Hanging from the Ridgeline

This has GOT to have been discussed here before, but I come and go and missed it I'm sure...I searched for it and missed there too...

SO...

One long rope or heavy spectra cord with two prussik loops attached...(allows for nearly all types of hammock ends to be used)...the rope allows for hanging from two anchor points WAY apart, the hammock is tensioned on the loops attached to the rope......as the hammock sags, the rope serves double duty as the Tarp ridgeline.....(weight will be an issue for the ultralighters / I understand that - maybe...How heavy would 25 to 30 feet of Spectra cord capable of safely supporting a hammock be?)

a link or two to prior discussions would be appreciated....

It may take a day or so for the Mathletes and/or "Quants" here to fully collect themselves for an in depth answer. I am not one of them, but I think it's a very (seemingly) simple and interesting concept though.

Good question.

I'll start in advance of the heavyweight mathletes.

It's an interesting idea, but I don't think your idea of Spectra/Dyneema load-bearing line with Prusiks is going to work. Most of those slide-and-grip hitches work based on a difference in diameter between the load line and the gripping line. Spectra's going to be thin, so I'm not sure you could get a Prusik to hold.

This part's just speculation: I wonder whether an integral Spectra ridgeline would have problems with shock-loading due to its extremely low stretch. Impact forces on a lot of hammocks are pretty small in part because their nylon supports stretch to minimize the peak load. At least in rock climbing, you don't ever want to fall onto a Spectra/Dyneema runner without some rope in the equation because it won't give at all, and will rip out.

The lack of stretch might be a good thing for the tarp, though, as it might correct some of the issues Hennessy hammocks have with getting a taut pitch. If it were possible to hang the hammock from the Prusiks using a higher-stretch material, that might take care of the shock-loading problem.

It's an interesting idea. Try it!

I'm not sure of the weight , but 25 to 30 feet of rope isn't going to span a great distance. obviously < 30ft. and I think I can span that with my Claytor JH (about 9 ft) and 12 ft straps on each side. So I guess I'm missing the point. What's the benefit??? Plus, the greater the span, either you have to climb the tree to attach the straps, or tighten the rope extremely tight to keep it from sagging. ( probably WAY unsafe IMO)

I am anything but a quant. But this sounds like the Single Line Suspension (SLS) which has been widely talked about and "peer reviewed" so to speak. Am I missing something?

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Originally Posted by Ramblinrev

I am anything but a quant. But this sounds like the Single Line Suspension (SLS) which has been widely talked about and "peer reviewed" so to speak. Am I missing something?

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I didn't go look. Have you got a link to it?

http://www.hammockforums.net/forum/s...ine+Suspension

As I looked at it again... the attachment is different in that there are no prussics used. I am not interested in trying this suspension so I don't know whether the same result is accomplished or not.

Again, I'm no mathlete or anything like that, but I don't think shock load comes in to play all that much. Dynamic ropes absorb/reduce the shock of a falling climber, but unless you are leaping into you hammock, I don't think dynamic lines are needed. I sit down nice and slow especially the first time..!!:)

Dynamic ropes absorb shock but they do so by stretching. In a static load system the weight will cause a dynmic line to stretch. If you have ever tried to haul a climber _up_ by climbing rope it is next to impossible because t=of the stretch factor. When I worked high ropes courses we could only let climbers _down_ on their ropes.

Quant? Did someone here call for a quant??? :cool:

adkpiper is right, for the idea as stated to work you need to have a single line from tree to tree whose diameter is at least 50% more than that of the line going from hammock to this cord. Waste of a lot of big diameter cord.

RamblinRev is right, this is the so-called Single Line Suspension. You can search on that and look for postings by headchange4u, and TeeDee.

If I understand TeeDee's method correctly, you replace the prussiks in the method you propose with Marlinspike hitches that hold a toggle in place, then hang the hammock lines from the toggles. I do Marlinspike hitches at the trees all the time, takes all of about 3 seconds.

This way you can use a thin strong line between trees, which makes much more sense than a fat one.

dang, no equations. Well, maybe next time...

Grizz

Might be interesting to try with a warbonnet style whipped hammock. Just run the line thru the whippings with knots on the inside of whipping tied at desired RL length, then tie-off. Might be worth a go. :unsure:

For what it's worth, the 50% rule for prussik knots isn't all that accurate. It all depends on the type of cord. I've successfully used a purcell prussik, which is an ascending system comprised of a bit of cord tied back onto itself with a prussik knot for adjustability. This thing holds well enough to use as an adjustable anchor point for rock climbing, and it's basically a prussik attached to cord of the same size.

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Originally Posted by Mustardman

For what it's worth, the 50% rule for prussik knots isn't all that accurate. It all depends on the type of cord . I've successfully used a purcell prussik, which is an ascending system comprised of a bit of cord tied back onto itself with a prussik knot for adjustability. This thing holds well enough to use as an adjustable anchor point for rock climbing, and it's basically a prussik attached to cord of the same size.

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yeah, no kidding. I've been doing some stuff with very slippery cord used in sailing, and knots I'd always thought to be non-slip and "safe" actually slip. But then sheathed cord that offers a lot of resistance would I think not only work, but may work with smaller diameter, and / or more complex hitches such as you suggest.

Grizz

I just realized that this single line prusik system is not as foriegn to me as I thought.... I was trying to wrap my little brain around the exact suspension I've been using on my tarp for months!!! :lol: It sure works great for that application as the tarp can be adjusted up/down the ridge line, and it also makes it easy to leave just enough sag in the section of ridgeline under the tarp that it doesn't wear the tarp. I have two more prusik loops that I leave attached to this saggy ridgeline to clip my bugnet to. I then slide those if the net is hanging loosely.

This support system should work for a hammock. It just depends on the rope used.

IF you were trying to use a SLS then would it not make sense to use cordage tthat was about twice as strong as you would normally use in order to lessen the stretch? so using the thick dyneema cord would be better?

Thanks for not slamming this from the git go....the 25 to 30 foot length was an arbitrary length used for example...Idea is; you can substitute a rope/cord (Of whatever diameter) for the straps and hammock suspension ropes, and gain because you then have the ability to span a much larger distance between tie outs than before, with the same ability to pitch a ridgeline tarp......AND you can also decide to move the whole setup to one end of the suspension line or the other, or anywhere in between....

The biggest and most frequent problem with hanging I've faced is finding a place to hang when the tieout points are to far apart to be useable...everything else I seem to have a handle on.....

It may have been done before, but I'm going to work on this idea....seems I remember a technique I used in the military for single rope suspension bridges refered to way back then as a transport tightening system....should work to tension a hammock suspension line.....

Again, thanks for all the feedback!

Well, be sure to post your results, now that you've gotten us all interested. :p

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Originally Posted by SuperTroll

......AND you can also decide to move the whole setup to one end of the suspension line or the other, or anywhere in between....

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with a really long span you might have some surprises in store when you shoved the hammock all the way to one end or another. Nothing that changing the height of the attachment point on a tree couldn't deal with, but you might need a lightweight backpacker's titanium step-ladder...funny things happen when you go off center...

Grizz

Funny strange, or funny "ha ha"?

I cerrainly think this system can work. And I often do carry long lengths of rope. ( mostly a 'just in case' thing. I rarely if ever use anywhere near all the cordage I bring. Maybe with more experience I'll find just how much I really need and will leave the rest at home.)

I like the idea of being able to easily adjust things and having a ridgeline...and having a long length of cord if needed :rolleyes: ,but I like the easy of ring buckles/ straps so I can just throw the ends around the tree and clip with the carabiner. I think I can put my hammock, net, and tarp in less than one minute! Thought that it not at all necessary. I'd probably be better off to have something lighter and less bulky. Doubt I'll switch for a while though.

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Originally Posted by NCPatrick

Funny strange, or funny "ha ha"?

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funny == unanticipated

positioned in the center your hammock will be more-or-less level. For the same level tree-to-tree line, shove the hammock well off center, and when you get in the foot and head ends will no longer be at the same level.

You'll want to make the height correction on the tree closest to the hammock, because there you have the greatest impact on raising or lowering the hammock end closest to it, as a function of how much you raise or lower the connection to the tree.

Grizz

I use un-sheathed spectra cord*, & NOTHING I tie to it will hold a prussik. The knots at each end (for the ring buckles) are figure 8s with a "safety hitch" & have held well for 2 years, but try as I may I cant get a prussik to hold even a little bit. Well, nylon accesory cord holds about 5 - 10 Lbs force, but only if I cinch the knot down very very tightly before pulling on it, once I release the pressure of pulling, the knot relaxes &, , , , if I was hanging from it, I would be a groundling rather quickly.


* Spectra is way slippery!

Quote:

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Originally Posted by SuperTroll

This has GOT to have been discussed here before, but I come and go and missed it I'm sure...I searched for it and missed there too...

SO...

One long rope or heavy spectra cord with two prussik loops attached...(allows for nearly all types of hammock ends to be used)...the rope allows for hanging from two anchor points WAY apart, the hammock is tensioned on the loops attached to the rope......as the hammock sags, the rope serves double duty as the Tarp ridgeline.....(weight will be an issue for the ultralighters / I understand that - maybe...How heavy would 25 to 30 feet of Spectra cord capable of safely supporting a hammock be?)

a link or two to prior discussions would be appreciated....

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Not to discourage you or anything, but .... :laugh:

I hang my tarp from a ridge line using Prussiks. Makes it easily adjustable. So in my constant search for easier and simpler, like you, one day in the distant past (more than 12 months back), I thought why not do the same thing with my hammock - hang the line tree-to-tree, 2 Prussiks, and hang the hammock from the Prussiks.


So I took some 2.8 mm (approximately 1/8") diameter Spyderline for the tree-to-tree line and used more 2.8 mm Spyderline for the 2 Prussik loops. I know, I know, same diameter, but since this isn't a climbing application, I thought it might work.

Used the Spyderline because of the polyester sheath over the dyneema core.

Strung the line, hung the hammock from the Prussiks, slid the Prussiks to adjust and thought "this is great".

Slowly and gingerly sat on the hammock, then slowly and gingerly swung my legs aboard and slowly and gingerly laid down.

Ahhh - I like this.

Then I shifted my weight.

Heard this horrible screeching noise and simultaneously dropped a few gut clenching inches. :scared:

Slowly and gingerly I swung my legs out of the hammock and slowly stood up and started breathing again when my weight was free of the hammock.

Checked the line and Prussiks. The foot end Prussik had slipped and slid about 3" to 4". The polyester sheath where the Prussik had slipped was smooth as glass and quite warm to the touch. Not the usual rough exterior. Tried to slide the Prussik back to it's original position. I couldn't budge it.

Unhooked the hammock and tried to untie the Prussik that had slipped. Very difficult to untie. The heat caused by the sliding Prussic had literally melted the polyester sheath of the tree-to-tree line and the Prussik cord and melted the two lines together.

I then took another line, 1/4" diameter, polyester sheathed dyneema core line and used that for the tree-to-tree line and the 2.8 mm Spyderline for the Prussiks.

That combination worked very well. Got in the hammock and vigorously bounced around. No slippage. The Prussiks adjusted easily and held very well.

Then I held that 1/4" diameter line coiled in my hand and decided that for car camping it would make an excellent suspension system. But for backpacking - way too heavy and the bulk of the required length left little room for anything else. The 1/4" diameter line is even more bulky than webbing.

So - conclusion: when using a method of transport in which the bulk and weight of the 1/4" diameter line isn't much of a consideration, the Prussiks on a line is an excellent means for hanging the hammock.

I have been playing with Tee-Dees, HeadChange4U, et al Single Line Suspension after reading ALL of the threads and Tee-Dee's extensive tutorial. The crux of the matter for me is after you tie the single line tree to tree then how do you center the hammock on that line. Although a Prussic attachment would be ideal if it worked, Tee-Dee's experience and others are not encouraging. However- in Tee-Dee's early write up, HERE, he used a Larks Head to the single line (instead of a prussic ) with a Marlin Spike stopper knot in front of it to keep the Larks Head from slipping. I think if I use a Prussic instead of a Larks Head I can easily slide the hammock along the SLS to center then quickly put in a Marlin Spike stopper.

Tee-Dee moved on from this early method and simplified his approach, but I seem to drag my hammock along the ground a lot when using his latter method of attaching the hammock directly to the Marlin Spike stopper knot. So I am going to give the Prussic with stopper knot a try.

-SlowBro

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Originally Posted by Doctari

I use un-sheathed spectra cord*, & NOTHING I tie to it will hold a prussik.
* Spectra is way slippery!

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I tried a prussik out of 2mm Marlow 100% polyester on 3mm Amsteel Blue (yes, I realize now that the line sizes were no doubt too similar) to suspend my little 'solitaire' maglite. The light just slid right down to the low point of the ridgeline.
It was kind of fun, lying there batting the flashlight up and down the ridgeline.
"Whack" up goes the light
"Whee" slides down into reach again
"Whack"
"Whee"
you get the drift ...

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Originally Posted by SlowBro

The crux of the matter for me is after you tie the single line tree to tree then how do you center the hammock on that line.

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I don't recall exactly how TeeDee does it, but if you have two fixed attachment points for the hammock on your line, getting them centered is no problem. I lash one end to one tree, take the line to the other tree and keep that point on the line pinched between my fingers. Then, I go back to the first tree and compare the length from the first attachment point to the first tree with the length from the second attachment point to the point I kept pinched. I even out the lengths and tie bowlines (after first adjusting the lengths to get the right sag angle). It takes longer to describe than to do...

today was my first try at using the single line suspension - did OK so long as I stuck to what TeeDee had described but then I wanted to tweak the length of the line slightly and discovered something Not To DO : I had a fairly long loop at each end of the support line hooked onto the stick at the tree hugger marlingspike hitch so I thought I would just throw a couple loops around each end of the sticks to shorten the line slightly - this proved to be a Bad Idea - the extra loops moved the force from the hammock out from the center attachment point and as a result the sticks broke dumping me on the ground (twice) - no damage just a somewhat muddy hammock - I had made sure there weren't any rocks under me before trying the SLS

another item learned - I need to be more careful in how the bowline knot is drawn up - one of mine had a small blight from one part of the knot under a different part of the knot and as a result it was rather difficult to untie in the 2.8 spyderline

Oh well lessons learned the hard way stick better.