Thanks to ACL reconstruction, I spent this last week doing something I never have time to do - making gear. Here are two of the results:
The first bivy I made is one with the dark bottom. Well, technically the first one I made was a full-size paper mock-up and this only after countless scale mock-ups. The problem was I wanted to do a 3D shaped hood out of one piece of fabric and getting a design like this is quite complicated. If you look closely you'll see a short, vertical seam running from the apex of the mesh to the top of the hood (where your forehead might be) - the two "arms" of fabric that come together here are designed to create the conical, 3D shape and thus added room to the hood. The end results were worth the countless iterations of tweaked prototypes as the hood really fits well and creates a roomy, but not boxy shape for your head. In fact, the mosquito netting doesn't really even rest on your face at all, but there is a tie-out at the apex of the mesh (or base of the hood really) to use if necessary. Another requirement for me - and the primary reason I didn't buy an MLD or Katabatic bivy - was to have a long, two-way, hip-to-hip zipper. I find that when there aren't bugs or blowing sand, I like to keep my bivy unzipped at least at my chest and sometimes further down so that my upper body and head are free. The zipper achieves this, as well as making sleeping pad, sleeping bag, and body insertion very easy. I was willing to pay a little weight penalty for this key comfort feature. The zippers are #3 YKK with two, double-sided sliders with spectra pull tabs. Another design feature is the bathtub/standard combination floor. This first bivy has a bathtub floor at the head, but a round "sleeping bag foot box." This creates a really nice, nearly seamless space at the head. There's no real reason for the footbox except aesthetics - for some reason I liked the round profile. In terms of dimensions, the bivy has a 54" circumference at the foot and 76" at the shoulder (or just below the shoulder as I find right around the chest to be most critical for comfort). The usable length is 80". I find these dimensions to be roomy but not baggy for myself (5' 10", 155 lbs), a standard 72" x 20" x 2" (think Neo Air) pad, and a 3-season down bag. There is room to sleep in any position (I usually sleep on my side or belly) and while on my side I can draw my knees to my chest without too much of a problem. Other features include four tie-outs (one at each corner), an Ultrasil stuff sack, and a 3/32" shock cord with mitten hook for suspending the mesh. Most of the seams are French seams with the exception of the mesh panel and zippers. Contrasting bar tacks reinforce zippers and the mesh panel tie-out. The bottom and foot panel are made of charcoal grey Ultrasil, and the top is made of black Momentum 90. Weight: 6.9 oz. This bivy was commissioned by a friend but I'm taking offers if you want it ;))
The second bivy is my baby. This is the one with the Cuben (white) bottom. Learning from the first one, I decided to tighten up the dimensions from the shoulder to the foot by 2" (thus a 52" and 74" foot and shoulder circumference, respectively). This is still roomy and comfortable, but a little bit more athletic of a fit. It would feel just as room as the first bivy with a thinner pad or bag. All other dimensions are the same. One other difference is the footbox - this time I incorporated a true bathtub floor design at the foot, but extended the panel upwards to provide waterproof coverage right up to where it meets the top panel. An advantage of this design is that the entire bivy has just two pieces (top and bottom), not including the mesh panel. This required some complicated cutting and sewing, but in the end is worth it. It is just as aesthetically pleasing and while I have no complaints about bivy #1's design, future bivies will use this new footbox design. The white, bonded Cuben stuff sack in the picture fits the bivy (but is currently filled with my tarp) and is about the size of a 16 oz bottle. The bottom of this bivy is CT2K.08 (0.75 oz) Cuben and the top is Momentum 90. Weight: 5.0 oz.
Both bivies are pictured with standard 2" pads and 3 season bags inside, as well as full-size pillows in the head area to fill it out and show the 3D shape of the hood. Not sure if these photos will work but here goes...