Dan R Porter said:
I am also a rock climber and have done some heavy research on this subject. Understand that DannO has made MANY jumps on dyno Line, (Dynamic Rope, all DYNO ropes have different stretch %), So he was very scientific about his jumps, So this wasnt some shaggy set-up. His rig for this particular jump, his highest yet, had a variable overlooked that is OFTEN overlooked in all climbing, wether on the rocks or in the leaves...The stretch of the ropes (YEs his rig was not just 1 rope) stretch so drammatically and so quickly, that the ropes being twisted MELTED each other. at a thousand feet his ropes stretched hundreds of feet, so it was like two peices of sand paper rubbing together. With static ropes (Thats what rockers call our lines,) this is still possible if ran through a sling, or anything that provides friction, even a "Friction device" or a prussik can melt a rope. Be careful out there.
even on low rock climbing pitches, i have seen firsthand (2 deaths) what happens to climbing (or any synthetic rope for that matter) ropes that are subjected to high speed friction. Globs of melted rope, the size of golfballs and oranges, coated on the rappelling rack or other rappel device, and splattered on the ground beneath the climbing pitch. The friction (heat) buildup can be so high that the rope melts and the climber will actually rappel faster and faster uncontrolled, down to their death, due to the hot melted rope lubricating the rappell device. same as mentioned above, a rope running thru a sling or against another rope can heat up hotter than boiling water when placed under sudden load (tree trunk suddenly dropping...fyi) and then snap.
tis common practice amongst long drop rappellers to "cool" the rappel device with misted water while rappelling, to stave off
"friction (heat) induced lubricity causing death" (a term lifted from a coroners report here in BC, in regards to a rope related falling death) and to immediately remove the rappel device when on the ground to prevent the heat buildup from melting the rope (pull excess rope thru device while removing rapple device).
try rappelling 150' down smoothly and when on the bottom touch your rappel device - hot hot hot hot....more so with rappel/rescue racks, the large aluminum bars tend to retain heat build, they can get so hot it will brand your flesh. I use stainless steel bars in my rappel rack , they tend to run cooler. i also rappel slower adn smoother....
just to give you an idea of how heat stress can damage a rope:
take some synthetic rope, tie a piece around a tree limb and run another piece thru the first rope. grasp both ends of the second rope and saw back and forth. the second the rope breaks, touch where it broke you'll see glazed and melted rope, and it will be hot.
or
(this simulates the sudden loading of a rope (ie limb falling or tensioning a zipline with a truck)
tie a piece of rope to a solid anchor. tie the other end to your truck. have a helper reverse the truck quickly untilthe rope snaps. (be careful) immediately pick up the rope and feel where it broke. For about a foot in each direction the rope will be thinner, glazed and right near the break, the rope fiber ends will be black and hard, like when you take a match to nylon rope.
this can be applied to your arborist ropes as well, NOT just climbing, industrial, marine or rescue ropes.
(disclaimer: i am in no way responsible for your descision to try any of these tests. You are responsible for your own safety.) (just saying)
good post original poster
