Rappel Racks

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Rappel Racks

Postby Vertigo » Nov 1, 2006 10:54 am

Is it a bad thing to always use 6 bars? Never 5 or 4? :question:
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Postby chh » Nov 1, 2006 11:23 am

Bad to use 6 all the time? Nope. It can be frustrating sometimes though, depending on your weight. Dropping a bar is something you want to do correctly, and caution should certainly be used. You can inadvertantly rid yourself of the friction from 2 bars by only taking one off depening on the orientation of your rack. i.e. does your rack go right on the maillon or on a carabiner and then on the maillon. That also presumes the use of a normal style caving harness and an in-line rack. You could be using a rack with a 90 degree turn in the eye, or a U rack right on the maillon. I don't know what you use. Reducing friction will usually involve switching hands to maintain the right reduction in friction. Without switching hands you loose more than one bar's friction and as much as 2 bars.

But maybe that's not what you're asking? Maybe you routinely use 4 or 5 and are wondering why it would be bad to use 6 all the time? Though, in this case I don't see why you wouldn't be able to anticipate the answer to the question in the first place. Moral of the story is BE CAREFUL when dropping bars.
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Postby Vertigo » Nov 1, 2006 11:46 am

I use 6 bars all the time and have no problems with getting going. The weight of the rope seems to be no problem for me and I don't anticipate any problems on a 1000ft. rope.
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Postby Tim White » Nov 1, 2006 11:55 am

caver86 wrote:I use 6 bars all the time and have no problems with getting going. The weight of the rope seems to be no problem for me and I don't anticipate any problems on a 1000ft. rope.


Much still to learn Grasshopper. :-)

1,000 ft. of 11mm rope is 50+ pounds. Most likely you’d be feeding for the first few hundred feet with all 6 bars engaged on a standard rack, smply due to the added friction caused by the weight of the rope.
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Postby chh » Nov 1, 2006 12:06 pm

fair enough. Whenever I've had anywhere near that amount of rope under me I've had to drop a bar to get started. Anything over 500 feet of rope and with six bars I might as well be locked off. I'm not the world's heaviest individual though. And the 6th comes back on when I feel it's necessary.
As to the original question, what are your concerns with using six all the time? Heat dispersal? Wear? There might be a little difference in the way things work out with, say, 5 bars but I can't imagine they would be of an appreciable difference in the short run. I'd say if you can move on six. Use six. :grin:
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Postby Vertigo » Nov 1, 2006 1:41 pm

I already know that I would have to feed the rope. I like it like that. That's how I like to descend. I don't like to go fast. Isn't it safer to feed the rope at the top anyways? Does this put to much wear and tear on the rope and rack? Am I trying to be too safe?
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Postby mgmills » Nov 1, 2006 2:15 pm

caver86 wrote:I already know that I would have to feed the rope. I like it like that. That's how I like to descend. I don't like to go fast. Isn't it safer to feed the rope at the top anyways? Does this put to much wear and tear on the rope and rack? Am I trying to be too safe?


IMHO it is never safer to feed rope. Feeding rope can cause a bar to become dislodged.

If you cannot descend without feeding you need to work on your technique so that you can stop feeding the rope. I rarely rappel with six bars. I don't rappel fast. I too like to go slow. With a standard rack I have been able to maintain good control with 5 bars. Exceptions are very flexible ropes and very wet ropes. That said, I usually put six bars on to "test" the rope but 99% of the time I take off the sixth bar.

The way I was taught is the key to rack control is to get the correct spacing of the bars. Once you are rapelling the control should come mostly from your bottom two bars. When rapelling always keep you hand on those bars ready to tighten them up if needed.
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Sounds good to me

Postby Vertigo » Nov 1, 2006 2:30 pm

I have been thinking about this lately which is why I posted. Feeding the rope is really just taking the rope's weight off of the bars so it can move freely while keeping tension on the bottom bar so it does not move. If you mess up, you really could pop a bar off. :panic: Also, I don't think I can get as smooth of a rappel using that technique. I do think a smooth rappel is key. :caver:
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Postby chh » Nov 1, 2006 2:53 pm

If you cannot descend without feeding you need to work on your technique so that you can stop feeding the rope. I rarely rappel with six bars.


The way I was taught is the key to rack control is to get the correct spacing of the bars. Once you are rapelling the control should come mostly from your bottom two bars. When rapelling always keep you hand on those bars ready to tighten them up if needed.


:exactly:
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Postby Scott McCrea » Nov 1, 2006 3:58 pm

Feed rope only in moderation. Momentum is your friend while rappelling. As long as you have some momentum built up, it's pretty easy to maintain a smooth rappel. Sometimes, you need to feed a few feet of rope when starting to gain some momentum. But moving all the way down a rope by feeding rope is dangerous and is not rappelling.
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Re: Sounds good to me

Postby Steven Kesler » Nov 1, 2006 4:17 pm

caver86 wrote:Feeding the rope is really just taking the rope's weight off of the bars so it can move freely while keeping tension on the bottom bar so it does not move.


That's close ;-). It is actually possible to have more friction than is accountable due to rope weight. Imagine a rack with 10 bars on it. If all 10 bars were threaded and there was not much spacing between the bars, you would probably not move down rope even if you had 2 ft. of rope below you.

The friction provided by a rack has a lot more to due with the material the bars are made from (for example, aluminum bars tend to have greater friction than stainless steel), the spacing of the bars (five bars on a shorter rack offer greater friction than five bars spaced out on a longer rack), the type of rope (slick, new 9mm static rope is much faster that an old, stiff, fuzzy 11 mm), and the weight of the person on rope (a heavier person tends to be faster while a lighter person slower - all other things equal), as well as whether the rope is wet or dry, clean or muddy, or freezing.

When approaching a rappel I recommend the person take a look at the surroundings to determine the "speed" of the rope under the prevailing conditions - something you will only really appreciate with experience. The advantage of a rack over some other descending devices is you can fairly easily change the amount of friction to control your descent. For a novice vertical person I recommend to always begin with all the bars engaged - if that setup proves to provide too much friction to move you can always carefully take a bar off until you can move.

I find that when I have the right amount of friction I can actually provide fine tuning adjustments for my speed with just my hand placement - perhaps a slightly tighter grip with my control hand or just moving my control hand to below my thigh so the rope rubs against my leg as I rappel.

It is possible to "feed" the rope through your rappel device. However, there are a couple of issues which come to mind regarding this practice. First of all, feeding the rope through the rappel device can be very tiring. If you have to feed the rope for more than a few meters it can tire you out fast. Descending a rope should require only minimal effort from the rappeller, and you should conserve your energy for any maneuvers you might need to perform such as crossing a knot, deviation, or rebelay.

caver86 wrote:If you mess up, you really could pop a bar off. :panic: Also, I don't think I can get as smooth of a rappel using that technique. I do think a smooth rappel is key. :caver:


Also, when feeding a rope through your descender, particularly on a rack, there is a real possibility that if you are not carefull and pay attention to your rack, a bar may pop off the rack, dramatically reducing the amount of friction. One way to lesson the risk of a bar popping off is to grasp the lower bars with your left hand while feeding the rope with your right (control hand).

Furthurmore, I find it difficult to descend smoothly when feeding the rope. When I have to feed the rope through my descender I notice my descent tends to become bouncy.

Whenever you are on rope you should really strive to be as smooth and fluid in your motions as possible. A jerky motion - either descending or ascending - transmits small shockloads up the rope to the anchors. I see no reason to test the anchors in this way. If you find yourself having to feed rope through your descender, decrease your friction if possible until you begin to descend - slowly - at a controllable pace. You should be constantly monitoring your descent anyway - looking to see where the rope goes, looking to see if there are any obstacle you will encounter such as a knot, redirect, or rebelay, or unexpected not. In this way if you feel your descend is faster than you feel comfortable with you may always add friction to the system.

The original question was whether six bars was safe for a rack. The short answer is: it depends - too many bars may result in too much friction and having to feed the rope which can be very tiring and can lead to a jerky motion while descending. If this is the end result, there is too much friction and it would probably be more efficient to drop a bar.

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Postby caver79 » Nov 1, 2006 4:52 pm

How about purchasing a hyper bar for your rack. I removed my sixth bar about 7 years ago to allow for better spacing and control. If I ever need the extra friction then I pull the rope over the hyper bar. Of course, this does not work well for drops of more than 500 feet. For longer drops, I use spacers between bars one and two, and two and three, and I add my sixth bar back on for times when the rack heats up.
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Postby Steven Kesler » Nov 1, 2006 5:06 pm

caver79 wrote:How about purchasing a hyper bar for your rack. I removed my sixth bar about 7 years ago to allow for better spacing and control. If I ever need the extra friction then I pull the rope over the hyper bar. Of course, this does not work well for drops of more than 500 feet. For longer drops, I use spacers between bars one and two, and two and three, and I add my sixth bar back on for times when the rack heats up.


I have found hyper bars to be of great use. I use a BMS Micro Rack with dual hyperbars. The racks are compact - something I recommend no matter what ascending system you use. Hyperbars are a quick way to increase the friction and offer a quick and easy way to lock off the rack.

I have seen spacer bars used on racks. Typically I have only seen them on racks used by heavier people. I have never used spacers (but, that may be because I haven't tried them either :-).

You mention hyper bars do not work well for longer drops. I disagree. because hyper bars are so simple to use (you just wrap the rope over the bar to increase friction) they offer an advantage over some types of racks when adding or decreasing bars. I have found on longer drops, when I feel my speed increasing beyond where I feel comfortable, I need only to lift the rope and wind it over the bars - very conforting.

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Postby Vertigo » Nov 1, 2006 5:39 pm

So maybe I could drop to 4 bars and my hyperbar? :question:
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Postby Steven Kesler » Nov 1, 2006 6:24 pm

caver86 wrote:So maybe I could drop to 4 bars and my hyperbar? :question:


I can't tell you what the least you need to use to rappel safely is because there are so many factors involved. The bottom line is you need enough friction to have a controlled descent - the operative word here is CONTROLLED. The techniques you use for descent are things you will find out through experience.

I always caution folks to start out with more friction than you think you may need (assuming your device allows you to easily change the configuration to lesson friction if need be) - racks allow you to simply alter the friction to less if needed.

Generally, more friction can usually be added to whatever descending device you use; However, some descending devices - figure 8's and most tube descenders, even bobbins for that matter, do not easily allow you to decrease friction once on rope. That is why I recommend you look at the specific conditions of the pitch, rope, gear you have with you, and descender, and rig the descender accordingly. Again, this is something you will learn through experience.

There are ways to start with more friction even if you are using another device such as a bobbin, by using additional friction carabiners attached to your harness mallion or leg loop - these can easily be taken out of the system if you find you have too much friction.

So, how do you gain experience? Hopefully you are able to find a competant person to go caving with and get a chance to cave under a variety of conditions - long drops, muddy ropes, wet ropes, etc. Ask the competent person how they rig their descender - you may learn something from it :-)

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