Nice thread. Good charts about the tension of the suspension ropes.
I have a doubt tough. What would be the tension in the structural ridgeline in a hammock with an angle of 30° and a person of lets say 200 lb in it? I have thought about adding a ridgeline to my hammock but don´t know how much weight should it support.
I have posted diagrams and spreadsheets in various places on that over the years for a simplified analysis of that. Even that simplified analysis is more complicated than most folks are interested in. The force on the ridgeline varies as a function not only of the weight of the occupant, but basically how much it is raising the hammock as it 'limits' the sag of the hammock itself in that simplified analysis. When it is 'raising' the hammock very little, it is doing very little work and has very little force. When it is 'raising' the hammock a good bit, it is doing more work and can have lot more force on it.Originally Posted by nailer
In my opinion, what it all boils do to is that for our purposes using a ridgeline that is at least half as strong as the main suspension line is a good rule of thumb. It is also very desirable to use a low stretch material for the ridgeline. Even the initial stretch of the low stretch braided ropes we often use can be like a fly in the ointment for ridgeline use. I think you almost want to pre-stretch the ridgeline rope before you measure, cut, and install it or anticipate how much a new, unstressed rope will stretch under its initial load and take that into account.
Youngblood AT2000
Here's another Q:
Hanging the hammock, the general advice I've seen is to have the hammock at about "chair height" - I'm guessing that would be right about knee level, like an easy chair, correct?
Is that measurement done at the belly of the hammock as it hangs, or the sides at their lowest point? Loaded or unloaded?
Mike
That is complete and total personal preference IMO. Some folks who camp with dogs like to hang lower to the ground so they can skitch the pooch.When I hang my HH I like to end up at least chair height at the sitting part of the slit because it is easier for me to get out. A little higher is even nicer. As long as the hammock doesn't scrape on the ground or rocks underneath and abrade the fabric I am not aware of any performance issue that changes one bit.
I may be slow... But I sure am gimpy.
"Bless you child, when you set out to thread a needle don't hold the thread still and fetch the needle up to it; hold the needle still and poke the thread at it; that's the way a woman most always does, but a man always does t'other way."
Mrs. Loftus to Huck Finn
We Don't Sew... We Make Gear! video series
Important thread injector guidelines especially for Newbies
Bobbin Tension - A Personal Viewpoint
Right - just wanted to know what the 'chair height' reference was - easy chair or bar stool, and empty or loaded?
On other matters...how the HECK do y'all get tautline hitches snug enough to NOT slip???? I've been trying to see how comfy (or not) a knee-height "belly" was for sitting in (partial weight, have it strung up between a couple equipment bays at work that can't take full weight), and the knots keep slipping up the line!!
And yes, I'm tying them correctly and they're snug.
Last edited by MikeN; 07-09-2010 at 16:13.
Mike
Mike, I don't think that anyone uses taut line hitches sucessfully for the hammock suspension line.
Youngblood AT2000
I agree!!!After trying several different knots (thread in suspension forum) Grizz advised that I jam a buntline hitch - that worked.
Back to the chart... a bit of playing in excel gave me some numbers based on the following - I'd appreciate a double-check on my calcs:
A 30 degree angle is a 1:2 rise - 1 unit of rise for 2 units of length.
The hammock stand that TrailH4X designed has a span of 12 feet 4 inches, and the height of the attachment arms are a bit over 5 feet (62" based on 6 foot hypotenuse and 60 degree complementary angle).
*IF* your hammock is centered between your attachments, the difference between the total span length and the ridgeline length, divided by four, tells you how high above the ridgeline your attachment should be for a 30 degree angle.
So, a 148 inch span minus a 100 inch ridgeline (my Traveler hammock) makes a height-over-ridgeline of 12 inches. (148-100=48, divided by 4 is 12").
For the 'belly' of the unloaded hammock to hang at knee height, I need the ridgeline to be at a height of 48 inches. With a 12 inch rise to attachment, I can set the attachment height at 60 inches and still have a bit of leeway to play with, without having to change the angle of the attachment arms or have the hang angle too flat.
Mike
Youngblood, thanks a lot for your answer, that really helped a lot.
I think I will look for some nylon braided cord or an accesories climbing rope when going to the city for the ridgeline. Has not seen anything like Amsteel here yet.
Sorry to disagree, but I just was this week experimenting with knots on my Royal Navy hammock suspension line, 11mm yellow twisted polypropilene rope, and it worked just fine. Well, most of the time
I was looking for a knot that didn´t get too thight after use.
Right now it is setup the traditional way, with a simple sheet bend over the nettles, like in the image below. Sometimes this knot slips when the hammock is tauter, but if I make it a double sheet bend it works perfect all the time. Anyway, if the knot didn´t slip when I tried to get in the hammock, never sliped later, so far.
I was just about to buy one more hammock like the mentioned above, and suddenly they were no more in stock.
Maybe I made too much publicity of them.
Should have known better, for $15 + $6 s&h it was quite a deal, and I waited too much to make my mind.
Wonder if somebody here get hold of one.
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