Half and twin rope question.

Although overkill in terms of millimeters you're tied into, would it be safe to exercise a twin or half rope technique with two ropes rated only as singles? It is to say, are there properties that half/twin ropes possess that single rated ropes do not; thus setting ones self up for a "yer gonna die" situation. Thank you.

There's no problem other than weight (which is not insignificant) in using two single ropes as half ropes. I wouldn't use them as twins though (i.e. clipping both to a piece) because of the increased impact loads.

I've done it when leading 2 followers on multi-pitch and I didn't have a half/twin. The weight gets really bad when you are high on a pitch.

Yeah, it's a lot of weight. Especially when you link pitches.

I would say that using them as doubles wouldn't be so bad, but using both clipped into one piece could potentially increase the force on that one piece. I wouldn't clip two single rated ropes to one piece, but I don't see an issue with using them as doubles. Not to mention the weight issue already mentioned. Out of curiosity, if you need two ropes and only have singles, why not just have a second tag one? Seems like that would be much easier for both involved. If you do need two on lead, then it would likely be in a situation in which your alternating which is being clipped anyhow.

There was a time not that long ago that doubles were not even rated for twin use, much less single ropes. Since sport climbing as evolved, so many are learning the intricacies of climbing at the crag vs alpine (where you are taught the whys and hows of your systems). A consistent mistake in folks moving from sport to trad is not extending pro enough and particularly clipping directly into the rope(s) and/or using dyneema slings vs nylon or nylon hybrids. The more absorption of energy you can create in the system, the safer you are. Now you would be hard pressed to find doubles that are not also rated for twin use and of course they are making thin singles rated for double and twin.

Thank you everyone for your responses. This answered my questions.

They have to be used in half rope technique, not twin. But it's perfectly safe (as everyone said).

I do this sometimes when bringing up two seconds and only having singles avaliable.

The weight of the ropes can be an issue, but some people climb on fat doubles (8.8 to 9.2) and some singles are 9.5, so it's definitely more but probably not unmanageable. If you usually climb on 8mm doubles, it's going to feel like a lot more drag

Trying to spell out the rules on the different types of dynamic ropes . . . .

Half ropes are used in pairs but clipped separately.

A single half rope can be used for bringing up a second, so three people can climb with one pair of half ropes.

Any single rope can be used as a half rope, so a pair of single ropes can be used as a pair of half ropes.

A pair of twin ropes, together, are equivalent to a single rope: they are clipped into the same protection, side-by-side in the carabiner. There is no use for a single twin rope, including bringing up a second.

Some half ropes are soft enough (impact-force-wise) to also be rated as twins, which means that they can be used as either. Most people believe that these ropes should not be used as both halfs and twins on the same pitch (because of the ropes rubbing against each other through the carabiners in which they are "twinned"), but I am unaware of any evidence of anything bad resulting from combining half and twin techniques on a single pitch.

Some single ropes are also rated as twins. Since any single rope is also a half rope, the rope companies' marketing people point out that these ropes are rated as all three.

One other thought: An 8.5mm single rope is very different from an 8.5mm half rope. Odds are that that super-skinny single rope has at most 30% sheath, while the "fat" half rope might be nearly 50% sheath. Guess which one will last more than a few pitches.