I've just had a quick read through the thread and the links, however a significant thing missing from the calculator is what type of knot is used. Tensile test data collected over the years indicate that a double figure 8 knot weakens the rope at the know by about 33%, a bowline 50%. So although your bolts might be strong enough, your harness strong enough, your 3 year old rope which you're being belayed might fail where it's tied off to your harness. The killers for rope are knots, UV light, dirt inside the core, abrasion and heat generated when you're being lowered off or abseiling on it. |