Girth-Hitched Eye Splice Breaks at 77% on Carabiner,  100% on 1.75"+ pipe

I normally carry 2500 lb (1/8”) Amsteel Dyneema slings with spliced eyes in each end. Sometimes, to get enough length, I must girth hitch a sling through the spliced eye. This made me a little nervous, as I wasn’t sure how much the girth hitch would weaken the attachment below the 2500 lb quoted breaking strength. I have break-tested 1/8" Amsteel between eye-to-eye bury splices many times, and it typical breaks near the average quoted strength of 2500 lbs, in a moderate-speed pull behind my jeep.

1) Worst case: tight on I-beam carabiner. This simple test used a somewhat old sling with Brummel eye splices on each end. One eye was girth-hitched around an Attache carabiner; the other eye was looped over a nylon-sheathed 6mm Dyneema soft shackle. The sling was pulled to breaking by my jeep (with a linescale 3 load cell in-line). The set-up:

Breaking was at 1934 lbs, or roughly 77% of full strength. This was “worst-case” test, as I normally would girth-hitch around a larger object. The eye on the carabiner broke in the Brummel; 6 strands were on each side of the break, so the Brummel was made correctly.

2)  1.75"+ pipe. I did 3 replicates with Amsteel spliced eye-to-eye with bury splices. The Amsteel was new and all from the same batch. Most of the set-up was exactly as above, except the jeep-side attachment was to 1.75" OD steel pipe (the outside of which was wrapped in 5 layers of gorrila tape, as shown below), and a thicker nylon buffer line with sewn loop terminations.

This was an attempt to simulate girth hitches on the small trees I may use as anchors. Again I pulled to breaking behind my Jeep; in one trial I accelerated in one step, over about 1.4 seconds to breaking. In the other 2 tests, I accelerated till I could feel the nylon buffer rope tauten, and held the position for ~2 seconds; then I hit the gas and broke the sling. The average breaking strength for the 3 tests was 2592 lbs, slightly above the reported average strength of 1/8" Amsteel Blue between bury eye splices. I wish I could test the breaking strength of a 2" tree anchor!