To the above I neglected to see that placing the ridgeline this way induces its own compression force on the spreader bar. I've been scribbling around with the formula to determine conditions under which the total compression can be less using long suspension lines and a lowered centered ridgeline, but it is more technical than interesting.
Using a back of the envelope estimate, if the triangle formed on the interior with the centered ridgeline is identical to the triangle formed by the spreader and suspension lines, then we've added a compression force equal to that induced by the triangle formed by spreader and suspension lines.
If the interior ridge line was just two triangles whose apex's meet in the middle, then the added compression is (assuming 36" spreader and 80" hammock length) is about 0.2*W for an occupant lying down, twice that for someone sitting on the end.
You can still reduce the compression due to the suspension lines and rings by lengthening that edge. And you can get overall less compression if you are able to extend those lines a long ways, but that has its own problems.
I should have coffee before trying to do analysis in the morning.
Last edited by GrizzlyAdams; 07-05-2007 at 09:22.
Even skipping every 3rd or so word, reading Griz makes my head hurt.
Purdue AS/EET But it's been awhile. Engineers design on paper, us techs put it together and make it work. Now I remember why I'm a tech...
Bad spellers of the world Untie!
But, I'll have you know I'm joining the tech union. I'm just back from Wally World where I scored 10 yards of ripstop nylon out of the $1 bin. Soon I'll be poking holes in my fingers with needles along with the rest of you.
joining the proletariat,
poncho's are sil. the outermost layer should protect from wind as well as windblown rain especially if there is down or synthetic under the hammock. it seems that loose sil under the hammock might not have the condensation problems you are affraid of. consider a sil shell that hangs so that there is a couple of inches of air gap between it and the bottom of the hammock. this provides more insul. like jeff said, but also gives room for body vapor to evaporate into, and assuming the thing is not sealed around the edges, that vapor wouldn't necesssairly be trapped. in fact when wind blows, it would even act as a bellows and force said air out of the system, but would still protect from direct wind gusts and windblown rain. just something to consider. also, for that matter, since it is open on top unlike the garlington insulator full hammock sac thing, any body vapor inside the loose sil undercover could just come back through the breathable hammock body anywhere there is not a bodypart laying there to stop it, and could escape through the breathable hammock fabric also, this is how heat escapes when there are large air pockets in an underquit, the air pockets don't have to go all the way to the side of the quilt, they just have to be large enough to lead out from under the edge of your body/sleeping bag and will then release air through the hammock itself and into the sleeping area where its gone forever. if the sil shell hangs loose what would keep body vapor from evaporating back through the breathable hammock?
"Man is a stream whose source is hidden." RWE
So handling "controls" on the ridge line is really no problem.
This is brilliant idea.
I can already see where I could take some 1.1 oz DWR ripstop, shape it for an undercover in this manner, sew my GG thin light pads to the ripstop exactly where I want them. The pads can then be lowered or raised into position and they stay exactly where needed. Better than the Speer SPE.
The same with under quilts.
That is also one of the things I really love about the Bridge Hammock - you can adjust the height of the ridge line.
If you tie the ridge line to the spreader bars in any manner, then the ridge line is lowered to a position that you are going to be: (pick one or all) 1. slicing off an ear, 2. hanging yourself, 3. decapitating yourself, 4. always annoyed with the irritating string that always in your way.
Ideally you want that ridge line fairly high and out of the way, but reachable. I've got that with my suspension line lengths.
Last edited by TeeDee; 07-05-2007 at 20:50.