Cordelette and Equalette Material

Why do most discussions of these items almost always suggest using 7mm nylon which has only about 10 Kn tensile strength, about half the strength of an average biner?

Also anyone have a link to ez instructions on making the equalette? I have the John Long Book but it doesn't show in pictures how to make one. I particularly am baffled by the limiter knots.

7mm is standard cordlete material and the 10kN strength is for the one strand rope, whereas when it is made into a loop you have two stands however the strength is not quite double do to varying conditions. My personal guess is that if the rope is 10kN you will get almost 17kN out of a loop around something. I would actually have to do the calculations and it varies depending on what it is going around. This strength is generally more than the protection you place. as for the equalette, I thumbed through my books for a diagram but didn't see one. I have never used it, I have seen it used though. I am sure someone else on here can help you with that.

Try this photo:

cs.tut.fi/~jupsu/equalette_…

Three point equalized anchors have been sufficient for what I do.

I read of tests in which they tied a loop of 7 mm perlon cord around two pulleys with a double fisherman. The cord broke at the knot when the pull was around 18 kN. One strand of that cord broke at around 13 kN. The difference between 26 kN and 18 kN is due to the weakening effect of the knot.

The limiting knots in an equalette are typically overhands.

The strength will also very according to what you put it around, tight radiuses and corners are also weakening factors

Yes, that's why they used two pulleys. That way, the break was guaranteed to occur at the knot.

If I could remember back to my statics class I could find out weather the knot or biner would be the limiting factor. Would be a cool test though, someone has probably already done it. Because how often do you atach a pulley, not bashing what you found and say from this test or anything, it is probably the best way to show the los from the knot.

Exactly. That's what the tests were all about, and the pulleys not only had large radii, but guaranteed equal tension in the two sides of the loop.

Just out of curiousity, If you took said cord and tied it into a 3 point anchor, and used 3 different knots(one per loop) to tie it in to the harness/load. That should theoretically triple the strength, as each line would hold 1/3 of the load correct? Of course depening on the angles and what not... Although this would be a rediculous mess to deal with en route. so you should be able to take 10kN cord and loop it any number of times to get the desired strength, as long as each loop had its own knot to attach to the load.

I think what we need is a more-confusing anchor; so we can sit on a ledge and have a T-storm offer us a good smack-down.

I'm still happy with the 5.5 high-strength cord, slings, or climbing rope as the rigging.

7mm is standard cordlete material and the 10kN strength is for the one strand rope, whereas when it is made into a loop you have two stands however the strength is not quite double do to varying conditions. quote>

But then you would have to connect to the pro with a doubled double overhand or something else to give you a loop with two strands per side so your clipping two strands, and the pics frequently show a single strand running through the biner that attaches to the bolt or pro. Plus, the power point seems to be through one strand alot of times too which I don't get unless it has something to do with the equalisation function.

Even if you are creating a 3 legged or more anchor, the weakest part will be one of those legs which is still a single strand of 10Kn rope (even if it is doubled since you will only be clipping one strand). So I see how this system is probably ok for a belay anchor as long as the leader gets a few pieces of pro in, but it seems too weak for a top rope anchor unless your using stronger material.

The rating is for pulling on both ends of a piece of rope, make a loop out of it and the force gets transmitted onto both sides of loop essentially two ropes without losses from the knot and going over a tight radious such as a biner, anouther factor is the fricton on the contact surface which is anouther factor to add into what you are looping around. Use a double fishermans knot to tie the loop ends together.