the structural ridge line will maintain the angle you chose through it (so the hammock will always be at that angle), that is its primary purpose. it only affects the hammock though.
this means a few things
- you can pull the suspension at any angle shallower than 30 degrees, and the hammock will still work great (so as tight as you want, to use your term). your suspension will be over stressed though, so will the trees or whatever you are hanging from (do not underestimate this: i pulled a brick out of a wall while making sure a whoopie sling i made works acceptably, i just loaded it with my hand, not even my full weight, but it was somewhere under 10degrees, maybe under 5, and dyneema doesn't stretch to increase the angle, so it didn't take much)
- the above means that, when the trees are too far apart, you can still get a confortable usable hang, without reaching beyond your height up on the tree. this also means the further the trees are, the worse the overload will be, so better to set a limit for yourself, at which you know you either _will_ climb the tree, or find different trees.
- you cannot overload the hammock if the ridgeline is attached properly, you should only be able to overload the suspension. this means the hammock will feel fine all the time (even when the tree is about to topple over you, as somebody mentioned), so beware when using a structural ridge line, you need to think, you can't just go by feel.
- as mentioned, dyneema will be very unforgiving with this. it is wise to insert some nylon in your suspension; although the stretch is annoying when you use only nylon, a short component which is stretchy will help you avoid some dangers: when not overloaded, a sturdy nylon tree strap, for instance, will hardly sit back when you sit in the hammock, if everything else is dyneema. as the angle gets shallow, and overload happens, it will stretch proportionally to the load, which will do two things: it will warn you you're pushing it, as you'll feel the flex as you sit in (which, at normal angles and loads, is almost imperceptible to you), and it will slightly adjust the angle as you load it, to mitigate some of the overload. i know dyneema is all the rage etc, but i think we tend to forget how useful a bit of elasticity can be, in suitable quantities.
- the angle of 30 as measured from the horizontal is a rule of thumb (and also happens to be the magic angle at which the load on each anchor point is exactly equal to the weight of the system), anything less will increase the load (so 15deg will take it near to double the weight of the system, while 45 will take down to under 3/4, to give you an idea), in other words your mentioned 35 would be a bit more sag than usual, and less load, it's well within the range, you might like it and there's nothing wrong with it for sure.
As a slackliner, I'm used to cranking some webbing horizontal between a couple of trees, and then jumping up and down on it. I've never damaged a tree (as far as I know), but I choose healthy-looking trees with thick trunks for this. I destroyed a few fences and posts with my slackline before realising the power of the force it exerts.
Translating that to hammocks - if your trees are healthy and solid, I can't see how a tighter-than normal hang will do damage to the trees. But you might want to have stronger-than-normal suspension and a stronger-than-normal structural ridgeline, as they'll be taking the strain. The hammock itself won't be taking any extra strain.
The main use I can see for a tighter-than-30-deg-hang is when you have trees that are very far apart, which make getting the straps high enough impossible. If your webbing, suspension, and ridgeline are strong enough, go for it.
As Nanok stated, the ridgeline will guarantee the "sag" in the hammock, but the angle of the suspension will drastically change both the tension carried by the straps as well as the lateral load placed on the tree. I got curious about the relationship, so I plotted the Force Ratio for tension force and lateral force vs. the hang angle. Just multiply your weight times the force ratios for your given hang angle, and you can determine the tension and lateral forces.
ForceRatiovsHangAngle.png
slackliners don't use dyneema "suspension" (the slack line is the suspension here), it is typically quite long compared to the hammock suspension, and will stretch considerably as it's usually nylon or polyester webbing woven to not be static. you will also tend to crank it down quite a bit before you get on it, so you will know the trees can't take it before you get on it (as the load you add by getting on it is in fact not that much comparatively). and lastly, the protection you slackliners tend to use on the tree to distribute the load is a little bit different. i'd be careful how far i extrapolate from one to the other, if using dyneema (like whoopie slings etc), i would advice to not extrapolate at all
Here you go...I also attached the Excel file in case anyone wants to play around with it.
ForceRatiovsHangAngle2.png
I wouldn’t call 30 degrees a “goal”. For me, it is more a starting point to finding comfort - which is my goal. Other numbers are offered - like the distance the ends should be apart is somewhere between 83% and 86% of the hammock length. You find that most verbal (text) descriptions say 83% while hammock calculators use 86%.
That’s not to say that in pursuit of comfort you should hang with a 15 degree angle suspension. If you cannot find a sweetspot around the 83% to 86% range, there might be something else that needs considering.
The ridge line give you a constant sag if you need to hang tighter than normal - but the increased stress is still there. If possible, it’s better to use the ridge line as sort of a measuring tape. As you set your suspension, it indicates how far apart the hammock ends should be. You can adjust the height on the tree and length of your suspension to meet the goal of that ridgeline being just bendable but not guitar string tight.
There are other discussions about if that tightness should be measured while you are in the hammock or out of it. Because I am out of the hammock when I set it up. I use the “out of the hammock” tension as my “goodness” indicator.
In order to see what few have seen, you must go where few have gone. And DO what few have done.
Good sense from recent posters - except that considering suspension angles lower than 15 degrees is irrelevant. Pull your suspension with structural ridgeline as tight as you possibly can, and it will sag to about 15 degrees when you get in your hammock. The effort needed to pull it tight goes up exponentially, too. What that means is that if you are forced to use trees very far apart, you may increase the load on your main suspension line to twice your weight, but probably not more than that. At 15 degrees, the load on your hammock (set at 30 degrees by the ridge line) remains roughly equal to your body weight, and the load on the ridge line is in the same ballpark (not doubled). Don't be overconfident, though. The ability of any given tree to withstand horizontal forces changes with wind speed, soil saturation, tree health, and cosmic whim as it pertains to your personal karma. As to the strength of the various components of your hammock suspension, the laws of physics are fairly consistent.
Last edited by WV; 08-04-2020 at 13:18.
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