Using double ropes as twins

I have a set of Petzl dragonflys (double ropes) I've been using for trad for a couple years now. If the route wonders, I use them as double ropes but if the route is straight, I use them as twin ropes (ie clipping them together into each piece).

Someone made the comment in passing that they didn't think you could do that because of the impact force being too high in a fall. This got me thinking so i researched the issue and I've seen mixed advice on the internet. I'm curious what other climbers think or if they've had experience using doubles as twins in a fall.

I am just suppressed that you have gotten a “couple of years” out of some Petzl Dragonfly's!

My 2 cents is its going to hold. I mean its not as if the rope is going to snap?I hear it stresses the gear more, but I'm sure it's not close to the 10-14kn most gear is rated at. I'd be more worried about that senario on ice. Ive climbed that way many times with no issue on both ice and rock. The impact force may vary, but unless your running things out 20-30 ft im sure its not that signifigant. I now climb with the Sterling Photo Fusions which are rated as both twin/half. It's a great solution to this problem.

I've heard of that as well but, never really gave it much thought. When I am climbing on double ropes on route that is straight, I usually just alternate which rope I clip. Kind of nice if you want to clip a piece high as you won't have an armload of slack out on the previously clipped rope if you slip.

That being said I have used them as twins and fallen. Seemed fine but, the piece was solid.

There is no such thing as double ropes. There are ropes rated as "twin ropes" and "half ropes"; some are rated as both. Both twins and half are used as a pair, but clipped differently. Using twins as halfs, or visa versa, can impart high impact forces on your pro. Find out what ropes you have and learn the difference between halfs and twins.

BirdDog wrote:There is no such thing as double ropes. There are ropes rated as "twin ropes" and "half ropes"; some are rated as both. Both twins and half are used as a pair, but clipped differently. Using twins as halfs, or visa versa, can impart high impact forces on your pro. Find out what ropes you have and learn the difference between halfs and twins.

I have a pair of Mammut Genesis 8.5mm half ropes. Mammut says you can use them as half ropes (DRT) or as twins. I've done both but usually use them as half ropes.

I've also paired one 8.5 half rope with a 10.2 single rope and used them for DRT. I would NEVER use this combo as twins.

BirdDog wrote:There is no such thing as double ropes. There are ropes rated as "twin ropes" and "half ropes"; some are rated as both.

BirdDog wrote:There is no such thing as double ropes. There are ropes rated as "twin ropes" and "half ropes"...

wivanoff wrote: Then why is it called DRT (Double Rope Technique) and SRT (Single Rope Technique)?

"Double rope technique" is commonly understood to mean the technique used with double/half ropes. That is, clipping one at a time.

Ratings have concrete numbers for how much force they put on a placement in a test. If you could use half ropes as twins, the manufacturer would probably have had them rated as twins as well. If the rope is rated only as a half rope, it means the UIAA thinks you shouldn't use it as a twin.

It might work, but go outside these guidelines at your own risk.

This topic comes up every year or so, and most folks are quick to point out the concern with the higher impact force. And rightly so.

What no one points out, is that the fall factor also affects impact force. Once you get a few pieces off the belay, the impact force of half-ropes-used-as-twins is no longer a real concern (huge run-out whippers excluded, of course). It's still going to be lower than if you fell on the first piece using conventional single or half rope technique.

Heck, climber weight probably has a greater effect on impact force than how you use your half ropes.

Here's what I got from Steph Davis blog citing Dave Furman, Mammut USA’s hardgood expert.

highinfatuation.com/blog/st…

Steph seems to imply that a twin must always be a twin, however a half can be either a half or a twin.

I will note, according to the manufacturers, half ropes should only be used as half ropes and twins only used as twins, unless expressly rated for both. The idea being that twins are always tested together under the same conditions as a single rope using 80kg and the halves are tested singlely using 55kg loads under the assumption that they will stretch enough to engage the second rope in a normal one piece per 8-10ft, "I just missed my next placement and peeled" scenario.

However, like the OP the exact nuances of why two stronger ropes in one piece of pro is not a good idea have never fully been explained. I hear there's a good article on UIAA.org but I can't find it for the life of me...

It's just because they don't stretch as much. It has the same effect as using a single piece of less dynamic rope, which transmits higher forces to the piece of gear.

I believe the half/double rope is tested by itself because it should be able to catch the fall on it's own, the other rope is there for backup, but I could be wrong about that.

What happens if you clip both ropes together ?
The impact force increases by 20 to 25% on the clipped point.

Above from Beal's website. Link: beal-planet.com/sport/angla…

As another posted said, climber weight, length of rope out, etc... all affect fall factor/impact force. As long as you are aware of the greater impact forces, you're probably fine using halfs as twins.

The Dread Pirate Killis wrote: but three ropes through one biner is EXTRA safe, and four is just dandy!

There is a great post in this thread by RGold on Double Ropes.
mountainproject.com/v/doubl…

Here is another great post.
mountainproject.com/v/can-i…

Given RGold and Jay's expertise in physics, I would tend to believe what they have to say.

To finish the thought, I reached out to Petzl and here is the response I got:

"Petzl's Dragonfly rope is a half rope. Generally speaking, half ropes can be clipped independently or together. However, when protection is marginal (ex. Ice screws) ALWAYS clip half ropes independently to minimize impact force in the event of a fall. If the protection is bomber (ex. bolts) you can clip both strands into the same draw. It is advised to NEVER alternate these two techniques on the same pitch. This is due to the fact that a fall could cause abrasion between the ropes where they are clipped to the same piece, but moving at different rates."

Galen Rahmlow wrote: It is advised to NEVER alternate these two techniques on the same pitch. This is due to the fact that a fall could cause abrasion between the ropes where they are clipped to the same piece, but moving at different rates."