Treeless Suspension

[digrat]

Last October, I went camping with Cub Scouts. My two sons slept in the tent, but I wanted to hang. Unfortunately, we were in the middle of a field and the only trees were 40' or so apart.

So I pulled out 6 staves (old broom handles) and lashed two tripods together. I knew that I'd need to pull the suspension lines tight since my ends would be only about 5' off the ground, and I didn't want to end with my behind on the ground. I also knew that I'd need to back up my stakes with more stakes, in a similar fashion as you'd anchor a "monkey bridge."

I'm ashamed to say that I didn't get a photo of my rig, but I did make a diagram:



I also posted more details on my blog: http://digrat.blogspot.com/2008/10/h...ingenuity.html

[Rushthezeppelin]

A few people have actually been able to get away with a bipod with no stake reinforcements (although I think most used tow guylines out instead of one). Not bad for car camping but it seems we have yet to find a system you could really reliably backpack with.

[pedro]

A few people have actually been able to get away with a bipod with no stake reinforcements (although I think most used tow guylines out instead of one). Not bad for car camping but it seems we have yet to find a system you could really reliably backpack with.

On the contrary, if you search on "treeless hang" you will see a couple of very backpackable options. I've hung from ski poles, and from an aluminum folding crutch. All that was needed in this situation was a bipod.


BTW Digrat: Nice adaptation, man! What kind of stakes were you using?

[warbonnetguy]

yes, i've done a bipod (rather than the diagramed tri-pod) made out of scavenged deadwood.

[Shug]

Here is a semi-treeless hang I did at a bluegrass festival. Big circus tent stakes in the ground since I was car-camping.
It worked well.
Shug
tarp.jpg

[HitchHiking]

Very Nice Hang Shug,
some sturdy telescopic aluminium poles ,might do the trick if the join was ridgid enough.

[MacEntyre]

...some sturdy telescopic aluminium poles ,might do the trick if the join was ridgid enough.

I've been working on just that. The problem is that telescopic aluminium poles are heavy, and expensive... like $50 each!

You can hang normally from a point seven feet above the ground if you shorten up your suspension. I hung this weekend from hooks that are positioned for a Pawley's Island hammock at a beach cottage, just dropped my double rings right onto the hooks. Had to scandalize the ends of the tarp, but it worked just fine, no worries!

I have two light weight, seven foot aluminum poles that I want to try with one pole on each end, three guy lines on each pole, and a tarp ridge line between the poles. Before I do that, I've been looking for a reference that might indicate the static load bearing strength of the poles. If they are marginally capable, I might reinforce them with fiberglass first.

[Frawg]

I got curious and had to try this out. Found some aluminum crutches in a closet here and decided to try a "treeless" hang. Didn't have any heavy duty ground stakes, so I improvised with some oversized "stakes" on hand -- a tree and a porch column. The lashup supported my 195 lb weight successfully, although I'm not sure I'd try to hang overnight this way.

What became immediately obvious is the need to adequately secure the guy line(s) and the hammock connection to the top of the post (crutch). The aluminum was too slippery for the large rope I used to grip adequately.

The first pics show the guy line tied off approximately horizontally to the "stake", while the last ones show the guy line angled downward, more like a single ground stake setup.



BTW -- In the "taking a sledgehammer to a fly" department, I found a reference on "Buckling of Circular Cylindrical Shells".

[MacEntyre]

I found a reference on "Buckling of Circular Cylindrical Shells".

Thanks, but I have no interest in derivations. I was hoping to find tabular data.

[Frawg]

Thanks, but I have no interest in derivations. I was hoping to find tabular data.

I found a table showing tensile and yield strengths for aluminum tubing of various types. I'm not an ME, but I think you could use those numbers and the cross sectional area of your tubing (OD area - ID area) to guesstimate the force your tubing could handle.

Edit: Looks like it's a tad more complicated... Couldn't find any simple tables, but this paper talks about column buckling design and gives a formula by way of illustrative example. Gotta run at the moment, but I can try some calculations for you later if that would be helpful. I'd rather defer to an M.E., though.

Chuck