When I was the IRATA training committee chairman some years ago I organised a Trainer and Assessor workshop at the Petzl factory in Crolles. We had some very detailed guided tours of all the production lines and testing facilities both in Crolles and at the old Charlet Moser factory up the road where I think they still make carabiners, ASAP's and Shunts, as well as ice axes and crampons.
We were told that all Petzl products will have a minimum breaking strength which is always between 10% and 20% more than what is marked on the product. If a product fails to be at least 10% stronger than the marked figure when they do a destructive test on a product from a batch, they will usually scrap the entire batch. Maybe this has something to do with the 1kN (10%) discrepancy with the Type L?
The problem with knotted rope terminations is everyone will tie them slightly differently. Based on the state of some of the knots we see during the Hidden Earth blindfolded knot tying competitions, most people have little understanding of the need to properly dress and set a knot. We lose enough strength as it is when we tie them correctly!
Knowing the people in Petzl as I do, they will almost certainly have tested the Segment with properly dressed and set knots but also, with the more likely, poorly tied knots, with the poorly tied ones possibly relating to the 10kN figure? This way Petzl are putting the responsibility for ensuring the 11kN termination strength firmly in the hands of the end user?
I'm with Fjell on the thinner rope diameters. Being in the rope access industry for the past 37 years I've always had an endless supply of new and slightly used 10.5mm and 11mm ropes, so that's what I've generally always caved on.
At one building inspection company that Badlad and I worked for in Sheffield in the 80's and 90's, we were issued with a 200m length of Beal 10.5mm which we folded in half and fed, middle first, into a large tackle bag. When we removed the old rope from service at the end of the year there was usually always at least 60m of rope in the bottom of the bag that had never been used. Bonus.
I never feel 100% comfortable when I'm using 9mm and even less so on the odd occasion I use an 8mm accessory cord. Badlad and I went down the last pitch of a 754m (ish) deep cave in Austria on a length of Beal 8mm accessory cord in 1988. Any rub points would have been totally unacceptable and there was a slight one. We decided to install a deviation when we probably wouldn't have bothered with a thicker rope.
Most of the fatalities in the rope access industry were caused by EN1891A ropes being cut when passing over or against a sharp or abrasive edge. You've got to be bloody careful to avoid any rub points on Type B ropes and extra, extra, bloody careful when using Type L (Washing Line).
As Fjell says, the thicker diameters usually work out a lot less expensive than the thinner more specialist ropes due to their much bigger production volumes.
Ian brings up an important one about some of the techniques we use. I have always used a basic Frog technique. It used be 10 steps, take a rest. but I have noticed the number of steps reducing and the rests are getting longer. I tried a Pantin when they first came out but just didn't get on with it at all.
I've run the Hidden Earth SRT competitions nearly every year since 1998 and have seen some interesting set-ups over the years. Some were bloody lethal if you needed to take a rest. What struck me this year, particularly on the 30m speed race, was the jerkiness of the movements during the climb. I know it is a competition and they might not do this down a cave, and its not easy when the rope you are climbing is moving downwards all the time, but if they did use these same jerky movements in a cave, and on a Type L designated rope, it could apply some pretty big forces to the already low strength of the knotted termination. When Lyon Equipment carried out an HSE review of rope access equipment many years ago, their testing showed upwards of 2.5 x the technicians body weight could be applied to the anchors during very heavy descender braking. I can't imagine it would be anything like that for ascending but it will likely be a bit more than body weight.
I'll bring my load cell to HE next year and we can measure it.
I think I'll stick with my Type A.
