Force calculation for a unusual hang

[redhawktx]

"The second pic is a diagram of an anchor system I have used with success. It is based on a continuous loop of Amsteel, 12-15' total circumference and three long stakes. Arranged in three loops and run through a carabiner it self-adjusts so that the force is distributed equally on each stake"

Go this quoted route. I have constructed a hammock stand with bipods as in the pictures with the jeep. The first time I tried to lay down in it (gently!) One of my plastic stakes holding the guy lines from the bipods broke in half underground, launched itself towards me, and implanted itself partway in my thigh. After much cursing and basic first aide I replaced the single stakes in the ground with three stakes connected by a continuous loop as illustrated earlier in this thread (not the in-line method). I have had no problem since.

I haven't done the math on this either, but I can tell you from practical experience that the pulling force on your guy lines is several times your own body weight.

I will be bringing my setup to the Ozark Hang in March if anyone wants to see it. It cost me about 20 bucks total to construct. Close-out on hardwood 2X2 tall planter stakes for the bipods, 2 eye bolts with washers and nuts, 12 stakes, and whatever line I had laying around. The close-out planter stakes even came pre-drilled so all I had to do was measure and cut line.

Make sure you have some way of keeping the feet on each bipod from splaying out to a 180degree angle. From your pictures it looks like you are relying on the tightness of the eyebolt to keep them from splaying. That and the friction of the feet on the ground. At some point this combination will fail and you will go from hanging comfortably in the air to landing painfully on the ground. This, again, is painful experience speaking.

[BBQDad]

WRT Spanish Windlass: For clear pictures and a description of operation with some tips for use see:

http://www.inquiry.net/OUTDOOR/skills/b-p/windlass.htmhttp://www.inquiry.net/OUTDOOR/skills/b-p/windlass.htm

On p. 306, "The Ashley Book Of Knots" (written by Clifford W. Ashley and sometimes referred to as the "CWABOK") depicts and describes the multi-stake method shown by GrizzlyAdams---see Knots #1819 and #1820.

See p. 328-9, Knots #2020 through 2026, for various riggings including the Spanish Windlass.

See p. 334, Knot #2065, for a depiction and description of the Chinese or Differential Windlass.

[james90755]

So here is the conclusion to my work... the anchor is three 9" screw stakes and a 13' continuous loop. The ground is very soft, so it took three. I expect most ground I will see on the Jeep trails will be harder and thus two stakes needed. I like the two stake idea based on a lesson I learned while testing the rig.

During the two stake test, one pulled out. After I hit the ground, I had a flash that the bipod might be coming don on me. When I looked up, the other stake held the bipod enough to keep it off me. I think I dodged a bullet; I imagine a bipod to the head would hurt.

Some pics of the finale:

[MaxM]

I was wondering if you tried using the bipod as stakes, or if you tried incorporating any angles in them other than perpendicular to the ground.

Something like either of these??

hammockstand.jpg

I am by no means as good at math and calculation as all of you, but I would like to try a project like this and was wondering just as much for my own benefit whether these would be viable options. Mine wouldn't have to be quite so mobile.

[NickJ]

Why not use the winch? take a standard 4x4 ground anchor and pull out the winch cable. run a shackle through the eye of the ground anchor and put a pulley block onto it. Run the cable through the pulley block and up over your rear A frame (you could also use a pulley block there too to reduce the pressure on the cable) then route the cable back across the top of the other A frame and secure the winch hook to one of the recovery points on the front of the vehicle. Then all you need to do is have a simple arrangement to keep the A frames vertical which shouldnt be hard at all.

This won't work on rocky ground ground though, but if there are other vehicles there you just use one of their recovery points with a pulley block and get the same effect.

[james90755]

I thought about the winch... but its a crude device... but very strong. I agree that using the Jeep is a good idea, but it does take the Jeep out of commission when supporting the hammock. I was looking for a more stand alone design. In reality, I think the Jeep will be used as one anchor point, possibly two hammocks coming off the front bumper's tow points. You know the sig-other will want one once she she's it.

The ideas are still flowing... I have another idea that is way simpler, but it requires welding. Think along the lines of a hammock stand where the middle piece is the front bumper.

I will post up when I get the idea fabricated...

[Tinkerman]

I have used a setup like you have sketched. I used 1" metal electrical conduit to make my uprights &capped the ends with the rubber end caps from home Depot You have indicated 50" for length? I first used 60" (half the length of the conduit) &found that really wasn't as long as I wanted. I now use 2 40" sections spliced with conduit connectors. I also have an upward extension to hold a tarp.
It sets up easily & has worked well,so far. I'll be probably be setting it up at the Ozark hang this weekend. I'll try to take pictures if you are I retested in seeing them.
I developed mine for river camping on the Ozark gravel bars & usually can find a root or even a small tree to tie to. This weekend I will probably be using a big ground auger. I'll try to get a shot of that too.

[james90755]

I have used a setup like you have sketched. I used 1" metal electrical conduit to make my uprights &capped the ends with the rubber end caps from home Depot You have indicated 50" for length? I first used 60" (half the length of the conduit) &found that really wasn't as long as I wanted. I now use 2 40" sections spliced with conduit connectors. I also have an upward extension to hold a tarp.
It sets up easily & has worked well,so far. I'll be probably be setting it up at the Ozark hang this weekend. I'll try to take pictures if you are I retested in seeing them.
I developed mine for river camping on the Ozark gravel bars & usually can find a root or even a small tree to tie to. This weekend I will probably be using a big ground auger. I'll try to get a shot of that too.

In the end, I put 3/4" square tube inside the 1" and use lynch pins to create an adjustable length of either 60" or 72". Its working good.

I do worry a little about a catastrophic failure that brings the bipod down on my head...

[LazyDaze]

I tried a ridgepole of chainlink fence top rail on a similar (tho non-portable back yard) hang, and it just bent! It was 16'6" between the verticle supports which are 3/16" wall thickness x 8' terminal posts 2' into the ground. I filled the verticles with a rebar and cement. Works great for me in my HH, BUT they flex a bit when I hang my two person hammy. I'm thinking of sinking an anchor chain 2' into the ground with rebar running perpendicularly through a couple of the links and some amsteel blue from verticles to anchors.....