Using one twin/half rope for 4th/easy 5th class alpine climbing

Interested in feedback regarding use of a 7.8 mm twin/half rope for 4th/easy 5th class alpine climbing versus use of a standard 8.9 mm or larger diameter single rope. Is this an acceptable way to shave weight (5 pounds for a 60 m x 7.8 mm rope versus 6.9 pounds for a 60 m x 8.9 mm rope) for light-and-fast attempts where the technical climbing is well within the comfort range of the climber (but not so comfortable that he or she is willing to free-solo) or does it represent an unacceptable level of risk?

Just tie into the mid point and simul climb...

You have the full protection of the half and chances are you will simul climb the terrain...

D-Roc wrote:Just tie into the mid point and simul climb... You have the full protection of the half and chances are you will simul climb the terrain...

this is exactly what ive done in the past as well. one climber ties into both ends of the rope, the other ties into the middle. now you have 30m half rope. works great for simul.

there are a bunch of ropes out there rates for half, single and double if you really want the 60m to pitch your climb out. although a fall will be very long considering all the rope stretch.

I use an 8mm on alpine routes that have a lot simul terrain. If you have it doubled over as a 30m rope there is no change in risk IMO. If you climb on it as a single be aware the cut resistance is much lower and you will want two biners in your ATC to belay a leader.

I've used one 8.5mm Mammut Genesis double and I worried about durability more than rope stretch. I was a long way from the car if the rope gets (edit: damaged).

As far as rope stretch, I've fallen on one of my doubles using both ropes as doubles... I didn't feel like fell far. I had maybe 40 feet out. F-ing scary but seemed safe.

Good input! Thanks everyone.

I climb on one Beal Cobra 8.6 half rope all the time (not folded in half). This is my primary technique for mountaineering and easy alpine, up to WI2 and low 5th rock.

A 7.8 rope might make me nervous, at least on rock with sharp corners. Especially if it's a twin, which is nominally not rated to hold a fall by itself. You can definitely double up, as many people have pointed out, but if you're going to double up a 30m 9.X single rope is probably more sensible (assuming you don't need the ability to do long raps on a 4th class route).

Mammut makes an 8.7 mm single rope that ways in at 51 grams per meter which equates to 6.75 pounds. That's a light load combined with the piece of mind of a true single rope.

One half rope is fine for easy Alpine. Totally fine.

Jye-Rock wrote:Mammut makes an 8.7 mm single rope that ways in at 51 grams per meter which equates to 6.75 pounds. That's a light load combined with the piece of mind of a true single rope.

And a thinner sheath, a partner has used one for alpine and it got fuzzy a little quicker than I would like. It did hold up better than the Sterling Nano I use though.
The serenity is a good choice if you're looking for a super skinny single rated rope, but honestly a half rope will hold your lead fall on a single strand. I've taken two larger lead falls my 8mm phoenix, it holds just fine.

Numbers for fun:

8.7 Serenity is 51 grams with 38% sheath, so about 19 grams of the rope are sheath. Total rope ~6.7lbs

8.5 Genesis is 48 grams with 49% sheath, so about 23.5 gram sheath. Total rope ~6.4lbs

8mm Phoenix is 42 grams with 42% sheath, so about 17.6 gram is sheath. Total rope ~5.5lbs