This time I sent Chris four samples to see what happens when you mix spectra and nylon runners. As before, the spectra runners were brand new Blue Water Titan runners rated at 27kN. The nylon runners were made from sections of a single piece of Supertape bought 8 years ago from REI. Past posts on rec.climbing indicated that the spectra sliced the nylon like a knife. Food for thought...

Sample #1. The first sample was just your standard Supertape nylon runner tied with a water knot. It failed at 14.9kN (3352 lbf). The knot broke. This was the baseline test.
Sample #2. The second sample consisted of a Supertape runner tied into the loop of a spectra runner. I thought this might be a viable alternative to the girth hitch because it requires no knot at all--the runners are joined as two interlocking loops.
Sample #3. The third sample was a spectra runner girth hitched to a nylon runner. This was the combination reported as dangerous.
Sample #4. The fourth sample was an attempt to strengthen the girth hitch by introducing a double loop for the nylon runner. The hypothesis was that the double loop increases the contact area and decreases the bending of the nylon webbing.

What happened? Well...the last three samples failed at:

• Sample #2: nylon Supertape broke at 10.3kN (2320 lbf) 69% baseline
• Sample #3: nylon Supertape broke at 13.9kN (3130 lbf) 93% baseline
• Sample #4: nylon Supertape broke at 14.7kN (3310 lbf) 99% baseline