Draagun1 Posted September 14, 2008 Share Posted September 14, 2008 Wanted to know if this was safe.Fairly new to trad and building my rack still. I have Camalots and just bought some Helium 20cm quickdraws since the price was cheaper than individual binerers.Since now I have the extra 10mm wide dyneema dogbones could I girth hitch the 20cm long dogbones to the short loop on my Camalots and rack with the helium, this way I could use short and add a runner or extend full length =12.5" thumb loop to rope end of biner. My buddy said the 10mm dyneema would cut through the Camalot loop when girth hitched.Can I do this safely or is this a dumb idea. Quote Link to comment Share on other sites More sharing options...
goatboy Posted September 14, 2008 Share Posted September 14, 2008 Creative idea. Â Can you do it and likely get away with it for awhile, or for a long while? Sure. Â Is it the best, and preferred, way to use that gear? Is it the way that sets you up for success while minimizing unnecessary risk (webbing abrading on other webbing, using an inherently weaker knot)? Â You ask if you can do it safely or is it a dumb idea. I say the answer to both questions is no. It's not dumb, but nor is it safe. Quote Link to comment Share on other sites More sharing options...
Sol Posted September 14, 2008 Share Posted September 14, 2008 don't do it. Quote Link to comment Share on other sites More sharing options...
Draagun1 Posted September 14, 2008 Author Share Posted September 14, 2008 It looked pretty sweet when I thought of it and set it up but the main issue is safety.I'll think of something else to do with the dogbones I'm sure. Hey,just noticed I got upgraded to Journeyman on this post Quote Link to comment Share on other sites More sharing options...
Buckaroo Posted September 14, 2008 Share Posted September 14, 2008 Knots can be stress raisers. Â I don't know for sure but don't think dyneema will cut through nylon under normal loads. Â You could probably get away with this because of the safety margins of these runners but you would want to really pay attention to the average safety lifespan of synthetic products which is about 5 years. Because adding the stress raiser knot to age fatigue may come closer to breakage. Â an alternative is just to rack a few 10cm slings with one beaner, then just clip to the racking beaner on the cam when you need more length. Quote Link to comment Share on other sites More sharing options...
Jens Posted September 14, 2008 Share Posted September 14, 2008 Great question. I started doing something similar a few years ago on some of my cams and have wondered the same question. I've taken some falls on them in the configuration and everything looks ok. Â Perhaps someone who works in the industry will have some insight? Quote Link to comment Share on other sites More sharing options...
hafilax Posted September 14, 2008 Share Posted September 14, 2008 I don't think it's a good idea. Dyneema can slice through nylon at pretty moderate loads. It's a really low stretch material and when it is tied all of the force is taken up by the strands with the longest path length. This can create incredible pressures that will cut into whatever it's tied to. There was a recent incident where a dyneema sling cut through a nylon sling in a top rope setup IIRC. I think is was a route cleaning situation. Â This is why BD didn't go with extendable slings on the C4s. They found that the double wrap destroyed the plastic coating on the loops at forces common in big falls (again IIRC). Â I also think that it will clutter things up more than just carrying a couple of quickdraws. How often do you place every cam on your rack and extend them all? I'd rather carry a couple of slings over the shoulder with a single biner for a quick and easy minimal cam extender. Quote Link to comment Share on other sites More sharing options...
Jens Posted September 14, 2008 Share Posted September 14, 2008 Good discussion. Â I've had mt. tools double spectra wraps on my cams for at least 10 years now and taken some monster falls on them. It would be curious to hear from some of the BD folks. Â Extending all cams by using a quickdraw (2 biners) is far to much weight for harder routes. Quote Link to comment Share on other sites More sharing options...
hemp22 Posted September 15, 2008 Share Posted September 15, 2008 Here's one industry guy's write-up on the topic: BD QC w/ KP: extending cams BD QC w/ KP: sling on sling action  Also, if I remember correctly, the final Mammut investigation into the "cut" top-rope/cleaning anchor was that the break was consistent with being cut with a sharp object - NOT with being worn through by another sling. Quote Link to comment Share on other sites More sharing options...
Jens Posted September 15, 2008 Share Posted September 15, 2008 Thanks for link. Â By my math from the link, I'm OK to keep doing what I've been doing safely. Quote Link to comment Share on other sites More sharing options...
pindude Posted September 15, 2008 Share Posted September 15, 2008 When dogbones first came out, I understood they were meant to be used as draws to clip bolts only. That's how I try to use my mine. For trad routes and clipping to trad pro, active or passive, I always clip using a biner, and use regular non-stiff, flexible slings. Â Using a biner to clip to the piece makes it easier and quicker to place on lead, clean and rack for the second, and hand off at the belay if needed and re-rack/organize gear. Â Using a regular, flexible sling--vs. a stiff dogbone--allows more flexibility and movement, including side-to-side movement, under the stresses and force of a fall that will better allow the rope-end biner to move in the best possible position as the rope runs through it. Â Remember Goran's fall on Air Guitar, when he was using dogbone draws with trad pro. His top piece pulled out or was knocked out, and the second piece likely would have caught him but the rope-end biner broke. This second piece was an older-style U-shaped #2 Camalot that had a dogbone draw clipped to it. It was thought that the stiffness of the dogbone-draw could have contributed to the rope-end biner getting stuck in the crack, resulting in it breaking. Â Girthing or slinging a Camalot directly with a dogbone, without a biner, affords even less flexibility for the rope-end biner to move around. Â Â Â Quote Link to comment Share on other sites More sharing options...
Kletterhund Posted September 16, 2008 Share Posted September 16, 2008 Hmmm, errrrr, looked to me like the math within those links (good info there ...) showed all sling to sling, especially of very dissimilar diameters, attachments to be weaker that those made with a connecting carabiner ... Could be the RPN ... Quote Link to comment Share on other sites More sharing options...
Draagun1 Posted September 16, 2008 Author Share Posted September 16, 2008 I enjoyed the links also.Very enlightening.Thanks Hemp22. But what is the "RPN" Kletterhund? Quote Link to comment Share on other sites More sharing options...
RuMR Posted September 16, 2008 Share Posted September 16, 2008 (edited) Good discussion. I've had mt. tools double spectra wraps on my cams for at least 10 years now and taken some monster falls on them. It would be curious to hear from some of the BD folks. Extending all cams by using a quickdraw (2 biners) is far to much weight for harder routes. oh bullshit jens... "I fell off cuz my gear was too heavy"...I personally only fall off because I'm too fat and heavy... Edited September 16, 2008 by RuMR Quote Link to comment Share on other sites More sharing options...
eldiente Posted September 16, 2008 Share Posted September 16, 2008 Yeah this sounds like a bade idea. Not every cam needs to be extended, and taking a big whip onto webbing that was tied onto other webbing would make me nervous   Quote Link to comment Share on other sites More sharing options...
mkporwit Posted September 16, 2008 Share Posted September 16, 2008 But what is the "RPN" Kletterhund? RPN usually stands for Reverse Polish Notation. It's a way to do mathematical calculations that maps well onto how most computers operate. Quote Link to comment Share on other sites More sharing options...
Alpinfox Posted September 16, 2008 Share Posted September 16, 2008 I believe there is some general rule of thumb about hard/soft not hard/hard or soft/soft. Â That is, biners (hard) shouldn't be clipped to other biners (hard) directly, nor should slings (soft) be connected directly to other slings (soft). When one biner is connected directly to another biner (or a bolt hanger for that matter), the amt of surface area in contact is extremely small resulting in very high local forces which can damage the metal. When a sling is connected directly to another sling, the bend radius is very small again resulting in high local forces which could cause failure if the material was old/weakened etc. Â The combination of hard/soft, a sling connected to a biner, allows maximal surface area contact and therefore lowest peak forces. Â I'm not an engineer, but the above makes sense to me. Quote Link to comment Share on other sites More sharing options...
RuMR Posted September 16, 2008 Share Posted September 16, 2008 (edited) uhhh yeah...i constantly see bolt hangers shearing biners  I also see swaged wires on nuts cutting biners all the time...  ...actually, i think a girth hitch works like a knot in that some of the base material is compromised by the knot...i don't have the numbers, but a figure 8 fails a rope at something like 90% (again, i'm pulling out of my ass here)...  there is something to be said for the relative melting issues (kevlar/dyneema/nylon) and from absolute melting issues (ie rope running over sling)...  My personal opinion...in the middle of a route with a fair bit of gear in, a relatively low fall factor, and a bunch of secondary pieces below the top piece, i wouldn't give it a second thought...right off the anchor, i'd be a little more "judicious"...  absolute rules/dogma is for the brainless...  Carry on... Edited September 16, 2008 by RuMR Quote Link to comment Share on other sites More sharing options...
RuMR Posted September 16, 2008 Share Posted September 16, 2008 where is catturdeat with a discussion like this?? WTF... Quote Link to comment Share on other sites More sharing options...
Alpinfox Posted September 16, 2008 Share Posted September 16, 2008 uhhh yeah...i constantly see bolt hangers shearing biners  I didn't say "sheared" numbnutz, I said damaged. I've got plenty of quickdraws with bolt-side biners with gouges and deep scratches in them. You don't?    I also see swaged wires on nuts cutting biners all the time...  Wires are flexible and therefore count as pseudosoft. Like your brain.   Quote Link to comment Share on other sites More sharing options...
RuMR Posted September 16, 2008 Share Posted September 16, 2008 my biners are fine, some local damage is no big deal, my guess, they'll still rate out 95% of a new one...i just don't run ropes through that side... Â wires can cut like knives...your point was wrong...you absolutely want hard on hard...fuckin' duh... Quote Link to comment Share on other sites More sharing options...
Alpinfox Posted September 16, 2008 Share Posted September 16, 2008 your point was wrong...you absolutely want hard on hard...fuckin' duh... Â convince me. Quote Link to comment Share on other sites More sharing options...
RuMR Posted September 16, 2008 Share Posted September 16, 2008 (edited) do us a favor and start girth hitching your slings to your nuts...and start girth hitching your slings to bolt hangers... Â just think how many biners you'll save! please report back your findings...better yet, hold that thought...we'll read about it in the newspaper next monday... Â dumbass... Edited September 16, 2008 by RuMR Quote Link to comment Share on other sites More sharing options...
hafilax Posted September 16, 2008 Share Posted September 16, 2008 There's a story of Kate (AKA hold2please) on RC.com taking a huge fall as a result of girth hitching screamers to rivet hangers. After a string of rivets her next hanger fell apart and she took a whipper. As she weighted each rivet the screamer activated, ripped to the end and then the sling sheared off of the rivet hanger. This happened for like 12 rivets until she came to a stop. Â So yeah, girth hitching a sling to a nut would be a bad idea. And bounce test those rivet hangers on the ground. Â As for hard-hard connections I think the issue is torquing the biners if things are too rigid. This isn't an issue with biners on bolts because of the geometry but it does make back-clipping an issue on bolts whereas it isn't really an issue with gear placements IMO. (And one more for effect ISSUE) Quote Link to comment Share on other sites More sharing options...
tomtom Posted September 16, 2008 Share Posted September 16, 2008 The knock on clipping biner to biner is that in some orientations, it's easy to twist one and get it to pop out of the other. Two locking biners clipped together is pretty bomber. Â Regarding the op: Back when we were all climbing on 1" webbing, girth hitching runners was no issue. As the bdel data indicates, however, as one or both slings become thinner, the joint becomes progressively weaker. Personally, I would do it in a pinch, but I wouldn't make a habit of it. Quote Link to comment Share on other sites More sharing options...
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