Synthetic fibres -- objective performance ratings?

[Bob Pingel]

The figure 8 follow through was described as "ideal to attach two pieces of rope together" and was tested in that way. The testing machine had the belay points where you could "wind the rope around a drum and secure with a cleat".

I have had a few splices destructively tested, and they break right at the end of the taper. My understanding is that this from the stress riser due to the splice. They have all broken above the rated tensile of the rope itself, implying we did not know the true tensile before we started.

My view is that if we can splice to rated tensile (and manufacturers deliver rope at or above what they rate) and use a healthy safety factor -- I typically use at least 3:1 for running rigging -- we will keep rigs up and people happy and healthy. I suppose the ideal would be to break a section of rope off of every spool, but this gets expensive and I think the samples could vary as you work through the spool. I feel pretty good using these guidelines and then breaking a splice here and there to keep myself honest.

Bob