Sewn Amsteel Eye breaks at 85% full strength

When I first started working with Amsteel, I sewed, rather than spliced, eyes in the end. I never intended to use the eye on 1/8" Amsteel for more than a pull cord; I tested the eyes to 1400 lbs, without breaking them. Since a pull cord would probably never see more than body weight, I felt that was OK. My pull setup involved a crappy come-along, a 1100 lb-limit scale, and a mechanical-advantage system with a high-efficiency pulley; it was a pain to set this thing up. The other limit I had: my dominant hand is partly paralyzed, and splicing was, back then, very frustrating (until I got a D-Splicer).

So as time has gone by, and my break setup is a lot easier to use, I wondered how strong sewn eyes really were. There are times when you really do want to sew, rather than splice -- like when you can't afford 11" devoted to bury of a tapered tail.

The setup was the same as for many of my tests-- not a slow pull, but the force was provided by my jeep. I let the jeep roll downhill till the line was taut, then hit the gas slightly, for a break less than 2 sec after. One end of the Amsteel had a bury eye splice (loose sewing just to keep it from pulling out, should be full-strength), and the other end had the sewn loop. There was a short (1.5m) section of 10.2 mm dynamic rope inline to act as a force buffer.


The break was immediately at the end of the stitching, at 2120 lbs.  Given that the stitching covered just 1.5", this is a decent result.

For the stitching, I made a bight in the rope, and the two strands (out of the bight) were first sewn together in much the same way as here. After first sewing the two strands together with 300 lb bs UHMWPE braided fishing line, I slid a 1.5" section of 1/2" (1000 lb bs) tubular webbing over both strands, then stitched through the webbing and two Amsteel strands with a spiral pattern of more 300 lb thread, this time going through each strand perpendicular to the first set of stitches. At the end I saturated the nylon sheath with seam grip urethane. This loop was sewn 6 years ago, and I've since learned ways to increase the strength -- don't pull the stitches too tight, especially near the ends of the sewing.