Lightweight small diameter rope rappels

Hi, I’ve been getting into scrambling more in the boulder, CO flatirons and I’m trying to figure out a setup for rappelling off a couple of the formations that I don’t feel comfortable down climbing. I’m trying to keep everything as light as possible so I can still run the trails and not be weighed down, while still maintaining a high level of control on the rappels. I’ve only used 9-10mm ropes before so I’m just not experienced with the friction and use of the smaller ropes. I’m looking into a 8mm rope using an ATC w/ a prusick, but was wondering if I could go smaller. Say 7mm with atc and prusick, use a tag line, or a different rappel device? Thanks

I believe the BD ATC Alpine Guide is rated down to 7mm, so that may be a good option. I've been using a DMM Pivot with 8mm ropes mostly, but just got a 7mm dynamic rope recently, and the Pivot works fine for us rappelling even though it's rated down to 7.5mm. I think there is a mix of "rated for", which is objective, and "works with/for", which is subjective information you'll have to determine for yourself. Definitely try out something at home or garage or local crag before relying on it with your life. You'll find out pretty quickly whether it is sketchy or not.

my kit for that kind of thing is a Beal backup line (5.5mm), which is rated for rappel, and weighs about 2lbs for a 40m, and a Grivel Scream Plate, which is the only device I know of that's rated for a rope that thin. You can also put 2 carabiners in your ATC to get more friction on skinnier ropes, which I've done and felt safe.

I used the Petzl RAD line for the Evolution traverse and per their suggestion, used a munter. This worked well and with that rope, the kinks have been minimal. I continue to use this rope for alpine scrambles and the munter has been more than effective and I don't have to carry an ATC type device. 

Try the edelrid microl Jul device (designed for 6.9mm ropes) or use a super munter, it has significantly more friction than a regular Munter hitch on rappel

Once you get down to really skinny rope diameters friction hitches can be iffy.

Beal jammy or their aramid cord (same thing, just depends if you want it sewn or knot) bite much better on skinny rope than standard cord. 

A VT prusik (the hitch, not necessarily the bluewater ropes product) works pretty well if the diameter of the prusik cord is close to the diameter of the rope.

Edilrid Jul devices don’t need a third hand— they do get hot and eat carabiners, but if you’re only doing a single shortish rap that isn’t a huge problem and the convenience is worth it IMO. The microjul is rated down to 6.9mm, but I’ve only used the megajul so I can’t speak to how well it actually handles rope that skinny.

Rapped today on a Mammut half/twin 7.5 with my Pivot and a autoblock, no issues whatsoever. You can get going quick, but stay in control and with the backup, you'll be fine. 

My solution for a light rope for use only for abseils while scrambling was ordinary industrial type hawser laid polypropylene rope. I use 8mm which is much lighter for a given thickness than nylon etc. Mine is 23g/m and IIRC 960 kg breaking strain (any maximum workload figures will obviously be well below this as a safety factor). Being 8mm it can be used with normal abseil methods including ATC-XP, classic , and krab on long sling sitsling with rope over shoulder. Obviously you'd be using it double for retrieval and sufficient friction for abseil is not a problem, though I've checked I can ab on a single strand too. In practice I usually use the sitsling method. The lower melting point of polypropylene is not really a concern (I learnt to climb bottom roping with polypropylene ropes). The rope tends to kink easily but its no trouble for just the occasional abseil. Not a prime consideration but its also inexpensive.

i shore wrote:

My solution for a light rope for use only for abseils while scrambling was ordinary industrial type hawser laid polypropylene rope. I use 8mm which is much lighter for a given thickness than nylon etc. Mine is 23g/m and IIRC 960 kg breaking strain (any maximum workload figures will obviously be well below this as a safety factor). Being 8mm it can be used with normal abseil methods including ATC-XP, classic , and krab on long sling sitsling with rope over shoulder. Obviously you'd be using it double for retrieval and sufficient friction for abseil is not a problem, though I've checked I can ab on a single strand too. In practice I usually use the sitsling method. The lower melting point of polypropylene is not really a concern (I learnt to climb bottom roping with polypropylene ropes). The rope tends to kink easily but its no trouble for just the occasional abseil. Not a prime consideration but its also inexpensive.

6/10 

that guy named seb wrote:

6/10 

I assume you mean you think its a troll. Its not. Into the 1970s polypropylene rope (albeit thicker than 8mm) was commonly used for bottom roping on the small sandstone outcrops near London. I wanted a light rope for occasional abseiling but providing sufficient friction for usual methods of abseiling ie thicker than the specialist cords available. Polypropylene fitted the bill. Incidentally another useful property is it absorbs negligible amounts of water.

My glacier/skimo kit is an Edelrid RLP and a Petzl Reverso with two braking carabiners instead of 1, per Petzl's instructions for the Rad Line (which is also a 6mm "accessory cord" like the RLP). https://www.petzl.com/INT/en/Sport/Rappelling-on-the-RAD-LINE-cord?ActivityName=Ski-touring

If you're trying to go really lights, get the smallest cord you feel comfortable using (5.5 power cord?) and a munter. Try it out first and see if you need to use a supermunter. 

the super/monster munter has the added benefit of reversing the kink that the standard munter introduces on rappel.  

I personally wouldn't use any of those skinny ropes in the big mountains; eg. abrasion due to sheer number of edges & dislodged rock that may hit the rope. Too risky.

Have used 6mm static with super munter to rap a few times while solo mountaineering with a 40 pound pack.  But the cord was brought as a “just in case”, not routine use if that matters.

Would be interesting to see results from raps on a super munter using smaller and smaller diameters until failure - with backup of course. Would speed of rappel matter? Difference between rap weight upon breakage and advertised cord strength?

Oh yes - helmet is good idea.  Small rocks can split your scalp.

I personally wouldn't use a 6mm rope in sketchy terrain like the Matterhorn where rockfall, choss and rock where sharp edges abound, especially if multiple raps are involved. It's just too risky.

Helmet? In alpine ALWAYS. 

giraud b wrote:

I personally wouldn't use a 6mm rope in sketchy terrain like the Matterhorn where rockfall, choss and rock where sharp edges abound, especially if multiple raps are involved. It's just too risky.

Aye.

It sounds like OP is interested in a kind of circuit in the Flat Irons (CO).  While I've climbed in the Flat Irons, it isn't like I know them very well.  Still, the raps I recall were relatively clean.

My experiences has been that small diameter ropes often "speed through" even appropriate belay devices, making the ropes difficult/dangerous to control. I would suggest always wearing tough leather gloves to prevent possible skin burn while rappelling.

The “safer” way is certainly with a backup. That said, I haven’t used one in years, as i switched to a glove and never looked back. The security that a rap glove (the synthetic metolius can often be had for $10, full finger, thin enough for good dexterity) provides me is enough for my peace of mind. Ymmv, of course.

I’ve rapped single strand 7.3 w/ a glove, I certainly went slow but it was fine (w/ a pivot), and rap double strand 6.0 on a gigajul in atc orientation all the time (w/ a glove), and it’s super easy to control. Typically I used two biners for anything under 8mm on rap - more control, but also more weight…again, ymmv but a measly extra 75g should not kill the vibe on your easy flatiron scramble, IMO

Rad Line(30m) using a supermunter(or microjul), with a nice locker, on a bd couloir harness. This setup is LIGHT and will get you down pretty much anything... as long as your not completely in over your head   

Big B wrote:

Rad Line(30m) using a supermunter(or microjul), with a nice locker, on a bd couloir harness. This setup is LIGHT and will get you down pretty much anything... as long as your not completely in over your head   

That's the harness I use for this kind of crazy.  ;)