As topcat alludes to, the problem with spits was that given cavers were mean, they took the hanger away with them. So every trip required a bolt and hanger to be inserted. In some places that would mean several times a weekend. Inevitably they wore out.
Thanks for clarifying the fundamental problem with spit-type anchors (including Rainoxes). That makes perfect sense. In the context we were using them, that particular problem wasn't likely to ever show itself. It seems obvious now you've said it!
I hope I haven't distracted too much from the relevant discussion of resin anchors by mentioning Rainoxes. I was just curious; thanks for your patience!
Quite apart from wanting to do the best job I could when making such an important decision, I would be very aware that it has been many years since "OK, that's fair enough, it may not have been the best bolt but it was a good practical option" is something likely to be said by relatives of a caver who has sustained life-changing injuries as a result of bolt failure.
I feel a bit heartless for saying this, but surely the "someone might die" argument can always be ratcheted up another notch of theoretically improved safety. But how much does it genuinely increase safety to do so?
Relative strength of anchors is largely a non-issue when the weakest link in the safety chain is the rope-ascender interface (about 4 -- 6 kN). It doesn't matter how strong your resin anchor is when your jammer destroys the rope.
What about security/reliability of anchors? Sensible rigging requires that, if any one anchor should fail at the worst possible time, the caver will remain safe and will certainly not suffer any serious injuries. In the case of resin anchors especially, the probability of a single (correctly installed) anchor failing is extremely low.
Let's say that the chance of one resin bolt failing on a given use is about 1/10,000. Then the chance of two failing at the same time is about 1/100 million. That figure is probably far too pessimistic. My actual guess would be closer to 1/100,000 for one resin anchor, giving 1/10 billion chance for simultaneous failure of two resins.
Of course there are specific situations where multiple simultaneous anchor failure is a real danger. For example, we know that multiple resins have failed together in highly corrosive sea environments. We also know that anchors installed right next to each other are dependent: if one fails, it may cause the other to fail. (Do we know of any other possibilities?)
And of course my hand-waving figures can be debated. But how many resin anchor failures do we even know about, other than those in seaside areas due to salt-water corrosion? Even with spits, anchor failure is rare.
Sadly, there are still plenty of serious accidents in caving. I hear about (and know) people who abseiled off the end of a rope. I hear about (and know) people who lost control of an abseil and hit the deck. I hear about (and know) people who fell off an electron ladder without a lifeline. I hear about (and know) people who were hit by falling rocks. I hear about (and knew) people who drowned.
Some of these people got away with minor injuries. Some of them were seriously affected. Some are dead.
I don't hear about, or know, anyone who has been injured from two bolts failing at the same time. And there are a lot of people who have done a lot of caving on some really grotty bolts.
That is not to say that we should accept poor bolts. The resin anchors installed in the UK are
superb, and everyone involved deserves our thanks. The IC anchors look excellent too and I hope the project succeeds and makes the whole topic moot. But when all commercially available products have been rejected because they are imperfect, I wonder whether we've lost perspective.
Yet equally I recognise that I know far, far less about the subject than the people involved. Perhaps I place too much faith in commercial anchors. I suppose when you're used to hanging off rather shocking-looking anchors -- I recall an ancient heavy-duty pair that appeared to have become mostly gel, which was rather alarming to see just after flinging yourself over the knife-edge pitch head balcony -- then any kind of resin feels like an enormous luxury.
For myself, I'm grateful for the splendid P-bolts that I use. I'm also happy to use existing Spits, especially when there are not enough P-bolts to ensure safety; there are many cases where the rigging becomes safer by using one. And in the spirit of cooperation and respect, I refrain from adding anchors even when I know there aren't truly enough of them to rig perfectly.
