i was debating on doing a structural ridge line for my yukon outfitters hammock as it would make adjusting the tree straps much easier and i wouldnt have to hang the straps so high on further apart trees, but wouldnt this in turn create alot more stress on the trees / straps? i kind of searched around for it but couldnt find any threads on it. is there a calculator for a hammock with a structural ridgeline?
The pressure on the tree straps should only be determined by the angle of the hang and the weight of the load. If you use the ridge line to allow for a smaller angle between you suspension and the horizontal, then yes, it would increase pressure. That being said, any good tree straps should be able to handle any reasonable change in angle. I'll see if I dig up an exact formula for the increase.
"The trees were like lace where the star-beams could chase, each leaf was a jewel agleam.
The soft white hush lapped the Northland and wrapped us round in a crystalline dream."
Robert Service
that's kind of what i was thinking, if i do that i might have to change out my tree straps as im using some cheaper poly straps that are only rated for 600lbs. or i suppose i could just watch the angle of the straps and long as they arent tight as a tightrope and have some angle id probably be fine. reaosn im thinking about doing a ridgeline is becuase its just difficult for me to get my straps high enough without a ladder or something as im only 5'5" and 145lbs lol. nto to mention i have a couple hundred feet of 7/64 amsteel laying around.Originally Posted by Shroud
There shouldn't be that much tension on your ridgeline, just enough to maintain the correct amount of sag.
"Never corner anything meaner than you are...."-Unknown
I found that if I hung from trees more than 20 feet apart I had to pull my suspension line (which included a structural ridge line) as hard as I could to get it more or less to a zero degree angle, and in fact it then might have really been 5°. This is without the hammock attached, that is - almost no weight on the suspension. Then I attached the hammock and got in it, and the suspension lines from the trees sagged to about 15°. (I had someone measure it.) In other words, that's the worst case scenario for tension on the line. Now, at a 30° angle the pull on the lines from the tree is about equal to my body weight, and at 15° it's about twice my body weight. I choose tree straps and suspension lines accordingly. I've used cheap yellow Harbor Freight straps for years, and I've seen no signs of wear on them. I wonder if I'll ever need to use those nifty kevlar straps I got from Dutch. By the way, at that 15° angle from the tree, the tension on my hammock line is 1 x bodyweight (because I set it to always be 30°) and so is the tension on the structural ridgeline. It's just the line to the tree that bears the double load. In theory it could be a lot more, but in practice, you can't do it.
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Last edited by WV; 06-01-2015 at 14:04.
well, im not dead, so theres that. lol i digg it, it was a bit longer than 83% turns out this is only an 8'3" hammock seemed like i needed the extra length on the ridge line so i wasnt hanging off the edge when diagonal. so i guess its not a very wide hammock either lol.
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The tension on each tree strap equals:
Load/(2*sin(Hang Angle))
So with a hang angle of 30°, the tension on each tree strap is Load/(2*sin(30)) = Load/(2*0.5) = Load. With a hang angle of 15°, the tension is 1.93 * Load.
The tension on the structural ridgeline depends on both the hang angle and the hammock sag angle. It equals:
2 * ( (Load/(2*tan(Hang Angle))) - (Load/(2*tan(Sag Angle))) )
So if these angles are the same, there should be zero tension on the structural ridgeline. If the hang angle is 15° and the hammock sag angle is 30°, then the tension on the structural ridgeline is 2 * ( Load * (1/tan(15) - 1/tan(30))) = 2 * Load.
The key point here is that as your hang angle decreases the forces on the structural ridgeline escalate faster than the forces on the tree straps.
this is very interesting, thanks for the info. for some reason it seemed like the tree straps would take the brunt of the weight. but when i tested i had maybe 5 degrees on the ridgeline / tree straps and im guessing about a 35 degree angle on the hammock and i didnt snap the tree straps so i guess im good, lol the tree straps did have alot of bounce but i think thats just polyethylene for ya. ready for my hang next weekendwife and kids and her family will all be sharing a 17x9 coleman 6 person tent with some air mattresses, il be in my hammock snug as a bug in a rug
It has come to my attention that my formula above for ridgeline tension is incorrect. The correct answer is half of what I said it was. So my explanation above should read as follows:
The tension on the structural ridgeline depends on both the hang angle and the hammock sag angle. It equals:
(Load/(2*tan(Hang Angle))) - (Load/(2*tan(Sag Angle)))
So if these angles are the same, there should be zero tension on the structural ridgeline. If the hang angle is 15° and the hammock sag angle is 30°, then the tension on the structural ridgeline is (Load/2) * (1/tan(15) - 1/tan(30)) = Load.
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