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yomomma
May 3, 2004, 10:14 PM
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Registered: May 26, 2003
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Other than weight, what are the disadvantages of using two 10.5 mm ropes as doubles? Sometimes I'd like to have doubles to avoid rope drag, but I don't have the cash to spring for a skinny pair.
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dredsovrn
May 3, 2004, 10:29 PM
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Registered: May 24, 2003
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Other than the oppressive weight of two 10.5 MM ropes. Hmmm. I don't know. I have a pair of 8.6's I like, but I would imagine that a lot of the drag saving advantages will be diminished with two fat cords. I know you can reduce the zig zag drag, but there is still a lot more drag with a fat cord through biners.
It should work though. Try to keep your pitches short.
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gds
May 3, 2004, 10:41 PM
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Registered: Mar 8, 2004
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"Other than weight"
I can't imagine pulling up 2 X 10.5s after 120' are out.
Are they 60M? Then I really can't imagine pulling them up with 180' out.
I don't mean this to be rude but 10.5's are pretty beefy as a single. Two of them is a lot of rope.
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vegastradguy
May 3, 2004, 10:42 PM
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good lord, the weight would kill you. i did something similar a couple weeks ago (trailing a line, but clipping into critical pro) and the weight, not the drag, KILLED me. imagine 25lbs tugging you down.
if you want to avoid rope drag, learn how to sling your gear properly. i ran singles for a long time and only rarely encountered any serious drag. learn to read the line in front of you and use 24" and 48" slings properly and you shouldnt ever need doubles.
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mreardon
May 3, 2004, 11:30 PM
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Registered: Jun 17, 2002
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Isn't that something ridiculous like 20 pounds worth of rope? That could only lead to trouble. The other obvious disadvantages are your belayer having to deal with the headache of the weight at the belay which will create more clustering, and the rope drag cannot be better with a thicker rope.
There is a price difference, but the next time you are seriously considering a new rope, work a little overtime and splurge :D
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dirtineye
May 4, 2004, 12:28 AM
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Registered: Mar 29, 2003
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Good lord don't do this!
If you were to take a big fall and land on both ropes, it could be dangerous, as the impact force from a single rops is usually much greater than for twins or doubles.
Double ropes are designed to catch you on one or both ropes, but they must be clipped alternatley even then. Some doubles are rated as twins or doubles, and even if you clip them both at the same level, there will not be a huge impact force even in the worst case.
But should you land on two single ropes in a big fall, you might get into trouble. I'm jsut going to guess, but since Max impact for a single rope can be as high as 9.6 KN if you got into a fall situation that woudl generate 7 kN impact force, but were on two such ropes and hit em simultaneously, tiy might get a 14 kN impact. Warning, I just pulled this out of my rear, better check it out with an authority.
Where is Rgold when you need him?
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keithlester
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May 4, 2004, 4:33 AM
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If its a choice between buying anothjer 10.5 or a skinny rope, you could use one of each for a stop-gap measure, then let your partner buy another half-rope.
The biggest problem, besides weight, will be the difficulties your belayer will have feeding two ropes through tight slots in his/her belay device, giving you enough slack for clipping, but you can avoid the high impact force problem by never clipping both ropes in any one piece of gear.
You can still get a progressive catch, but harder than if you were using half ropes.
So, is it worth the extra effort for the leader, aching arms at the belay, harder catch if you fall, increased drag................. you decide
Is there a reason why you dont want to use a single, the obvious one is double length rappels, but I cant think of another one, unless its for increased redundancy for general safety reasons. :?
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dirtineye
May 4, 2004, 12:59 PM
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Registered: Mar 29, 2003
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In reply to: ... but you can avoid the high impact force problem by never clipping both ropes in any one piece of gear.
Don't clip anything but twin ropes through the same piece of gear. EVen with ropes rated as twin or double, once you clip seperate you keep em seperate, and if you go twin you stay twin. IF you don't do this, then the ropes may run over reach other through the same piece at different rates, and by now you should know that that is a way to burn your rope and even cut it.
But still, you might clip your ropes at teh same level , say in a horizontal, on different pieces, but , DON'T DO THIS unless the ropes are rated for twin. with doubles you should clip alternately, and that means at different heights as well as on alternating ropes.
IT would matter more in falls with higher fall factor of course. Bear in mind that theoretical fall factor is actually MUCH lower than actual fall factor, if for no other reason than the dynamic ability of the rope is cut down to at least 60% for all the rope below the top piece. IN other words, the only section of rope that is acting at its full dynamic capacity is the rope between climber and the last piece of pro.
You can probably get away with bad technique most of the time, but why practice bad technique? When the chips are down, you will do what you ahve practiced without thinking most likely.
One more thing about maximum impact force, as rope ages it will transfer more force to the climber.
Back to the original idea, you could try using longer slings in strategic spots to lessen yoru rope drag. That is a lot cheaper than getting double ropes. IF yo are looking at wandering three tiered roof routes though, better get doubles.
One cheap solution is to buy short spool ends in doubles. You can get a 140 foot set of doubles from PMI for 100 bucks for example. As long as you are climbing single pitch crags, 140 feet will work in most places. This is also a cheaper way to acid test a set of ropes that you might want to get a full length set of in the future.
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