simples is that after you log a few miles of rope they get easier to use on longer drops because you wear a groove in the bollards that is the size of the rope that you most often use... "Dang, self, I really needed that braking carabiner on the bottom there!" Guess it's time to flip them.


I have had this problem as well. It is especially true if you wear the bobbins down using 11mm rope and then do a drop on something with a smaller diameter. I would be hesitant to do long drops on a really worn Simple for this reason. As the friction changes towards the bottom you might find yourself going faster than you would like in a way you can't predict.

gdstorrick wrote:There are several issues on long drops.

(2) heat dissipation:


Does anyone know what the relationship between length of drop and device temperature? Is it linear? Also, does anyone have any instances of a device critically damaging a rope due to temperature?

gdstorrick wrote:(4) How much do you weigh? If you are tall and overweight like me (200 lb), you might notice that many of the people who like Simples are shorter and lighter (150#). Some devices work better for smaller people.

In my mind, the question should not be "how long a drop can I use a(n) _______ on?" A better question is, "What is the best device choice for this drop?"


As for "what is the best device choice for this drop", I don't see how you can decide that without knowing the capabilities of each device. One of the capabilities you need to know is how it performs at varying heights. But there are others - things like whether or not you want to carry a full size rack on a 24 hour trip. How that device performs on other drops you might be doing on that trip. How the device performs in rebelays. Or whether you already own a suitable device. etc.etc.

I don't think I want to limit myself to only using the one single "best" device on any drop, as circumstances change. I would rather have options. I do however want to limit myself to what is safe to use and to do that I need as much good information as I can get about every device. (For what it is worth, your site is a great resource in this regard Gary).
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