Breakcord

[Calvin19 0]

i dono if it has been covered yet,

but any nylon woven or twisted rope or cord will lose 10-40% of its strength when knotted.
the loss goes up with the diameter of the rope being used, and it will go down with the amount the rope or cord stretches.

break cord is very low stretch relative to its similar diameter OR similar strengh nylon. so a the same knot would weaken the break cord more than say, a suspension line.

sigh... i need to sleep. or cut my cast off.

[Faber 0]

People who SL shouldnt have a tight harness,that requires more than 80lbs to open i thing its half is like 40kg? am i right?
try do a pull test on your bridel whith a simple fishing weight.. my spectra loops aint loaded more than 3,5kg(at most)(if above is correct= 7lbs)to pop open the harness...

I however ALWAYS use a backupcord in case of premature break..

My harness is trimmed to be used at low frefeefalls thats why its so easy to pop open

NOTE: by using spectraloops and easy to pop harness,your in dangerzone if you take the same rig on a terminal(dunno why any would..).

Stay safe
Stefan Faber

[base689 0]

> re-reading your post, it seems you tried to break a loop of break cord and expected it to happen at 80lbs, it happens at 160lbs, because a loop is two strands together!
——————————————————————————————
Let's make it clear once for all.
A 80 lb - 36 kg break cord will break at 80 lb - 36 kg when "deployed" in a "perfect" environment such a laboratory with one single strand of break cord in the "jaws" of a dynamometer.
When we use break cord we are NOT in a laboratory and so we use it in a loop configuration, which loop configuration is going to break at 160 lb - 72 kg, again when measured in a laboratory environment, i.e., with a long loop with terminal ends sewn together in a long seam and same loop placed in the proper fitting of same dynamometer.
When we SL BASE jump, we do NOT have such a proper fitting, moreover we don't have up there a sewing machine, so, in the end, we do a surgeon knot in order to be able to close the loop and "surgeon knot" in order to minimize the "knot degradation factor".
Any cord/rope/whatever is going to have its own BL (Break Load) diminished every time a knot is done on it.
According to various books/text (Dan Poynter manual included), we can expect to have the BL diminished of 40% when a knot is done (or, new BL is 60% of thoretical BL).
So, given for granted the theoretical break load of our break cord is 160 lb - 72 kg (we are using it only in a loop configuration), in the end we come up with an actual BL of 0.6 x (160lb-72kg) = 96 lb - 43 kg.
To make short a long story: when we use a 80 lb - 36 kg of break cord in our SL BAS Ejump, we can expect that we break the loop of same break cord at 96 lb - 43 kg.
Or, said in another way, closing the loop with a knot "deteriorates" the break cord BL in a way that in the end we have a real BL which is nearly the same as the theoretical single strand BL (it should be double but returns to the "original" value because of the knot).

Stay safe out there
Blue Skies and Soft Walls
BASE #689 - base_689AT_NO_123_SPAMyahoo.com

[Ghetto 0]

I ran a test of paragear's 80lb break cord last night, and I'm still here. I will continue testing it until I find myself dead or hanging from an antenna by my bridle.

P.S. If you don't solve the mystery of the break cord, you could always resort to go-and-throws and/or higher objects

P.P.S. I agree with 980.

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