Toggled Suspension System

[Frawg]

Tonight I posted a detailed tutorial "Whoopie Sling Mod to WBBB" on making a whoopie sling out of the AmSteel suspension line on my hammock. This will work for any woven hollow core high tech line.

That was a great job, SloBro!!

... and I had one episode of slippage with the URC when I forgot to tighten it up properly.

I think I posted somewhere in all of this that I'd done a quick experiment with the UCR, leaving only about two or three inches of the constrictor section tightened with the remainder left loose. I then sat in the hammock. There was an initial slip, but then the remainder of the constriction section gripped -- not all the way to the end, but I think I now know why* -- and held firm. I've never had my UCRs land me on my bum, and never had one slip after being set. I think both slings and UCRs are both great, but I'm not particularly concerned about slippage with either of them. I now believe that the securing hitch I used on the loose end (I now use a rolling hitch instead of the slippery half hitch) is the UCR analog of the lock in a locked brummel -- it keeps things from working loose under light loading. (IMHO... I'm no expert on rigging)

* Re the loose end of the UCR's bury -- I need to think about the physics of this some more but, after a little head scratching, I convinced myself that the static friction is distributed as a decreasing exponential along the lenth of the constrictor section. Given a long enough section, for a given line load, the 'loose' end of the constrictor feels hardly any force; it's not gripping, because it's not induced to. Add enough load, and more of the constrictor comes into play. Add too much load, and the entire constrictor will be insufficient to hold.

Cheers!
- Chuck

[SlowBro]

That was a great job, SloBro!!

I think I posted somewhere in all of this that I'd done a quick experiment with the UCR, leaving only about two or three inches of the constrictor section tightened with the remainder left loose. I then sat in the hammock. There was an initial slip, but then the remainder of the constriction section gripped -- not all the way to the end, but I think I now know why* -- and held firm. I've never had my UCRs land me on my bum, and never had one slip after being set. I think both slings and UCRs are both great, but I'm not particularly concerned about slippage with either of them. I now believe that the securing hitch I used on the loose end (I now use a rolling hitch instead of the slippery half hitch) is the UCR analog of the lock in a locked brummel -- it keeps things from working loose under light loading. (IMHO... I'm no expert on rigging)

* Re the loose end of the UCR's bury -- I need to think about the physics of this some more but, after a little head scratching, I convinced myself that the static friction is distributed as a decreasing exponential along the lenth of the constrictor section. Given a long enough section, for a given line load, the 'loose' end of the constrictor feels hardly any force; it's not gripping, because it's not induced to. Add enough load, and more of the constrictor comes into play. Add too much load, and the entire constrictor will be insufficient to hold.

Cheers!
- Chuck

Thanks. I made separate UCRs with 6+ fids of bury and a tail long enough for a slippery halfhitch (which, IMHO, never seems to grip very well around the hammock line. I'll have to try a rolling hitch) I toggled to the tree and toggled to the hammock. I spent one night out using one at each end and they held fine. I made sure to milk them down sung on line before climbing in.

Then I decided to try out a whoopie sling and incorporated it into the line coming from the hammock. I tried one of each, a whoopie and UCR, one at each end. That worked fine except for one time when I made an adjustment and then sat down. The UCR end started to slip verrrrry sloooowly then it grabbed. (like your earlier experiment). I realized that I hadn't milked it tight after the last adjustment.

I like the idea of the UCRs. Basically it's like a directional prusik that can be slid along any length of rope to the point needed. The whoopie is very much limited in comparison. However for me the whoopie is a little less finicky, and since I'm using it in this case for my hammock lines I don't need a loop over about 5' so the whoopie can work. For longer spans the UCR would definitely be preferable to me.

Anyway, thanks for all the experimental work you did and posted. It really helped me to see the light

-SlowBro

[Frawg]

Hey, SloBro -- it's all good, man! I like what you're doing.

For my part, I'm just happy that either approach works with those tiny lines. It took me a week before I could get used to trusting them to hold my full weight.

I'm kinda like TeeDee, now -- happy to have found my 'final' answer.

Cheers!
Chuck