Ridgeline Question

[fifty2eighty]

I tried a ridgeline with an amsteel whoopee sling I made on my ENO DN a few months ago, but it twanged and felt extremely tight. So I shelved it for the time being because I just wasn't sure if I did it right. Lately I have been thinking about it because I want to reattach it for the ENO bug net I just received.


I'm not very good at physics but my assumption was that the farther apart the trees are the more weight gets transferred across the ridgeline. The only other way to alleviate the weight distribution would be to put the tree straps farther up on the tree. But when you are vertically challenged like me (5'7") there's only so high one can reach.

Since I'm thinking that the length of the ridge line should always be x inches to achieve 30°, should I be concerned about the weight distribution across the ridgeline or is there something that I haven't discovered on the forum that might help my setup?

Thanks in advance,

Dave

[zukiguy]

The "twang" is fine. Mine turns my whole hammock into a nice bass drum if I strum it.

The ridgeline is there to do exactly what you're asking it for, keep your hammock the same shape regardless of how you hang it. So you can pull the hammock tight and tie it low on the trees or hang it high to get close to a 30 degree. Either way the shape and lay of the hammock should be the same. The flatter you hang it the tighter the ridgeline will be. So it's not the distance between the trees but how "flat" you try to hang.

One guy I camp with just can't seem to grasp this. He pulls his HH banjo string tight and hangs and the max length he can all the time. The guy weighs probably 240 so I'm just waiting for something to let go. I've tried to show him that he can easily hang higher on the trees and go closer together with no problem but he just doesn't get it. I think lots of folks have that idea left over from the old backyard spreader bar hammock days.

[DemostiX]

The structural ridgeline (SRL) lets your hammock angle be independent of the distance between the trees (provided distance>length of hammock.)

Think of a continuous rope going from tree to tree. Now, think of attaching your hammock ends to the rope with really secure short prusiks. (Conceptually, that rope going from tree to tree could be beam and the attachment of your hammock to hooks attached to the beam at different distances.)

The length of line between the prusiks becomes the structural ridgeline.

Lets say you had, before climbing in to your hammock, cranked hard on the rope between the trees, so it is taut. There is still some weight you can put in the hammock, when you climb in, that will completely relax the portion of rope between the prusiks. Pretending that there is no stretch in the hammock, the angle of the hang between prusik and bottom of the hammock will not change, no matter the weight you add, but the degree to which you offset tension in the continuous line and the balance of forces in that line will change. So, the tightness you are worried about is nothing to worry about, so long as you have not over-loaded the line.

When Warbonnetguy (elsewhere) advises on tightness of his included SRL, he is assumes the ropes from hammock to tree are themselves at about a 30 degree angle, which he advises, so the tension in the supplied SRL is a function of the difference in the angles of ropes and hammock. Where there is just a slight difference, the SRL will be easily flexed. That SRL is serving almost entirely as guidance to flop in the hammock and negligibly as a load-bearing member of the suspension.

Another HF member has usefully pointed out that longer whoopies can indeed be very valuable: They can overcome the height-of-strap-on-tree limitation. You just need strong enough whoopies (or ropes) and a true and strong enough SRL.

It seems there's not been an engineer or rigger or rescue tech visit here (in a while) to illustrate some of the basic calculations of vectors. Or even better, to present a spreadsheet -- or these days, a phone app -- with the inputs and outputs. The vector physics is basic, but complicated by stretch in the materials that alters the lengths of the hammock and lines, which alters the angles.

[MAD777]

The flatter you set up the suspension, the more the force will increase on your "non-structural" ridgeline. Obviously, it is becoming a "structural" ridgeline, at least until it fails.

So, you simply need to select your ridgeline material to match the way you hang.

Many people are fine with 1.75mm Zing-it, but if you're pushing the limit, there are options - 2.2mm Zing-it, Dynaglide, or even Amsteel.

[fifty2eighty]

Thanks for the replies. I am going to head to the park today to do some tests and the information provided here is certainly going to help.

I am going set up the ridgeline at the 30° angle length (83%) and feel the tension. If it's tight I'll adjust it to try the "turn between thumb and forefinger 'S'" and see how that affects the angle of the hang.

I'll keep in mind the height I have the straps on the tree and the overall angle from tree to hammock, but this helps ease my mind a little bit about the tension. The first time I hung and heard the "twang" my immediate thought was "uh-oh, is this thing going to break and slap me?"

I have zing-it coming this week but for the time being I want to stick with the amsteel just as a precaution.

I am still a newbie when it comes to hammocks so having this type of feedback really helps!

Thanks again!

Dave

[DGHPTS]

Hey All,
I'm a newbie and have been reading this forum for a couple of weeks now.
I've always camped on the ground before and since I'm getting older I still want to camp but want to be more comfortable, hence moving to a hammock.
I purchased a SBP hammock, a bunch of Amsteel blue 1/8th inch line, and a set of straps used for tying down quadrunners that are rated at 800lbs (in small print 1600lbs breaking strength).
After reading the forum, I changed the suspension to 6 foot whoopies, and the straps. I figure I'll wrap the trees twice and use a marlin spike knot with two strap thicknesses (the straps don't have loops so the loose ends will just be doubled) to connect the whoopies.
I read more (thanks Grizz) about structural ridge lines and made one with a whoopie for adjustment for the SBP using more of the same Amsteel.
Since I haven't hung yet (can't wait), I'm concerned about how the SRL (if you haven't noticed I pick up abbreviations quickly) will affect the side to side pull on whatever I am hanging from.
I'm worried that with the SRL to set the hang, the suspension whoopies will put too much stress on the straps (though doubled they should hold 1600lbs normal load).
I worry because I'm a "chunky" guy (250lbs), and I'm really looking forward to hanging!
Basically, I see a lot of posts saying there shouldn't be an issue, but not having hung yet, and after looking at the charts mentioned elsewhere, I'm afraid I'm going to pull a tree down or snap the straps.
I've looked for pics that have been posted about SRL's but haven't seen any showing anyone "in" the hammock, so I'm wondering if with the SRL, the angle to the tree is 0 degrees which in my case would an "infinite" load on the tress and straps.
Am I over thinking this? I would hate to be the "the one" the rangers talk about destroying the national forest by pulling down trees

[Bubba]

...
I've looked for pics that have been posted about SRL's but haven't seen any showing anyone "in" the hammock, so I'm wondering if with the SRL, the angle to the tree is 0 degrees which in my case would an "infinite" load on the tress and straps.
Am I over thinking this? I would hate to be the "the one" the rangers talk about destroying the national forest by pulling down trees

In this pic of my wife in the hammock, you can see the SRL and the 30 or so degrees of the suspension. I use SRL's as a yard stick most of the time to get my sag. Ordinarily it is taut but not tight. It is only tight if I have two trees that are far apart and I cannot get the attachment points high enough on the trees.

[DemostiX]

The lower the capacity of your ropes and straps, the more you have to worry about. Maybe, those of us who cannot easily attach straps high up the trunks of trees should find here, somewhere, the obvious solution: to use straps and lines that are a little heavier, and a functioning Strutural Ridge Line.

The added weight and cost of more robust suspension parts is small. 100 ft of Amsteel Blue (AB) in the 1/8" / 3mm nominal size has a break strength of 2400lb. 7/64" inch (AB) weighs 3oz less per hundred feet. But you only need 1/3 that for two 7 foot slings.

So the cost in weight is 1oz. By volume (and weight): 2 tablespoons of water.

If you wish to save on air-conditioning costs, buy and install the smallest unit you can find.

[nothermark]

You are over thinking it a bit. The SRL should be under tension and set the lay of the hammock. You can adjust it and see how it works. That makes the major factors in hanging how high you can reach and how far apart the trees are. You will probably go for as high as you can reach just to keep your butt off the ground. ;-)
Your other option with the straps is to tie an overhand loop in each end so you can slip one through the other or both through a climbing grade carabiner along with the sling. Multiple tree wraps are good for the tree and an easy way to use up strap you need for the big one's/long spacing. What you said and what I added all are used by various folks. Mix and match as you work out your method. you may be asurprised how much things change after the first time you get in the hammock. ;-)

[Ramblinrev]

You are over thinking it a bit. The SRL should be under tension and set the lay of the hammock. You can adjust it and see how it works. That makes the major factors in hanging how high you can reach and how far apart the trees are.

When you are adjusting the ridgeline for comfort be aware that 1" makes a huge difference. I used to adjust my indoor sleeper by increments of 1/4" just to make sure I didn't over shoot the mark.

You can always you a branch or trekking poles to push the straps up higher than you can reach. If you use the biner you can shake the strap loose enough to drop down to reachable levels when you take it down.