disappearing thread on tandem SRT

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disappearing thread on tandem SRT

Postby ek » Jul 17, 2010 3:43 pm

A new poster posted a new topic to the Caving General Discussion and Questions Forum, asking if you can have two people on a rope at the same time, and expressing specific interest in the practice of tandem rappelling. I was replying...and then the post disappeared (fortunately I backed up my post to a text file, so I didn't lose anything). I had figured the topic had been moved here...and then I saw it hadn't?

Does anybody know what happened?
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Re: disappearing thread on tandem SRT

Postby Stridergdm » Jul 17, 2010 5:03 pm

So you're saying the tandem SRT thread broke. Not a good sign. :tonguecheek:
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Re: disappearing thread on tandem SRT

Postby ek » Jul 17, 2010 5:21 pm

This goes to illustrate how, when tandem-discussing SRT, it is especially important to pad edgy conversation. :tonguecheek:
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Re: disappearing thread on tandem SRT

Postby neghafi » Jul 18, 2010 12:18 am

yea, it was my post and I lost it myself too! I'm looking for it but cannot find it.
actually I was not talking about tandem rappelling! if you had looked at picture it seems they are attached to the rope separately and not using a same device

Image

I'd cut a video clip from the video and asked my question (in Persian language :shhh: )
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Re: disappearing thread on tandem SRT

Postby ek » Jul 18, 2010 12:33 am

I don't know Persian, so I cannot read the text in the video, but since you're not asking about tandem rappelling, are you asking about tandem ascending?

(When I use the term "tandem rappelling" I mean two people separately attached to a rope and rappelling with separate devices. It is not a well-accepted practice, but some people do it. The top rappeller must rig his or her device with extremely low friction, which can cause big problems if the bottom rappeller reaches the ground when the top rappeller is high up. Tandem rappelling also often involves using a device in a manner for which it was not designed or tested.)

The bottom caver on the rope has both hands free, suggesting that they are tandem ascending, rather than tandem rappelling. But the rope packed into the bag suggests otherwise. If that's what that is...and maybe it's not. I can't really tell exactly what they're doing? Is there more context?

Perhaps they're being hauled out of the cave together, or something. Their motions seem similar neither to rappelling nor to ascending.

I wrote up a post about tandem climbing on a single rope. If that's what you're asking about, I'll go ahead and post it.
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Re: disappearing thread on tandem SRT

Postby neghafi » Jul 18, 2010 1:19 am

To me, it seems they are rappelling (not ascending).
I thought you meant tandem rappelling with a single device for 2 mates as in self-rescue. now I got what you meant. :kewl:
The top guy may use auto-locking knots (or Petzl's shunt) to secure himself about the situation you mentioned.

Being hauled out of the cave by a winch is a considerable option (but they forgot the camera man) and they don't need such a bulky case (in which contains rope). But I saw a handle (which I don't know what it is) for both cavers.

I also don't know what they are doing, but I thought there may be a secure way to make vertical movements faster (for example by a kind of tandem rappelling)
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Re: disappearing thread on tandem SRT

Postby NZcaver » Jul 18, 2010 1:29 am

Welcome to the forum. :waving:

Sorry to hear that your original post disappeared. It seems there was a glitch somewhere in the system.

It's difficult to tell from the short video clip, but it does appear to show 2 people and a large pack suspended from one rope. Or I guess it could be the upper person on rope, and the lower person and pack tethered to him/her. I think I can make out some type of devices on the rope directly above each person, but I can't be sure. Perhaps a winch/lower system is being used.

For what it's worth, the definition of tandem rappelling/abseiling I am most accustomed with involves 2 people, each side-by-side on their own ropes but tethered together for safety. Usually one will be an instructor, the other a student.
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Re: disappearing thread on tandem SRT

Postby gdstorrick » Jul 18, 2010 6:02 am

Post deleted.
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Re: disappearing thread on tandem SRT

Postby Phil Winkler » Jul 18, 2010 9:19 am

My bad. The original post seemed suspicious to me. Clearly I was mistaken. Sorry.
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Re: disappearing thread on tandem SRT

Postby NZcaver » Jul 18, 2010 10:09 am

gdstorrick wrote:To me, "tandem ascending" refers to the common practice of two people climbing the same rope at the same time, usually on long drops (to save time) and usually staying close together (for company and for falling object safety). I don't like to do it. If I'm the top climber and the bottom climber is not smooth, I experience nausea. The bottom climber is just a barf target, making that the less desirable position.

"Tandem rappelling" is not in my vocabulary. Neither are a lot of other things.

I concur with your definition of tandem ascending. Although not having done it myself, I cannot personally vouch for the barf factor. But it makes sense, so I have no reason to doubt you.

Interestingly, "tandem ascending/climbing" was never in my vocabulary when I began caving in New Zealand. We do have some big single-pitch pits (100m, 173m), but I guess the tandem climbing thing is an alien concept - at least to me. On the other hand, the term "tandem abseiling (rappelling)" is fairly common, although not usually in a traditional SRT caving context. But it's a useful teaching tool. We used it earlier this year when dropping Scouts off a natural bridge.
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Re: disappearing thread on tandem SRT

Postby Marduke » Jul 18, 2010 11:16 am

In the big TAG pits, tandem ascending is relatively common in pits of around 200ft or more. When you have a big group of people trying to cycled in and out of of a pit several times during a trip, it helps to get some people up faster. In general, two tandem climbers can save about 50% of the tie of two single climbers.

In my circle of friends, it's one of the things we practice. Couple points to remember is to put the more experienced climber on the top, since they have to deal with rope weight and most likely a change to a pigtail at the top to cross the lip (going from a weighted rope to a short unweighted rope). However, the bottom climber can also be the one to do this change to a second rope. Also, you NEVER put a frogger on the bottom, although most froggers love to be on top (rope weight helps them immensely). Systems with foot ascenders work better on top, and Mitchell systems suck on top.

For those familiar with caves in Huntsville, I've been in Hoopers Well (90') with 4 people on rope inside. Two tandem climbers on two ropes (one rigged on each side).

When it comes to tandem rappeling, I've heard of it on REALLY long drops, but never seen it. However, I have helped in practicing weighted rope rappels for those preparing to do rappel/climbs such as El Capitan, where you have 2650' of rope weight under you at the top.
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Re: disappearing thread on tandem SRT

Postby NZcaver » Jul 18, 2010 12:29 pm

Marduke wrote:Also, you NEVER put a frogger on the bottom, although most froggers love to be on top (rope weight helps them immensely).

I already knew most of what you said, but I'm wondering about this bit. I have caver friends who tandem climbed some big drops including Golondrinas and they were ALL frogging. They're experienced (obviously), and seemed to do fine. :shrug:
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Re: disappearing thread on tandem SRT

Postby Tim White » Jul 18, 2010 1:39 pm

The video clip appears (to me) to be one person rappeling with another and pack tethered below.

As for “tandem rappeling” I know folks that do this at Bridge Day and other events and locations more as a fun stunt than a real technique. The person on top often uses a 24” long (or longer) rappel rack to help reduce and control friction as ek stated in his post.
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Re: disappearing thread on tandem SRT

Postby gdstorrick » Jul 18, 2010 3:18 pm

Post deleted.
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Re: disappearing thread on tandem SRT

Postby Marduke » Jul 18, 2010 4:04 pm

NZcaver wrote:
Marduke wrote:Also, you NEVER put a frogger on the bottom, although most froggers love to be on top (rope weight helps them immensely).

I already knew most of what you said, but I'm wondering about this bit. I have caver friends who tandem climbed some big drops including Golondrinas and they were ALL frogging. They're experienced (obviously), and seemed to do fine. :shrug:


A frogger on bottom tends to put more bounce in the rope, which can be unsettling to the climber on top. When you put the frogger on top, the rope weight tends to make their motion much smoother, and is not really any more bouncy for the person on bottom than a ropewalker on top. This also translates to a little less jerk in the load on the rope/rigging.

Obviously, if you have an experienced climber with good technnique (as someone who would frog something like Golondrinas), they might not be very bouncy/jerky at all.

gdstorrick wrote:
Marduke wrote:... and Mitchell systems suck on top.


...puzzles me exceedingly :shrug: , unless it refers to the lip, but then you just jump to the tag line and Texas over. Piece of cake. :cupcake:


With a ropewalker, the foot ascender keeps you fairly upright. With a Mitchell, your feet tend to push further out, which means the weighted rope is riding right in your crotch all the way up, and is quite uncomfortable IMO.
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