B Deleted_Beck Posted September 8, 2011 Share Posted September 8, 2011 (edited) howdy.. not sure where to put this, since there's apparently not a dedicated mountaineering sub-forum, oddly enough... for alpine mountaineering, with occasional soft belays on snow slopes but mostly for rapping... what are some thoughts on using dynamic cordelette? 6.5mm, 7mm, or 8mm... obviously the intent is to trim weight.. i can definitely trim a lot of weight. 6.5mm - 60m - 3.48lbs 7mm - 60m - 4.6lbs 8mm - 60m - 5.16lbs 10.3mm - 60m - 8.73lbs i did some screwing around with belay/rap/ascending devices... with 6mm, toothed ascenders seem to like to destroy the sheath.. 7mm not as much, and 8mm hardly at all. belay devices are obviously harder to control.. but it seems using a pinchier d-carabiner adds quite a bit of friction.. i was able to vertical rap with an ATC and a D-biner fairly controlled even with the 6mm. i haven't tried to catch a fall with it yet.. gonna have to try that tomorrow at le gym. it's not dry-treated.. so ending up with a soaking ass rope could defeat my purpose (in theory)... anybody ever tried nikwax/rope-proof on un-treated ropes? think that'd solve that issue? so... is this stupid? anyone else doing it? anything i'm missing? thanks Edited September 8, 2011 by bkb0000 Quote Link to comment Share on other sites More sharing options...
B Deleted_Beck Posted September 8, 2011 Author Share Posted September 8, 2011 i've decided to nix out the 6.5mm... incompatibility with devices just makes that one too extreme. i really like the sound of three and a half lbs, but i think the stupid outweighs the force on that one. so i'm left with 7mm @ 4.6lbs, and 8mm @ getting back up over 5lbs. anyone who might have done this before- how huge a difference have you found betweebn a 7mm and 8mm for devices? i see guys using 7.x twins with ATCs... but it seems like this is where the leap is (and probably why most of these devices say they only go down to 8mm). i should also add that a big part of the appeal is cost- 60m of 8mm dynamic cordelette is about half the price of any 60m 8mm climbing rope. being that it's my mountain line, its going to get absolutely trashed rapping around boulders and ice threads and pixie sticks and icy bollards and such, and i fully expect to replace it with frequency. Quote Link to comment Share on other sites More sharing options...
genepires Posted September 8, 2011 Share Posted September 8, 2011 you can increase the friction of any belay device by using more carabiners between the rope and your belay device. I have never heard of dynamic cordelette. The common stuff of the spool is static. If weight is the issue, then maybe it is wiser to evaluate the length of your rope needs instead of diameter so much. For typical mountain travel, a 60m is pretty long and unneeded. 40 to 50m maybe a better choice. Quote Link to comment Share on other sites More sharing options...
B Deleted_Beck Posted September 8, 2011 Author Share Posted September 8, 2011 you can increase the friction of any belay device by using more carabiners between the rope and your belay device. I have never heard of dynamic cordelette. The common stuff of the spool is static. If weight is the issue, then maybe it is wiser to evaluate the length of your rope needs instead of diameter so much. For typical mountain travel, a 60m is pretty long and unneeded. 40 to 50m maybe a better choice. its pretty rare, but it's there. climb max used to carry some, but i'm not aware of any other local shops- in fact, i tried OMC, MS, NA and even a couple REIs yesterday... none stock it. i'll be ordering direct from bluewater. as to length- you're right, for general mountain travel and belaying, 40m is ideal... but i want long raps. if the stuff was available in longer lengths, i'd probably still be looking at the 6.5.. Quote Link to comment Share on other sites More sharing options...
DPS Posted September 8, 2011 Share Posted September 8, 2011 What about a 30m, 8mm 'rando' rope and a 30m, 5 mm tech cord (http://promountainsports.com/index.php/climbing/ropes/tech-cord-5mm-60m.html) tag line? You get a dynamic climbing rope for when you need to rope up for glaciers or short technical sections while enjoying the weight savings of a lightweight tag line and the ability to do 30 meter raps. Quote Link to comment Share on other sites More sharing options...
Teh Phuzzy Posted September 8, 2011 Share Posted September 8, 2011 you can increase the friction of any belay device by using more carabiners between the rope and your belay device. Using a Bugette from DMM would probably help out with this as well as cutting some weight. Anyone ever use one of those things? Quote Link to comment Share on other sites More sharing options...
pcg Posted September 8, 2011 Share Posted September 8, 2011 I have a Bugette and I consider it too dangerous to use on an 8mm single strand Beal rope - really scary and you'd better have gloves on and a good grip and never get past low low gear. If you get moving you're gone. Reverso 3 provides more friction than a Bugette and an ATC Pro provides more still. All are still pretty scary if you are rapping in space, even if you clip two biners instead of one, which helps a little. If I am just rapping down a steep incline then I use an ATC Pro and pass the rope around behind my waist and brake with my hand and a glove, old school style. I wouldn't rap in space without an auto block. You can also stack a second rappel device using a cow's tail which helps quite a bit. The only thing I've found that gives a smooth controllable rappel with a single strand of 8mm is a monster Munter. Quote Link to comment Share on other sites More sharing options...
Teh Phuzzy Posted September 8, 2011 Share Posted September 8, 2011 The only thing I've found that gives a smooth controllable rappel with a single strand of 8mm is a monster Munter. found a good video for this (and a regular Munter Hitch) gonna have to give this some practice before taking it out Quote Link to comment Share on other sites More sharing options...
pcg Posted September 9, 2011 Share Posted September 9, 2011 Another option for a skinny rope is to use brake bars. These were commonly used by climbers for rapping many years ago and I think now they are mainly used by cavers. They provide a lot of friction, but if you want enough friction so that you don't have to wrap the rope around your waist, you need multiple brake bars and the weight starts to add up, as well as the complexity. I am still looking for a simpler solution. The monster munter is simple but it seems to me to be awfully hard on the rope. There is a lot of friction there and not much surface area to displace the heat since the rope is smaller diameter, so easy and slow is the way to go. Quote Link to comment Share on other sites More sharing options...
B Deleted_Beck Posted September 9, 2011 Author Share Posted September 9, 2011 (edited) brake racks are out of the question.. just too big, bulky, and heavy. Wild Country VC Pro 2... as if i need yet another belay device.. claims to be pretty pinchy for tiny rope.. anyone used one? there's pros and negs to each system.. but i gotta tell you, the dyno cord idea is sounding better and better. the stuff is strong.. and doubled up for belaying, i'd probably even be willing to take a decent lead fall on the stuff, from what i'm reading. 7mm dyno: 60m - 4.6lbs tensile strength: 10.4kN - single strand $90 all day long Mammut 7.5 twin: (cheapest dyno climbing rope i could find) 60m - 5.02lbs impact force: 9.9kN - double $144 - on sale, reg $180.00 whats the difference between impact strength and tensile strength? obviously they're using tensile on the cordelette because it's accessory cord, not dyno climbing rope.. Edited September 9, 2011 by bkb0000 Quote Link to comment Share on other sites More sharing options...
Buckaroo Posted September 9, 2011 Share Posted September 9, 2011 Your title is misleading, a cordelette is a 20' piece of cord for equalizing a belay anchor I wouldn't lead on anything as thin as you are talking unless it was fall rated, there's only so far you can push going light when it comes to lead ropes as far as devices, just add beaners either at the device clipin or on the side at the gear loop, or both. when you go real skinny for rapping you also have to go even smaller for prussik cord, like 4mm. also second DPS's suggestion Quote Link to comment Share on other sites More sharing options...
dfrost Posted September 9, 2011 Share Posted September 9, 2011 +1 to DPS's suggestion also--that's the most elegant solution to your problem. I've had the puckering experience of catching a lead fall on an 8.5 line. The cord was fine, but I'm hesitant to use a line that small again. Mammut makes a single-rated line at 8.9, which isn't much heavier. As for devices, I've rapped on doubled 6mm cord with a Munter--but it takes a bit to get used to, and the line wears very quickly. I think going with a real rope will offset the initial cost savings with it's durability. Quote Link to comment Share on other sites More sharing options...
DPS Posted September 9, 2011 Share Posted September 9, 2011 whats the difference between impact strength and tensile strength? Impact is how much energy is tranferred to the anchors when tested in a drop tower. Tensile strength is how much force it takes to break it when pulled apart. The fact the the 7mm cord does not have an impact force listed suggests to me that it is not intended for holding falls. Quote Link to comment Share on other sites More sharing options...
B Deleted_Beck Posted September 9, 2011 Author Share Posted September 9, 2011 whats the difference between impact strength and tensile strength? Impact is how much energy is tranferred to the anchors when tested in a drop tower. Tensile strength is how much force it takes to break it when pulled apart. The fact the the 7mm cord does not have an impact force listed suggests to me that it is not intended for holding falls. it's definitely not "intended" for holding falls (though that's really the only reason it exists).. i have no delusions about that. i've considered the rando/cord idea.. i'd have to do the 48m length, as 30m is just too short to be useful for anything, and really too short for crevasse protection as well. to avoid having a knot halfway down the rappel, i'd have to get 48m of cord, and even at 5mm, that'd put me back up to 5.5lbs. i'd get a sweet 48m rappel, but would also only get 48m of lead. if i just went with a straight up 7.5 or 8mm 60m climbing rope, i'd be at the same weight, AND i'd get the full 60m (i do realize we're talking about half rope) of lead. i appreciate the responses- this is sort of turning into one of those threads where it looks like the OP pretty much has his mind up despite everyone telling him he's an idiot.. but i am weighing all opinions. Quote Link to comment Share on other sites More sharing options...
B Deleted_Beck Posted September 9, 2011 Author Share Posted September 9, 2011 (edited) +1 to DPS's suggestion also--that's the most elegant solution to your problem. I've had the puckering experience of catching a lead fall on an 8.5 line. The cord was fine, but I'm hesitant to use a line that small again. Mammut makes a single-rated line at 8.9, which isn't much heavier. As for devices, I've rapped on doubled 6mm cord with a Munter--but it takes a bit to get used to, and the line wears very quickly. I think going with a real rope will offset the initial cost savings with it's durability. i've never tried a munter on double line- i think i didn't think you COULD double rap/belay with a munter on double lines... i'm gonna have to try that Edited September 9, 2011 by bkb0000 Quote Link to comment Share on other sites More sharing options...
DPS Posted September 9, 2011 Share Posted September 9, 2011 i'd have to do the 48m length, as 30m is just too short to be useful for anything, and really too short for crevasse protection as well. Not to sound rude, but where are you getting your information? I have made quite a few committing descents making 30 meter, and even 25 meter rappels. 30 meters is perfectly adequate for glaciers in the lower 48. Quote Link to comment Share on other sites More sharing options...
counterfeitfake Posted September 9, 2011 Share Posted September 9, 2011 this is sort of turning into one of those threads where it looks like the OP pretty much has his mind up despite everyone telling him he's an idiot.. but i am weighing all opinions. AHA! I knew you sounded familiar! You're that guy who asks weird questions for advice so he can argue. http://cascadeclimbers.com/forum/ubbthreads.php/topics/1003679/ http://cascadeclimbers.com/forum/ubbthreads.php/topics/1019030/ Quote Link to comment Share on other sites More sharing options...
B Deleted_Beck Posted September 9, 2011 Author Share Posted September 9, 2011 this is sort of turning into one of those threads where it looks like the OP pretty much has his mind up despite everyone telling him he's an idiot.. but i am weighing all opinions. AHA! I knew you sounded familiar! You're that guy who asks weird questions for advice so he can argue. http://cascadeclimbers.com/forum/ubbthreads.php/topics/1003679/ http://cascadeclimbers.com/forum/ubbthreads.php/topics/1019030/ and you must be the guy who seems to exist for the sole purpose of fucking up otherwise decent threads. thanks again, bra. --- consensus: there's better ways. noted. thanks for the replies, gentlemen. Quote Link to comment Share on other sites More sharing options...
yikes Posted September 9, 2011 Share Posted September 9, 2011 FWIW. I simul-rapped 20+ pitches of Infinite Bliss on a single strand of a fairly new PMI Verglass (8.1mm, ~5.5lbs per 60m). I used an ATC guide and two pearabiners. I wore gloves but I didn't need a death grip or anything unusual. I weigh ~175lbs and had no issues except some snarlage. YMMV. Quote Link to comment Share on other sites More sharing options...
Jake Kirk Posted October 7, 2011 Share Posted October 7, 2011 I also use the PMI verglass. Its very light and super slick. Its also dry treated and intended for alpine conditions. It is both twin and double rated. Some other company makes a 7.7 that weights the same amount per meter, I prefer the 8.1 for belaying and repelling. Cut it down to 50m and it weights 4.6 lbs... That's hard to beat, for the safety you get. If you pair it with a thin static rap cord you can do full length raps for little weight. jake Quote Link to comment Share on other sites More sharing options...
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