Moderator: Tim White
Mike Hopley wrote:Extremeophile wrote:Again, if 10 years is the period of time to allow a sufficient margin of safety then why not share the data showing what that margin is?
I don't know. And neither do you, for that matter. But I'm prepared to believe that rope manufacturers might know more about their ropes than I do, regardless of whether they're sharing the data.
I would also expect that these lifespans are not determined by one simple set of data, but by careful consideration of the many ways ropes are used and abused. They will naturally set a very conservative lifespan to ensure sufficient margin. In most situations this means we retire our ropes several years (even decades!) before they actually break, which seems like a good idea to me.
I know cavers who had harnesses that were around 10 -- 15 years old, and were able to rip the harness in half with their hands. The harnesses seemed to be fine, judging by outward appearances. But don't worry -- you can ignore that information, because it's anecdotal. Only proper scientific evidence should ever be used to make a judgement about anything.
I think it's stupid to ignore the manufacturer's maximum recommended lifespan for textile PPE. The cost of rope (and harnesses, slings...) is trivial, and the consequence of failure is usually death. The reward of being "right" doesn't seem that attractive when compared to the consequences of being wrong.
bigredfoote wrote:I prefer rope to webbing for handlines. I don't know why, but I feel that I can get a better grip on rope than on the webbing shape. Maybe it's the flexibility of the webbing.
I also think rope is better since it can be used with equipment, where webbing can't. If you have someone with a bad case of nerves at the top of the slope, you can make a diaper sling harness and a munter hitch with a carabiner and give them some control down the rope. I don't think you can rappel down webbing as nicely and you can't use an ascender for a better handle going up.
Jen
NZcaver wrote:I don't have a huge problem with either, but tend to whatever is available (usually webbing) as a temporary handline versus usually rope for a more permanent rigged handline. I don't mind grabbing onto webbing, but there is certainly a difference in "grip-ability" for me between the old standard tubular webbing with a prominent ribbed weave and the shiny smoother stuff made by Blue Water etc that you often see in stores these days.
Mike Hopley wrote:On expeditions, we've often left ropes (derigged and coiled) in the cave for the next year. We limit this to about three years total, and then replace the ropes -- but of course it depends on the situation, and we take advice from an expert...
PeterFJohnson wrote:I had always heard that the military spec was less abrasion resistant - but this was completely anecdotal. Anyone know whether there is any truth to that?
PeterFJohnson wrote:But if it is grip people are looking for the best bet might be larger(1/2 inch+) diameter nylon line with a high breaking strength - perhaps even something braided or plaited.
Extremeophile wrote: A lot of fixed ropes end up being retired due to wear, but there seem to be very different opinions on whether to replace a rope on the basis of age alone. This is complicated further when the history of the rope is not known. PMI includes a tracer in the core of their ropes, so the approximate age can be determined, but other manufacturers (e.g. Bluewater) do not.
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