mkporwit Posted September 16, 2008 Posted September 16, 2008 ...actually, i think a girth hitch works like a knot in that some of the base material is compromised by the knot...i don't have the numbers, but a figure 8 fails a rope at something like 90% (again, i'm pulling out of my ass here)... Experiments show that a figure 8 fails at around ~70% of rope strength, which is about what I remembered. I was surprised that the bowline reduced the strenght more... Quote
RuMR Posted September 16, 2008 Posted September 16, 2008 that's why i said pulling it out of my ass... it proves my point that girth hitching weakens the system, but not enough out in the middle of a route to worry about it... Quote
sobo Posted September 17, 2008 Posted September 17, 2008 Good read, mk. As a reference point, the Mountain Rescue Association uses a reduction of 1/3 of rope strength in calculating the 10:1 goal for the static system safety factor (SSSF) for the addition of any knot in the system. So any knot in a 30kN climbing rope immediately throws it down to a 20kN working rope. That would mean, say, hauling a dead vertical load of 2kN (a victim, a rescuer, and a litter/other crap) is right at the 10:1 SSSF. Quote
mike1 Posted September 17, 2008 Posted September 17, 2008 Personally I would stay away from building a habit of girth hitching soft to soft as you're describing. I’d do it in a heart beat if I had to, but I just think it should be considered a last resort instead of a primary method. The loose sewn or tied slings are a much safer way to go as mentioned above in pindude's post. my $0.019999999999 Quote
Jens Posted September 17, 2008 Posted September 17, 2008 that's why i said pulling it out of my ass... it proves my point that girth hitching weakens the system, but not enough out in the middle of a route to worry about it... amen Quote
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