Thinnest Static Rope for extended achors

Hi All: I have a mess of old 1" tubular webbing that I used for rigging extended toprope anchors (like trees 25' from the edge of a route). If I wanted to replace it with static cord, what would be the minimum diameter I should consider? Is 7 or 8mm nylon acceptable?

Does anyone routinely use tech-cord for this purpose, or is nylon preferred?

I don't top-rope that frequently, so durability is not a primary concern.Obviously safety is primary.

You could use tech cord which is extremely strong and less prone to abrasion, but it's stiffer so it does a poorer job holding knots. Keep an eye on the knots.

1" webbing is probably the most suited, and cheap.  But 7mm would be good too.  Anything less its going to get abrasions pretty easy over edges like already mentioned. Tech cord is great but mostly much more expensive for 25" than webbing. 

Unless you're hiking in super far and only want to be able to use it a few times, the thinnest I would consider is 9mm. Even that can get beat quickly if you have your anchor over an edge. 7-8mm will get worked super fast. I have a length of 9mm for my infrequent personal use- it packs down quite small. For work I use 10mm for my TR anchor set ups and after a year the cord can get well fluffed.

Considering that unless you're using directionals, your anchor point is going to be pulled side to side as you climb in different directions and abrading against the rock with the weight of two people on it, I wouldn't use anything smaller than 9mm for your own safety. If you've never seen it, you wouldn't believe how easily a loaded rope cuts when pulled across sharp rock. 

i use 6mm lines. that's about 8.5kN. more than enough.

Sterling 5.9mm powercord. 

Seems like 9mm is recommendation by some courses and groups.  Any idea why, if the strength is less than 8mm?  Why is 8mm stronger than 9mm?  The chart is from a sterling display at a local shop. If the recommendation is for higher durability, then why would the 9mm be more durable?  

I thought that was a typo but I looked on the Sterling site and the 9mm figure conveys. My guess would be the CE EN 564 standard that it is tested too (which is the only items that I'd buy). Also, possibly the 9mm has a thicker sheath for abrasion resistance? No idea... just throwing that out there.

9mm is probably tested under en 1891 which would explain why on the chart it gives odd results.

Rich zz wrote:

i use 6mm lines. that's about 8.5kN. more than enough.

Maybe "strong enough" but no way I'd go any smaller than 8mm, in the interest of durability and cut resistance.  Most of what I use is 10mm, but weight and bulk are not a real concern here.

And if the extension is going over a sharp edge, pad it.  I use an aluminum SAM splint which attaches to the rope ( I use 10mm for long extensions).  The splint weighs about 150 grams.

Stephen Bittner wrote:

Considering that unless you're using directionals, your anchor point is going to be pulled side to side as you climb in different directions and abrading against the rock with the weight of two people on it, I wouldn't use anything smaller than 9mm for your own safety.

Do what now?

Just my 2 cents, I used to use hose that I had cut down the middle to protect the rope going over sharp edges. Then I got lazy and bought those rubber rope protector things which seem to prevent excessive abrasion. Sometimes I would use them for protecting my fixed rap line when rappeling down to the anchor from above. But I would only really use the rope protectors when TR soloing because extra caution and all.