I finally have a few hours to respond to many of the questions.
For those of you who aren’t interested in this thread, please refrain from posting comments that don’t further the topic. It makes it more difficult for people who are to follow the discussion.
> What do you think the worst case load and WLL that a anchor should > be rated to are?
The anchor is a different issue than the biner block assembly, which is part of the rappel system setup at an anchor location. I will stay on topic to keep the thread focused on the biner block.
According to the paper I referenced, the WLL for ropes and slings is 200 kg. I think it would follow the biner block assembly should also meet this value.
The worst case load is more difficult to state because it depends on how the component responds to increasing loads, and the assembly is not well defined (more complicated than a rope to analyze). But if the recommendation that the carabiner is physically unable to pass through (more accurately, no part of the gate should be exposed to the other ring) the anchor point (whatever that happens to be), then the hardware if rated is likely to have plenty of margin.
It is up to the user to determine if the WLL of the rope they use derated by the clove hitch knot meets this 200 kg value. Aging should also be used in the derating.
> Its looks like some popular canyoning ropes have WLL between 333 > and 430lbs, and ultimate strengths between 5000-6000lbs. The WLL
Be careful when thinking about WLL values. Although the rope will be given a single value from the manufacturer, the WLL of a rappel system will depend on each component meeting its own values. And with the rope, the WLL will depend on how it is deployed (1 strand is different than 2 strands).
> 700kg/1540lbs. The manufacturers website states that the WLL is 1/5 of > the breaking strength, so an ideally loaded Rapide is worth 7700lbs.
I don’t know what you mean by “worth”, but you seem to be implying the tensile strength of the piece of equipment is the “true” value canyoneerers should be concerned about, and as long as their weight + gear don’t exceed this, then all is ok and you are acting safe? I disagree if so.
> Based on your experience what do you think the > appropriate safety factor is for the strength of the clove hitch
Put more precisely, how should the WLL of the rope be derated to take into account the reduction in strength due to the clove hitch? That is a good question and is one of the questions I have thought about. I’ve seen values posted to the internet between 35% and 75%, although none of them have references. I know it depends on the physical characteristics of the object the hitch is attached to. I think it should be determined using standardized tests, at least for the new materials and ropes being promoted.
Steve Newcomb Tucson, AZ
Stevee B
I appreciate the recent insight about gate orientation and loading (gate, locked or unlocked, vs rapide/ring). Also appreciate the highlighting of WLL reduction due to the clove and rope age. Should throw abrasion in there – clove hitches on biners can frequently be positioned as to pin against rock while loaded, and even abraded by side-to-side (“lateral” for you big brains) movement by the descending canyoneer.
— In Yahoo Canyons Group, “adkramoo” wrote:
— In Yahoo Canyons Group, “Steve Newcomb” makes > it more difficult for people who are to follow the > discussion.
> This commentary is allowed. As is commentary from those who feel the > topic is going round and round. As is commentary from those who are > interested, but feel the participants are more interested in making > their points and “winning” the disscussion, as opposed to really > learning. My personal commentary is that there has been many good > points and ideas and that there has been as many condensending > comments, easily matching any ridicule. It is a shame that one must > wade thru a bit of this on the way to important substance. Final > personal commentary? Life is dangerous. Adventure sports more so. > Being careful with the gear used and using the correct gear helps > make it safer. But we can’t talk and plan our way free of ALL the > risk. We discuss the rash of accidents and deaths to learn from them > and maybe to convince our mortal souls that if I pay enough > attention, it can’t happen to us. It can. Eyes open, plan well, live > a little and with skill and luck, die old, in our beds.. > Safe Passage All > Ram >
adkramoo
— In Yahoo Canyons Group, “Steve Newcomb” wrote: > For those of you who aren’t interested in this thread, please > refrain from posting comments that don’t further the topic. It makes > it more difficult for people who are to follow the discussion.
This commentary is allowed. As is commentary from those who feel the topic is going round and round. As is commentary from those who are interested, but feel the participants are more interested in making their points and “winning” the disscussion, as opposed to really learning. My personal commentary is that there has been many good points and ideas and that there has been as many condensending comments, easily matching any ridicule. It is a shame that one must wade thru a bit of this on the way to important substance. Final personal commentary? Life is dangerous. Adventure sports more so. Being careful with the gear used and using the correct gear helps make it safer. But we can’t talk and plan our way free of ALL the risk. We discuss the rash of accidents and deaths to learn from them and maybe to convince our mortal souls that if I pay enough attention, it can’t happen to us. It can. Eyes open, plan well, live a little and with skill and luck, die old, in our beds.. Safe Passage All Ram