I’ve been tossing around this hammock shelter AKA “air bivy” idea for some time. The ultimate goal: something lighter, faster, more compact and versatile than a summer ground system. Ideal total weight would thus be around 8 oz., a seemingly impossible target. But if material costs were no object, a minimalist design could certainly crack half a pound.
With no major fastpacking adventure on the horizon (save for maybe a pedestrian Hurracan), I’m not all that inclined to dump three figures into a prototype. For now, I’ll stick with the $5/yard materials, which still yield some promise. Taking the less-expensive route, I’ve whittled it down to 11.5 oz. The evolution of this design is worthy of a few quick paragraphs.
My first DIY hammock idea for BMT 2009 was a flop. Even with the insulation built in, I was too cold on test hangs and took to the ground. It didn’t help that I’d never really gotten used to sleeping in a hammock. Fast forward to my AT 2013 hike: I longed to get my bony body off the ground in rocky VA. Shortly after finishing, I got back to brainstorming.
For the next iteration, I used a $5/yard WPB shell material available from milesgear. But its bulk and weight (2.3 osy) soon got me looking into non-breathable alternatives after a test on the CFAR. I also decided that a longitudinal zipper was worth its weight versus a fussy drawcord entry/exit. All along, I kept the black 1.2 osy polyD hammock body.
Air Bivy V3
The skunkworks continue with iteration #3 of the air bivy: An 11.5 oz. poncho/shelter with full rain/bug protection and a one-minute setup time. Inspiration came to me one night in Virginia during my southbound sub 60 AT hike. I was having difficulty finding a decent spot to camp. I longed to hang between two of the countless trees on the trail. After my hike, I began researching hammocks with the goal of finding a summer shelter/sleep system that was lighter, faster and more versatile than what I carried in 2013. More info available at http://sub60.wikispaces.com/Lab
Posted by Matt Kirk on Tuesday, September 1, 2015
By repurposing a homemade cuben poncho/tarp, some scrap zipper and netting, I was able to shave 2.5 oz. off the next prototype (above). But some things still needed fixing. Though less than ideal for an entry/exit in the rain, eliminating drawcord ends on this prototype proved to be a mistake as they allow the hammock to be used separate of the bivy.
So here we arrive at the latest version. Although curious to try 1.0 or 0.9 osy hammock fabrics, I’ve stuck with the polyD (mainly because I’m stingy). The latest bivy/sock is constructed from membrane sil poly (acquired on sale for ~$5/yard), leftover 0.5 osy nanoseeum and a #3 zipper. Suspension: amsteel with tubular grosgrain sheaths for the trees.
I’ve yet to decide if I want to add the extra weight of a poncho hood to this prototype. At 6’2, I’m probably too tall of a guy to be playing around with a 9’ rig. Still, I think it’s safe to say that the concept is getting somewhere. As much as I enjoyed the recent “sub-$60 inside-out” tent project for my panhandle adventure, I’m now more tempted to take to the air...