Mark Wright said:As Badlad asks above, where is the evidence of correctly installed resin bonded anchors failing catastrophically in normal use, or indeed carabiners or Maillons failing.
There?s certainly no evidence of it happening in the rope access industry where they are used significantly more regularly than in caves. Nearly all the fatalities in that industry are caused by ropes failing due to running over sharp edges and the back-up system not working.
From a Likelihood x Severity Risk Matrix Risk Assessment point of view the failure of a single anchor would still be considered a Low level of risk.
Yes, if the single anchor point failed you may well fall and die so the Severity of the consequences would score a 5, but as there is no evidence of them ever failing catastrophically the Likelihood would score a 1.
The Risk Factor can be reduced further by simply being extra careful not to shock load the system, or alternatively, wrapping yourself in a ball of cotton wool.
Mark
A fatality is always in the ALARP region so you are obliged to take all reasonable (and often unreasonable) measures to reduce the probability. Using two belays in a single-rope situation is not only plainly within the realms of reasonable, it is in every manual.
For me it is extremely simple - I am not going to expose my wife or friends to easily avoidable risks.
Legally you are just toast if there was an incident, and I am not sure insurance would stand up to it either. I imagine it would be childs play to portray as gross negligence - and widows, orphans and lawyers gotta eat.
I buy a 200m reel of rope about every year to rotate the stock, and have pretty much fixed on using 10mm in the Dales given you need about 250m at most, and usually much less. That 10mm Teufelberger is pretty good value, so what excuse do I have? When used with P bolts I am intensely relaxed and even chillaxed about gear failure. I am less sanguine about flooding given that sort of thing has happened to me, let alone "in the industry".
Then again, the "once in a million years" top event has also happened to me - it just proves you don't know about the unknown unknowns etc. Only the paranoid survive.