Cordalettes and rappel back ups

Is there a preferred size of cord to use when making a cordalette and rappel back ups?

Cordolette: 7mm diameter, 6 meter/20 foot length.

Rappel backup: 6mm is super common. I wish I could tell you the length off the top of my head, but if you want to be careful you can tie it, adjust it, and then cut it once you're sure of the length for your setup. Or just cut twice.

Both are often tied with a double fisherman's.

I prefer the 5mm for an autoblock since it bites better on my skinny rope. It's about 30 cents a foot at REI so go crazy and buy a few feet of both sizes and see what you like better.

Cordelette 7mm, 23ft.  Ideally when doubled over twice it should be as wide as the shortest wingspan of your partners (or you).  This makes it as long as possible without being too long and unwieldy.  You can always easily shorten a cordellette, but you can never lengthen it without adding additional gear.

friction hitch, 6mm, make it the perfect length so that you can tie an autoblock and it can wrap around one rope 4 times or two ropes 3 times with about an inch or two left over.  I think it's roughly 3ft of cord (or a little less).  6mm is stronger than 5mm so will be safer for self rescue if needed and it still bites plenty good.

rockklimber wrote: 6mm is stronger than 5mm so will be safer for self rescue if needed and it still bites plenty good.  

FYI, the cheap 5mm PMI sold at REI is rated to 5.8kn and the 6mm is rated to 7.5kn. Either one is more than safe for use in self-rescue, load transfers, ascending a rope, etc.

Jack Servedio wrote:

FYI, the cheap 5mm PMI sold at REI is rated to 5.8kn and the 6mm is rated to 7.5kn. Either one is more than safe for use in self-rescue, load transfers, ascending a rope, etc.

Those rating are when the cords are new, havent been in the sun or seen any friction and dont have any knots.  So now you are comparing maximum 900lbs to 1200lbs when new.  I’ll take the extra 300lb margin 

Sterling and Bluewater also make sewn prussik third hands in different lengths. They are pretty sweet, and seemingly will last forever.

For a cordalette you can use 7mm or 6mm perlon, or use the 5.5mm spectra cord.  All of the guides I've climbed with use the Titan/spectra cord.

But I switched away from a cordalette to using a 240mm thin sewn runner. Not much difference in practical use, but are much lighter.

I also use and generally prefer a 240cm runner for most anchors. Something like BD Dynex works well. I also carry some cord (not tied with a fisherman) for tricky anchors and rescue purposes. Having both seems excessive, but many it makes many rescue situations MUCH easier, and the 240 weighs nothing. 

I like the 240 dynex slings too..... until I have to untie them haha

Z Winters wrote: I also use and generally prefer a 240cm runner for most anchors. Something like BD Dynex works well. I also carry some cord (not tied with a fisherman) for tricky anchors and rescue purposes. Having both seems excessive, but many it makes many rescue situations MUCH easier, and the 240 weighs nothing. 

this.

Noah R wrote: I like the 240 dynex slings too..... until I have to untie them haha

Use a clove hitch for the master point, then you can just remove the 'biner.  Google "Clove hitch master point" and there is a video...super easy.

Noah R wrote: I like the 240 dynex slings too..... until I have to untie them haha

Use a figure eight or figure nine instead of an overhand and it will be much easier to untie.  

good rule of thumb for making a prusik from cord: the diameter of the prusik cord needs to be 2-3mm smaller than the rope it will be installed onto. i find that 5/6mm works fine for most all recreational climbing ropes.

rockklimber wrote:

Use a figure eight or figure nine instead of an overhand and it will be much easier to untie.  

I knew someone would say that. And I do when possible. Sometimes there is not quite enough left to get the 8 in without making some wild angles and you have to overhand. I will check out the clove hitch @Buck

Noah R wrote:

I knew someone would say that. And I do when possible. Sometimes there is not quite enough left to get the 8 in without making some wild angles and you have to overhand. I will check out the clove hitch @Buck

Yeah, thats because 240cm is about 3ft too short for a cordelette.  

Buck Rio wrote:

Use a clove hitch for the master point, then you can just remove the 'biner.  Google "Clove hitch master point" and there is a video...super easy.

Just keep in mind that there will be no master point for the follower to clove into when the arrive at the anchor.  

you can use a big hms biner as a masterpoint, and a 240 sling plus an alpine draw or a double length sling can cover you in 99.9% of situations.

Russ B wrote: you can use a big hms biner as a masterpoint, and a 240 sling plus an alpine draw or a double length sling can cover you in 99.9% of situations.

So much unnecessary extra gear and tricks that are easier taken care of by a slightly longer cordelette.  And you get a nice top shelf to boot. Too each their own.  

Girth hitch instead of clove also works.

*EDIT It doesnt slip significantly, nor melts dyneema. Its used in the Alps, called "Sud-tirolean anchor"

Russ B wrote: you can use a big hms biner as a masterpoint, and a 240 sling plus an alpine draw or a double length sling can cover you in 99.9% of situations.

Ask yourself if you even need or want a cordalette/240cm sling, depending on where you climb, what anchors are like, etc. You can do a lot with an alpine draw or 2, and a few extra carabiners. During my cordalette years, I used a 5.5mm spectra. Simplified greatly since then.

Cord: 21ft 6mm powercord
Prussik: 4.5ft 6mm cnylon