I love Opie's soft shackle pictoral (link below), and all his other pictorals too, but I got a question for you math weenies out there:
In opie's pictoral, he starts with 30 inches of Amsteel Blue (1/8" I think). When I made my soft shackle from Amsteel 7/64, it came out to 9.25" from adjustable loop to stopper knot. I think that's the circumference of the soft shackle, and I believe that you can use math (not my strong suit) to determine that the diameter is 2.944" (circumference/pi = diameter). This size is fine with me.
So I made a soft shackle out of Zing-it 2.2 mm using opie's instructions and it came out 10.25", or 3.26" diameter. That seems a little too big to me. So if I wanted a 2.2 mm Zing-It soft shackle, or even a 1.75 mm Zing-It soft shackle to be 2.944" diameter, how would the measurements for the instructions change?
In my simple mind, I'm thinking that one would use 90% of the measurements for 2.2 mm Zing-It. If you're using 30" of Amsteel Blue, then use 27" of 2.2 mm Zing-It. And reduce all other measurements in opie's pictoral by 10%. Does that sound right?
I would love to see this in a spreadsheet with some if/thens, but I ain't that smart. If you are using 7/64 Amsteel Blue, and you want a soft shackle 2.944" in diameter, then use 30" length and make a mark at 12" on one end and 2.5 on the other.
If you are using 2.2 mm Zing-It, and you want a soft shackle 2.944" in diameter, then use 27" length and make a mark at 10.8" on one end and at 2.25" on the other, etc.
I'm sure all this info is already on the forum in some form or another, but I loves me some spreadsheets. I could see a spreadsheet with tabs on soft shackle, soft shackle prusik, continuous loop, whoopie, etc. Enter your rope type and diameter, how long you want the device (or diameter), and Voila! Exact measurements for noobs like me who ain't too good at math.