Loop Shackles/Connectors aka The Nacrabiner

**oldgringo** · 03-28-2010, 08:57

Originally Posted by Frawg

Pardon me for not replying sooner; I was hoping one of the rope experts would have chimed in.

IMHO, the answer is 'yes and no'. On the yes side, just thinking about the physics of what happens when you bend a rope, I believe putting any rope through a tight bend will derate the rope. In fact, I suspect that's why knots weaken a rope. On the 'no' side, the 7/64 and larger HMPE lines we're using are so strong that even with the derating we aren't pushing the limit in most hammock suspension applications.

If I've got this wrong, I'm ready to be reeducated correctly.

I'm no expert, but I think there's more to this...pressure, friction, heat, to name three.

**Frawg** · 03-28-2010, 09:18

Originally Posted by oldgringo

I'm no expert, but I think there's more to this...pressure, friction, heat, to name three.

From stretching, squeezing and rubbing? IMHO these would be secondary effects, the way we're using these ropes. I don't think we think generate enough dynamic loading to make them significant compared to the tension, but that's just speculation. 'nuff said from this dummy.

**oldgringo** · 03-28-2010, 09:37

Originally Posted by Frawg

From stretching, squeezing and rubbing? IMHO these would be secondary effects, the way we're using these ropes. I don't think we think generate enough dynamic loading to make them significant compared to the tension, but that's just speculation. 'nuff said from this dummy.

Some have reported melting/glazing to Amsteel (or maybe that was straps? I disremember)...in any case, it left the impression with me that localized heating occurs where load (pressure) and movement (friction) come together in synthetics.

Dummy? Puh-leeeze.

**Just Jeff** · 03-28-2010, 09:42

If you pull a synthetic line across another synthetic line (or the webbing loop), the heat can actually burn thru the thinner one...I've cut rope this way before. This is a problem when pulling your hammock tight thru a tree hugger, especially if you have gear in it to weight it down. If it's not loaded and moving it isn't a big deal in my experience.

**Frawg** · 03-28-2010, 09:46

Originally Posted by oldgringo

Some have reported melting/glazing to Amsteel (or maybe that was straps? I disremember)...in any case, it left the impression with me that localized heating occurs where load (pressure) and movement (friction) come together in synthetics.

Dummy? Puh-leeeze.

Well, maybe not a dummy but I have more than my share of ignorance.

I'll bow to the voice of experience on this stuff.

Speaking of which, I had only one experience with friction heating of AmSteel (my only point of reference) and that was in my early experiments -- when I made a constrictor segment too short on a UCR, it slipped under load and both the constrictor and the internal line got pretty hot. I didn't see any damage to the line, but it did catch my attention.

Edit: just remembered that I did see some friction melting of the polyester Walmart webbing I used with my first Risk type hammock a few years back.

**oldgringo** · 03-28-2010, 09:47

I think that some movement is unavoidable when the hammock is in use (loaded), even in knots.

I don't think any of this dangerously compromises our suspensions, just making the point that I think radius of bend isn't the sole factor in the derating of cordage

**Frawg** · 03-28-2010, 09:53

Originally Posted by oldgringo

I think that some movement is unavoidable when the hammock is in use (loaded), even in knots.

I don't think any of this dangerously compromises our suspensions, just making the point that I think radius of bend isn't the sole factor in the derating of cordage

Point taken.

**Rug** · 03-28-2010, 11:12

There are two thoughts that are both wrong;
1) If it is old it must be good.
2) If it is new it must be better.

Dutch, your design is timeless. Its simplicity is its perfection. Nacrabiners have their place in the world (and in my gear-bag). But Dutchclips will always have a place on my tree-huggers.

Hammers and nails are thousands of years old. They did not stop being used because screws & screwdrivers were invented. Use the right tool for the job.

**lonetracker** · 03-28-2010, 17:28

new nacrabiner ideas. made a handle for the whipped cinch wind lock section.i used a nail knot(i think)with 4 loops.after this was tied i connected the leftover ends together as you would a continuous loop.you could also tie the ends together with an overhand knot.this handle is going to make it very easy to open and close this nacrabiner with cold fingers, in dark conditions,arthritus,ect.i call it the whipzip

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when i set up my hammock i have been hanging my suspension first and then attaching my hammock to it using a toggle.i am going to try replaceing my chain link/toggle system with a similar sized nacrabiner.

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