Rigging a hammock with constrictor ropes (UCR's)...

[ZA206]

I found the information on this thread very interesting.

A few years back I did some extensive experiments in an attempt to use friction hitches for a Single Line Suspension, SLS, System. It worked, but only if I used 1/4" diameter rope for the main rope and 3 mm or less diameter rope for the friction hitches.

Since then I have been very interested in trying to find a friction hitch that would work or some other means to replace the friction hitch.

I read about your UCR above and thought immediately that the UCR arrangement might be adapted to replace the friction hitch on an SLS.

I have a Bridge more or less permanently hung on a hammock stand in the basement using an SLS using 3 mm AS-78 as the suspension system. AS-78 is Samson Ropes version of a dyneema using the newest SK-78 and coated with their proprietary Samthane coating. I really love this rope. I'm very cautious in what rope I use for my SLS and in making my Bridges. This stuff is really remarkable for it's strength and exceptionally light weight.

I immediately pulled out my Selma fid for 1/8" rope, picked up a length of 1/8" Amsteel Blue and spliced the AS-78 down a section of the Amsteel Blue. The splice buries the AS-78 down the middle of the Amsteel Blue. I was hoping to replace the bowline on the end of the SLS with the splice and a spliced eye. The splice would allow the Amsteel Blue to slide on the AS-78 and hence make an easily adjustable SLS.

Alas, it is not to be. The splice slipped as soon as I tried sitting down in the hammock. It did not hold even as good as the friction hitches.

I then tried replacing the Amsteel Blue with some 1/8" Vectran. Same results. I was tempted to try replacing the AS-78 with 2.8 mm Spyderline with it's very rough polyester sheath in the hopes of increasing the coefficient of friction and maybe having a chance of having the splice hold. But the thought of going back to sheathed Spyderline for any reason was enough to stop me.

The friction bearing surface on 3 mm diameter rope is just too small using either friction hitches or splices to hold the forces present. Now I have the Bridge set up with approximately a 28 degree sag angle at the tree. So the forces are not multiplied out of too much proportion.

I have a suspicion that if I went to 1/4" diameter rope throughout, the arrangement would work. I get the impression that ZA2056 used 1/4" diameter rope. Is this true?

In going from 1/8" diameter rope to 1/4" diameter rope the friction bearing surface is multiplied by a little over 3 (pi to be exact). However, I rejected the use of 1/4" diameter rope for the SLS a few years back in my investigations of friction hitches. The weight and bulk of rope both increase exponentially with rope diameter, hence they are just too much. The same reason I eventually quit using webbing in my suspension systems - too much weight and bulk compared to 3 mm rope.

Yes.... I use 1/4" Samson Tenex in my UCR's. I built some out of 3/8" Tenex, but they were too big (fat & heavy) for my original application. In my 1/4" UCR's with a half hitch lock, they don't move when used as a hammock suspension. I suspect the 7/64 stuff will not behave the same. I think a whoopie out of 7/64 would have a better chance of working in this application that the UCR arrangement.

-ZA

[ZA206]

Now I see... Thanks, Acer!

What threw me was that I've evolved to using a second toggle in place of the ring... my short term memory is turning to swiss cheese, I guess.

Chuck

Hey caboyer... make a whoopie out of the 7/64 and see if it works. You can experiment with the buried section length and see how it works.

How much of the amsteel 7/64 do you have? I'd swap you some 1/4" Tenex for some of it (or 3/8 Tenex if ya wanted).

-ZA

[Frawg]

Hey caboyer... make a whoopie out of the 7/64 and see if it works. You can experiment with the buried section length and see how it works.

Hi, ZA!

I'll give it a try. Anybody know where to find friction coefficients for any of these lines?

How much of the amsteel 7/64 do you have? I'd swap you some 1/4" Tenex for some of it (or 3/8 Tenex if ya wanted).

How much Tenex would the 10 inches of 7/64 Amsteel I have left get me?

Seriously, I just used the last few feet I had on this experiment. Not having proper fids, I found this stuff a real PITA to splice once it's been under tension, so I wouldn't wish that on you.

Best,
Chuck

[Frawg]

I managed to salvage a 7/64 Amsteel UCR to make a whoopie sling, which I tested as an adjustable ridge line with my toggled suspension. It held just fine under more tension than I'd ever want to use. The buried section was about 2 full fids long. I think this is how I'll do ridgelines from now on.

I'll try it on a suspension line next, as soon as I can pick through my leftovers to salvage a whoopie sling of suitable length. Based on TiredFeet's reference to the Amsteel recommendation, I'll probably make the buried portion at least 4 fids long, to begin with.

[ZA206]

I managed to salvage a 7/64 Amsteel UCR to make a whoopie sling, which I tested as an adjustable ridge line with my toggled suspension. It held just fine under more tension than I'd ever want to use. The buried section was about 2 full fids long. I think this is how I'll do ridgelines from now on.

I'll try it on a suspension line next, as soon as I can pick through my leftovers to salvage a whoopie sling of suitable length. Based on TiredFeet's reference to the Amsteel recommendation, I'll probably make the buried portion at least 4 fids long, to begin with.

I have a nice set of slema fids that I never use... I use a modified aluminum "standard solid" fid (not sure of the name) to make my UCR's. It makes life ALOT easier.

Post up some pictures of your whoopie conversion.

-ZA

[Frawg]

...
Post up some pictures of your whoopie conversion.

Here is a quick shot I just took of the salient part of the ridge line. I'll take a better one in daylight after I've made some more 'polished' slings.

I think I need to get some new line, though; I can't quite get the running end inside the old line I'm working with. Please bear in mind that I'm a rank amateur at this. I'm using make-do stuff for fids -- coat hanger wire, meat skewers, darning needles... (the local hobby shop was out of metal tubing small enough for the 7/64 line)

Chuck

[Frawg]

Success!!! (Thanks for the suggestions, Acer & SA!)

It ain't the purtiest piece of work, but it does work. Finally salvaged another 7/64 Amsteel blue sling to fabricate a whoopie sling for the suspension. Here's the results (overview, tree end, working parts, buried section*):



SA, the buried section* was about 3.5 fids long.

I was able to adjust the setup multiple times, with no slippage at all. I need to test it more over time but this looks very promising.

Thanks again for the ideas, guys!

Chuck

*update: found out the buried section is called a "brummel" <-- ERROR!!

**correction: see Nacra533's later post, in which he defines everything nicely.

[BaloO]

I wish I knew how to manufacture something like that...

Is there any guides out there on the very weird web?

[Frawg]

I wish I knew how to manufacture something like that...

Is there any guides out there on the very weird web?

Here's a video. The rest of the site is worth checking out, too.

The tail end of the video mentions a pdf file of instructions at Yalecordage.com.

HTH!

Chuck

[PuckerFactor]

I LOVE it Caboyer! Great work! I'll definitely do this with my 7/64" when it gets here and I make my hammock and tarp and... (you may notice I'm DIYing everything )

Acer