4 ms·
As a (washed up) climber, falling is something I think about a lot. It turns out that sit harness used by recreational climbers are unsafe. In a catastrophic fa
by bhickey 9y ago
As a (washed up) climber, falling is something I think about a lot. It turns out that sit harness used by recreational climbers are unsafe. In a catastrophic fall, the harness directs force into the lumbar spine in an anterior direction. An old study on industrial fall arrest found that loadings in this orientation can produce spinal injury around 4kN (don't quote me on this number, it's been a year since I read the paper.) It gets worse. If a falling climber rotates during the fall, load will be applied left-right above the pelvis. This orientation decreases the spinal injury threshold further.
A chest harness, on the other hand, loads the body in a vertical orientation applying compressive force to the spine. This pushes the survivability margin out toward 7kN and beyond the maximal loading forces you can experience in a factor 2 fall.
- yan 9y agoUnsafe for what? Almost all of the fall forces should be dissipated by a dynamic rope, not the harness.
- bhickey 9y agoVery high factor falls. A factor 2 fall can kill you even if you don't hit anything on the way down.
- yan 9y agoIf you're healthy and using a normal, dynamic rope, no it won't. It won't even hurt. A factor 2 fall onto webbing or dyneema can totally mess you up though, even from a couple of feet.
- bhickey 9y agoTake a 60 foot 1.95 factor fall and get back to me.
- steveax 9y agoYou'll want to retire that rope, but nope, I've had a couple of high fall factor falls with no ill effects. A true fall factor 2 fall is impossible to achieve in a real setting (knot, etc.), but I've taken a prob 1.6 or so.
- blackguardx 9y agoThe UIAA (climbing standards body) disagrees with you. The specs of climbing ropes are set by them to result in no injury in worst case falls. And plenty of people have taken factor 2 falls with no ill effect.
- bhickey 9y agoAnd industrial fall arrest literature disagrees with the UIAA. A 4kN loading will break your spine in the correct orientation.
- blackguardx 9y agoWorkplace exposure limits are always lower than injury thresholds.