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mec
Trad climber
Seattle, WA
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Topic Author's Original Post - Feb 9, 2009 - 09:23pm PT
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Ok, I have an A5/Northface Double Portaledge that I picked up about 10 years ago. I have not used it as much as I would like, but have done a handful of 2 day routes where I used the ledge. It does not work as well as I was expecting it to, and at first I thought I was just being a gumby and was doing something wrong. But now, I am not so sure.
When I setup the ledge, it tends to get kinked (it twists) really easily making it uncomfortable, and a bit weird to sleep on (as well as a little unsettling as one corner will be really low threatening to drop me off). I did some measurements and found out that the fabric bed pulls the middle together, and the middle is about an inch less wide than the ends of the bed (giving a gentle curve inward for the long sides of the frame. So, I am thinking that this might be why it twists easily.
I have bigger plans this year and want to be able to get some good solid use out of it without worrying.
Anyone have similar issues? any solutions? will BD take this in and fix it for me? I'd be up to try just about anything, I just do not want to have to buy a new ledge.
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Mr_T
Trad climber
Somewhere, CA
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Email BD. If it's metal fatigue, you're probably SOL. There's a reasonable chance they'd give you some kind of discount on a new ledge. If it's any consolation, I'm probably going to plunk down for a new ledge this year as well - 15 years of use on a home made...
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deuce4
climber
Hobart, Australia
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If you tension the bed tensioner straps when it is as flat as possible, you might find that the ledge really won't twist too much afterward. But if you tension the straps when it is twisted, then you will never be able to get the ledge to stay flat.
BTW the catenary cut in the middle is there to keep the fabric taut when the frame is naturally bowed by the weight. It wouldn't have anything to do with the twisting.
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Tom
Big Wall climber
San Luis Obispo CA
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Feb 10, 2009 - 12:13am PT
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I'm not smart enough to explain mathematically, here, why your portaledge wants to "taco" on you, but here goes:
If there is tension in the fabric membrane bed of your ledge while the frame is in a flat, planar configuration, the elastic energy stored in the taut fabric can be relaxed/released, by the frame twisting. This has to do with the fact that when twisted, the area bounded by the frame is smaller than when the frame is flat. In fact, the rectangular frame and membrane bed has an unstable equilibrium (a toggle, in effect) at the flat-point. If your ledge is good, with a taut bed, as soon as you step off it, it will taco on you.
This is pretty much true of any portaledge, unless the corners are rigid and don't allow rotation of the tubing. The first ledge I made had rigid corners, but they weren't strong enough to put up with the abuse of flagging it above the haul bag, and I was lucky to get to the top before it completely failed.
Just set the lengths of the straps correctly, aim yourself for the center of the fabric, and it will settle down nicely.
TIP: Set all the corner straps equal, but a bit shorter than you want. Leave the middle/side straps pretty slack. That way, when you get in and want to adjust it a bit, you're lowering a corner, not trying to raise one. The middle straps can be adjusted (standing off-center?) once the four corners are right.
EDIT: the catenary cut
This is exactly how to keep the bed fabric under tension. The frame is going to deflect, so John accomodated this with the subtle curve of the hem. In Australia (near the Barrier Reef) I saw many large architectural awnings/tarps, including at at the Cannes government building, that were designed the same way.
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Nefarius
Big Wall climber
Fresno
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Feb 10, 2009 - 12:42am PT
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Why would BD want to fix an A5/TNF ledge? I know they bought the stuff from Conrad, who bought it from TNF, who got it from Deuce... However, they have changed significantly since the design you have. While they might fix it, I'd doubt they'd do it for free. It's not their product. Not to mention, it doesn't sound like you have a ledge issue so much as you just need a little more experience with it maybe...
"I have bigger plans this year..." Sounds to me like you're about to solve your own problem. :)
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JLP
Social climber
The internet
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Feb 10, 2009 - 01:06am PT
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Sounds like you just need to adjust the straps. No big deal. You usually have to test and adjust the thing several times before it stays flat in a particular situation.
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'Pass the Pitons' Pete
Big Wall climber
like Ontario, Canada, eh?
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Feb 10, 2009 - 12:00pm PT
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It's probably ok - what you need to do is practise. Set your ledge up against your house or garage, or something with a flat wall, and get into it and bivi for a night or two. Hanging it from a tree doesn't work because you either end up twisting round in space, or else swinging round the convex trunk with only one [circular] point of contact.
Another possibility is that with age and lack of use, the fabric has become tight. I find my ledge much more friendly after I have slept in it for a night or two.
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Lambone
Ice climber
Ashland, Or
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Feb 10, 2009 - 12:06pm PT
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Every ledge twists like that (well, except for the old BD Skylounge).
What you need to do is saddle up, jump up on that sucker and straighten her out, then tighten the straps up. It's nearly impossible to get it straight without getting on it...even though it may feel like it's going to dump you.
Duece's advice is also really important. When i'm hanging at at belay I try to press the ledge flat against the wall, then tighten up the bed tensioners.
Good luck, Pete's right...just takes practice.
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Michael D
Big Wall climber
Napoli, Italy
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Feb 10, 2009 - 12:29pm PT
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Hi MEC,
Like Pete said, practice...a lot.
If you flatten out the ledge against the wall and yourself like a sandwich, lower it down, and step on the wall side tube with one foot, and the outside tube with the other foot, it'll stay put. I always have the straps extended a lot, than adjust before stepping in the middle of the fabric. Even my daughter can do this process now, but it took practice.
Good Luck, have fun :)
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