Rope grab recommendations for rigging

I see the continuum as worst concentrated force load on small heavy concentrations toothed devices, not as bad concentration on more pointed small radius contact cams/pinches, then longer/gentler smooth face cammed contact, and best the full rope surface spread of friction hitch contact. By full surface I mean vs pinch from 180 deg opposing sides of the rope, instead from all 360 deg directions squeezing the rope.

Brocky, I think petzl is a fan of putting the rope through a bent path in all those devices. They seem to have a wrap plus pinch approach.

edit fix order!
 
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I made half hearted progress trying to find hitch pull testing so far. But, I did find drop testing where a short drop of 185 lbs caused serious knot tightening and some glaze damage to the rope. So far, a lesson is don't shock load slip your prussic because you can get heat damage. To me this has implications to setup to avoid eg catches of a spar on a prussic. Maybe a bollard instead spreads out the hit or can be configured to not slip. 185 lbs in a small drop wasn't very much but it caused some damage. In note, there was no spike absorption and dropped/anchored on a huge leader/branch with no give.
 
I've had a prusik slip multiple times from guys pulling on fiddle blocks attached to pull lines. The prusik melts to the line, they end up welded together. That would be a fun test with a load cell, see how much pull it takes to do that.
 
In 2002 a Narc :) provided information:


The helical knot looks like a VT with one braid over vs under or vice versa.
Suislide made it into the report! When a guy said that phrase to me many years ago I thought he was just a joker!

I've read half of the report and boy does it hit the nail on the head. Ask and ye shall receive. The DRT test results can be back characterised by measuring the tension ratio for the safety blue going through two "rings" (maillons?) as a substitute for a tree crotch or friction saver and the presumption is that the hitch would settle more than the other rope leg resulting in direction of rope travel over the rings that places the lower rope leg tension on the hitch side.
The SRT tests were canopy tied configuration not base tied. This matches a likely pull line configuration.

The raw data is great. Some of the analysis, well, saying ropes welding together helps stop you - when the rope goes gooey it's actually a lubricant IMO.
 
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In the results tables of the report there's notes. In the single rope pull tests after slippage they noted a much lower hold force after the onset of slippage. This suggests a possible run-away condition in a real world overload slippage failure. Worth noting IMO.
 
I found a couple older references to a "Bluewater VT" which was actually just a hollowbraid technora eye to eye, mis-named, supposedly intended to tie new fangled VT hitches with. Hownot2 did a pull test where because the hitch was technora, it didn't melt, but the host line suffered. They could smell the hot plastic.
edit - correction, they show the pamphlet, it has a nylon core.


co-video goes with it, og product guy

Don't remember this camera view - smoke!!!


more heated rope and some saddle stuff
 
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