Getting a new Beal 8MM rope (glacier travel) and wondering what size cordelette will work best for prusik's....6mm? or am I going to have to go smaller? Keep in mind they rope may be wet and iced.

I've been using 6mm on my 8mm rope, it's worked well (I loop my prusiks 4 times minimum).

Elves can this be move to GEAR please? (cms this is a topic for the gear thread, we understand but try to be diligent )

Generally for prussiks the rule is 2mm smaller than your rope. Hence a 10mm rope can take 8mm prussiks (though nobody uses prussiks that big). For an 8mm I'd use 6mm, granted 5mm will bite a little better but is also more prone to freezing itself onto the rope... and besides you get well over 1.000 lbs more tensile strength out of 6mm vs 5mm... and you'd be amazed how much force you can multiply on an anchor. So I'd use 6mm.

I'm a big fan of pre-rigging, in controlled environment I've gone from arrest to full 6:1 pulley system in under 2 min... too bad I can never find a partner that can Anyway dial your system in before you leave...

-Scotty

THOUSANDTH POST! Yay for me

-Scotty

The general rule of thimb is that the Prusik cord should be 60-80% of the size of the rope. I use 5mm for my 8mm glacier rope. You should be able to use 6mm on an 8mm rope if you wrap it 3 times to prevent it from slipping. I would definitely test it on your rope first before you use it in the field by hanging a sling/biner over a branch or rafter in your yard or garage and weight the Prusik cord.

Edit: A 5mm cord is better than 6mm for an icy rope.

Alpinist wrote:...A 5mm cord is better than 6mm for an icy rope.

- Or as alternative:



See also:
http://www.gudelius.de/fb1.htm

riverman wrote:- Or as alternative:

[...]

See also: http://www.gudelius.de/fb1.htm

Yes, this works very well, though I have not tried it on iced ropes.

Thanks guys. I'll get some 5 and 6 and try it out and see which works best.

And yea scotty everything will be pre rigged ready to go prusiks stuffed in pockets. As you know from my other thread were a two man team...so everything is geared towards being safe and for quick action.

Ps....Sorry about the wrong forum. Im new here

Are you worried by the low melting point of Dyneema?

Thinking of using Beal Dyneema 5,5 mm for Prusiks on my Beal 8,1 mm Ice Line. Does anyone have any ideas? Is Dyneema too slipery for prusiks>
Thanks

brenta wrote:Are you worried by the low melting point of Dyneema?

I'm not.


I'm worried about the slipperiness of the Dyneema (not to mention the wide surface area of the sling) not biting onto the rope.

My prussik loops are always Perlon.*


*Obviously, if I'm 30' down in a crevasse and all I have on me is a Dyneema sling, of course I'd use it to prussik up/out, but I wouldn't pre-rig my glacier travel kit with Dyneema sling-based friction knots. YMMV, of course...

Alpinisto wrote:I'm worried about the slipperiness of the Dyneema (not to mention the wide surface area of the sling) not biting onto the rope.

Give the FB-sling knot a (safe) try and see for yourself. The reason why it works is explained in the link that Herr Bachmann posted. The fact that the sling runs freely through the loop formed by the overhand helps in translating the load into friction force and also makes the loosening of the hitch easier once the sling is unloaded. The flat sling also wraps around the thin rope more easily than cord.

As a disclaimer addressed to everybody in general and no one in particular, master each technique and know its limitations before committing your safety to it. Don't use a Dyneema sling in any application in which significant heat may be produced through friction or otherwise transfered to it.

Examples: Ascending stuck rappel ropes: yes. Rappel "third hand": no. For glacier travel, I'd still pre-rig Prusiks, because I have not tried the FB-sling knot on frozen ropes.

I use 4mm and replace them very often. If it's going to see any sliding (rap backup) I'll use 6mm - but I'm also less concerned with holding power when it's on the brake side of an ATC.