Apparently, signature that I used from 2006 no longer tolerated so now deleted.
Watertones, I think BlueSkies just about sums it up, play with your hang until you reach that point where you're comfortable. All the numbers are good for starting points but there are too many variables and the only thing that matters is a good comfortable nights sleep. It took me a while to get to the point that I was satisified then I made a new DIY and changed suspensions which changed everything. Then I hung the new hammock on my indoor stand and had to readjust for the shorter length of the attachment points. Even now I can't stop tweeking the hang looking for 'better', may have something to do with being retired.
Most of us end up poorer here but richer for being here. Olddog, Fulltime hammocker, 365 nights a year.
If we take a simplistic view of the hammock, your weight is distributed through the structure into three tensions (or equal and opposite sets of forces) as shown below.
The table below (if my math is correct) shows the multiplication factors of your weight on each of the tensions for different tensions.
So at the popular 83% ridgeline length and 30degree hang angle the ridgeline is tensioned at the equivalent of 24% of your weight. Just 2% shorter and 2degrees less doubles this and the same in the other direction elimates the requirment for the ridgeline totally.
According to the "Hammock Hang Calculator", with a tree distance of 15 feet and a ridgeline length of 108 inches, you should only need to attach your tree straps at a height of around 6 feet. However, these calculations are just an indication. The ridgeline really is the best tool for getting a consistently good hang.
You say that you are using an ENO hammock - as far as I know, they don't come with a ridgeline. I guess you added that yourself, correct? So maybe it's not the hang angle or the height of the tree huggers, but your ridgeline is very short?
I mostly use a WBBB, and I'm happy with the pre-installed ridgeline length. I didn't find it difficult to get a good angle / good ridgeline tightness, although there definitely is a learning curve. If you need a lot of sag = a short ridgeline, that's fine, but in this case the 30° angle rule doesn't apply anymore. The more sag you want, the steeper the hang angle.
Provided that your ridgeline has the right length, hang your hammock at roughly 30°. Get in the hammock and check if the ridgeline is tight or loose. Also check how far off you're from the ground. If the ridgeline is too tight, let out the suspension. If this means you are getting too close to the ground, you'll need to get the tree huggers up higher. Check again. If it's still to tight, let out the suspension more (and probably put up the huggers up higher). This method has never failed me outdoors.
I'm happy to bookmark this post with that first impression. I want to come back to this later after thinking about dynamic vs static analysis. I wish I had seen this earlier.
Last edited by DemostiX; 02-28-2012 at 14:27.
gd___, sorry but I think there's an error in your spreadsheet.
You show the sling tension (hammock suspension tension) as having a multiplier of 2.0 at 30º hang angle. It should be a multiplier of 1.0 at that angle because the weight of the person is distributed to both ends of the hammock/suspension.
Does correcting that change anything else?
OK: Here's the problem with dynamic vs static analysis, which unfortunately arises in your example: The table can only be read by varying rows, with the column fixed. That means you go to the field with a specific ridge-line % which fixes the sag angle. You can then vary the sling angle, which changes the row and read out the change in ridge-line tension and as has been most often shown before, the sling tension.
What you can not readily do is change the ridge-line length and sag angle, and read out the tension as you have done, because shortening the ridge-line reduces the sag angle at the same time, putting the hammock on an earlier row row.
What the chart does show, and beautifully, is that questions about "appropriate" ridge-line tension depend so much on the sling angle. If that angle differs by just 2 degrees, the ridg-eline tension is much different. (It would help if the diagonal of zeros were include.)
Again, unless one is certain that you have hung the hammock EXACTLY with the same sling angle as the maker assumes when he made recommendation about ridge-line tension, matching ridge-line tensions is meaningless.)
I'll check the spreadsheet tomorrow to make sure but I think it will halve all the factors (or the factors should apply to half your weight) so the ratios should be the same.
@DemostiX - if we assume zero stretch (which should be true for the suspension, maybe not the hammock) the angles would remain the same for dynamic load but would be applied to a greater affective weight.