Better than UCR? Less cord than whoopie slings? More trouble than it's worth? A new design.
I've devised an(other) alternative to the UCR or whoopie sling which may or may not be an improvement on either design. In my opinion, it improves upon each in some way.
Whoopie slings:
- Easy to adjust
- No concern for slipping
- Uses lots of cord for a given max length
UCRs:
- Uses less cord than whoopies for a given length
- Can slip if not fully "milked" or if not backed up properly
- Has a loose tail that can slip out of the constrictor
New design:
- Uses marginally more cord than a UCR, much less than a whoopie sling
- Slightly longer minimum length
- No free ends that can be lost into the constrictor or become unbraided
- Relatively secure; no need for extreme care in 'setting' adjustments
- Somewhat more complex construction, can still be made in less than 10 minutes and easy to understand
This design actually arose from a misunderstanding about the construction of whoopie slings; I had initially thought that the constrictor was loaded on one end only, and that it was formed by the free side of the loop end. Fortunately, I realized my mistake after a bit more thought, but I was left pondering the idea of an adjustable sling that wouldn't need as much cord as a whoopie and wouldn't be as fiddly as a UCR (which I had not heard of when I started in on this). In the end, I came up with something that's a bit of a combination of the two. This sling has a fixed eye at one end and an adjustable loop at the other end, but in between there is not one, but two constrictors. The first can change the size of the adjustable loop, and the second can change the length of the end with the fixed eye. The two constrictors are both on the "sliding side" of the loop, and are arranged such that the first is stabilized by the second, while the second is stabilized by a Prusik knot similar to that used in a UCR. Unlike other slings, which have a third free end hanging out of a constrictor, this design has a free loop in the middle, which cannot escape the constrictors and come apart due to a careless adjustment or slippage.
INSTRUCTIONS:
- Cut your cord to length; by my estimate you should add three feet to your target length*.
- Start by splicing a 4-inch loop in one end, using a short bury (I used a bury length of about 3.5 inches). Make reference marks at 4 inches and 12 inches from the end. I recommend a locked Brummel splice. Tapering can be done after pulling the splice, before "milking" the end in, by cutting the tail at an angle. I use the angle of the braid as a guide. Use a razor or other sharp edge to get clean cuts.
- Make a mark at the end of your bury, leaving enough room for the taper. Mark the following intervals after: 6 inches, 1/2 inch, 6 inches.
- Splice the free end of the sling through each of the 6-inch sections starting at the last mark to create the sliding loop.
- Use the fixed eye to form a Prusik knot around the free end. Two turns is sufficient; this knot only keeps the constrictor from slipping, and does not need to bear the full load.
- Splice another loop in the other end using a bury at least 5 inches long. The loop can be as short as two inches (finished length, 4 inches raw) if using small hardware such as whoopie hooks. If using a marlinspike suspension with your tree straps, a longer loop is recommended in order to keep the leg angle small.
Adjustment can be made simply by pulling on the free cord between the constrictors to form a hanging loop.
I've measured a pair of 10-foot slings at less than 40g with a total cord usage of about 26 feet.
If there's interest, I can put together a video to explain how they work, but it's pretty straightforward.
*All measurements are based on construction using 7/64th inch Amsteel Blue.
20160327_120611[1].jpg
Reply With Quote
Bookmarks