Thread: Origins of 83.333% [5/6?] guide

1. I am myself a terrible estimator of the angle by sight. Yes, unless people set ridgelines many are hanging with more sag than they think.

If sleeping through the night is an objective, then one approach to success is sleeping in the same bed, which is to say with the same setup / sag, whatever it is.

Another is Shug's: Hike hard, be very physically tired and quite tolerant of any set up, falling asleep and sleeping soundly.

2. Originally Posted by DemostiX
I am myself a terrible estimator of the angle by sight...
All joking aside, the thumb and finger method I posted a photo of gets the angle very close to 30*.

3. And taking you seriously:
• The eye is pretty good at detecting a 90 degree angle.
• Let's trust that and use a ruler or tape measure instead of a protractor, which few of us have around and can read to 1 degree.

• Get your thumb and forfinger into a 90 degree angle.
• Measure the distance between tip of thumb and tip of forfinger.
• Take a provisional measure of horizontal distance through the forefinger, say, to the middle of the base of the thumb.
• Go to google search or any calculator and put in the ratio of forefinger length to the 'thru-the-air hypotenuse of the triangle. Example 5.25 /6.
• For each .01 difference from .866 you are 1 degree off of 30 degrees sighting a line between tip of thumb and tip of forfinger.

Works for me, thanks. I naturally sight this way a little flat, the ratio being about 0.88. But, I can adjust.

4. I think I am going to scribe a 30 degree angle on my stuff sack.

5. Angles may be hard to judge, but for 30 degrees, the length of the suspension from tree to hammock is twice the distance measured on the tree from the suspension point down to the height of the hammock ridge line (height where the suspension attaches to the hammock).

If you run a spare piece of cord along the suspension, then fold it in half and check the height of the attachment point, it is easy to judge if you are very far off from 30 degrees. It also helps me estimate the adjustment necessary, either in suspension length or height of attachment.

6. I would suggest that the answer is more empirical than mathematical. rule 1- hammock needs some sag to give a comfortable lie. rule 2 (probably came along later than 1) a hang angle of 30 deg is desirable as then the strain on each suspension cord will equal the body weight of the user, and probably not damage the tree if using straps (rather than ropes) . A typical hammock then (Hennessy) was 10' or 120" long. A fixed ridgeline was needed to hold up the bug net. How long? Well.if it is 100" (5/6) then with you lying in the hammock the angle of the chord will be about thirty degrees, and it will be in slight tension (you can reach up and twist it between finger and thumb). If more than30 deg, then the ridge line flops and the bugnet is in your face. If less than 30 deg then the ridgeline twangs like a banjo, and you know you will likely damage the trees, and break in the middle of the night dropping the bug net onto your face,. So the 100" ridgeline acts as an indicator of a low stress comfortable lie. 5/6 is 83.3 %. . As many say here, a useful rule of thumb, and a starting point for developing personal preference. Like all rules of thumb, they tend to be empirical.

7. Perhaps Dutch can chime in since his ridgelines are also sold at 83%.

If you scroll to the bottom:
http://www.dutchwaregear.com/11-ft.-...mmocks-en.html

8. Originally Posted by krugd
I think that's probably it. Someone dialed in their own hammock and then started passing around the number. Though 83% sounds a bit too exact for anything empirical.
Uneducated question: Is Fibonacci at work in here somewhere? After all, the Golden Section is found at work in nature and we're hanging in nature.
Also, Does the length of rope/strap from the tree to the ends of the ridge line have any bearing in this ratio?

9. Is it possible that the 83.3% guideline represents the sweet spot that gives the widest 'flat' area at the center of a symmetric, gathered-end hammock, balanced against lateral force on the hang points? This would be the saddle point of a function described as z = f(lay width, force). Both lay width and force would ultimately be dependent on hang angle. I've access to mathematica, but not the time to relearn. I do, however, have the time to drop in, post a question, then speed away. *smoke bomb*

10. On a slightly more esoteric note: 83 = HC = Happy Camper, Hammock Camper, Hard Core

I hope I added some clarity there

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