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bogartontheslope

Rope differences, double, single twin

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I'm trying to understand the difference between a single, double and twin rope. Is it just a matter of one has a mark at the middle and different color ends? When is each used or does it vary?

 

I apologize if this is addressed in another thread.

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Single is a rope rated for use all by itself. It's what you generally see folks yarding on while climbing their sport routes, etc.

Twin is a pair of ropes (i.e. 2 60m ropes) that are not rated to be used as a single strand. You clip both through the protection. Benefits = Full length rappels and you don't chop your only rope when following during ice climbing.

Double is similar to a twin rope, (i.e 2 strands). The difference is that with a double rope you clip only one of them through each piece. Benefit = same as twin, except that you also can reduce rope drag on wandering routes, by clipping gear on your left only with the left rope, gear on your right with the right rope (i.e. the rope doesn't zigzag much hence reducing friction). Anyway, I bet if you search this forum you will find about a million posts on this topic. Elsewhere too.

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It varies.

 

The color/weave pattern differences you describe have nothing to do with whether it's a single/double/twin.

 

Single ropes are just that...a single line, usually from about 9mm up to 11mm. This is the most common system in use and is generally fine for most rock routes, the exception being a route that wanders all over.

 

Doubles (also called half ropes) are generally smaller diameter, say 8-9mm. The climber is tied into and belayed on both ropes and clips only one of the ropes through each piece of protection, generally alternating the ropes if the climb goes straight up, and using one rope on one side (say a red rope for pieces out left, blue on the right) if the route wanders...(this is simplistic description) . You can imagine the horrendous rope drag you can get on wandering pitches where a single rope would have a bunch of sharp bends in it as it zig zags between pro, even if using long slings on the protection. Another advantage to this system is that you can rappell the full length of the rope since you have two. With a single rope system, you may have to carry a "tag line"..i.e. a smaller dia piece of rope specifically to pair with your single rope while doing long raps.

 

Twins are even thinner than doubles/halfs, typically around 8mm, and are used almost like a single rope...you clip both strands through each piece. These are a decent choice for ice routes where you may be afraid of cutting or puncturing your rope with crampons/tools and often want the ability to make full rope length rappels, and value a lightweight setup.

 

That's a short description. Google should give you plenty of reading.

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One thing to add, is that double (half) ropes are generally rated to take a few falls on a single strand. This gives you the option of having two followers, one tied to the end of either rope, since falling while on top-rope does not generate anywhere near the forces that a leader fall does. Of course, that is if the belayer isn't giving the followers penatly slack for having to be rope gunned up the pitch. :tup: :tup:

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Anybody know the harm with a single twin line for glaciers or as a safety line on 4.hard/5.easy?

It's what I indend to use on this type of terrain and the weight of the rope is hard to beat.

Pretty much looking for protection from "slipping-type falls" and not full whippers when a stronger cord is clearly called for.

 

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I like that system. I use Ice floss when roped travel on a glacier is what I am doing. They are fine for a cravasse fall or catching someone on arrest. For a short headwall or climb out of a bergshrund I just tie in to the middle and lead as for a 1/2 rope. The weight savings is nice.

 

The drawbacks I have encountered are; 1)I needed to go to smaller prussicks. Keep that 2-3mm difference and it is fine. 2) It limits you to a little over 25m if you are folding a 60m in half. 3) In just about any cravasse fall the single piece of floss can cut deep. Dropping a second line or real careful padding is a must.

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The manufacturer will tell you not to do it. I wouldn't recommend it on rock under any circumstances, maybe on glacier, if it was a nice, mellow glacier that I was pretty sure I could avoid a crevasse fall. Prusiking up 8 mm would be hard and rigging a z-pulley would also be hard because it is so stretchy.

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Kevin grab the 8mm genesis for easy rock,otherwise I just take my twin(7.5mm) and fold it in half and climb 30m pitches which is about all you need on most alpine 5.8ish climbs

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Kevin, if you are simulclimbing with your half rope, you probably have considered folding it in half anyway to reduce the drag? My concern would be that the type of falls I would expect to see in this catagory (low 5th) would be non-vertical falls that could result in dragging the rope across edges and pendulums. If that's the case I would probably want it folded in half anyway? Just a thought.

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