Crazy idea: inside-out shelter?

As mentioned, I shrank the dimensions (except for length) and made a full-scale mock up to get a feel for the size of the inside-out bug bivy or "bug out bivy" when closed up tight with tarp overhead. First thing I realized is the wasted space below my feet (too long!) Otherwise it felt good… So, shrinking the finished length to 84", I realized I could also substantially shrink the material list to 3 yards Membrane silpoly, 3 yards NS50, 2 yards PU4000 and 11 ft #3 zipper. Here's the hypothetical pattern sheets on how I plan to do this: Projected weight sans stakes and poles (which I seldom carry and use sticks anyway is 12.4 oz. Given this weight and further thinking on a removable tarp idea, I don't think it's necessary to have that feature and I'd rather avoid the fuss in set up so will plan to sew the tarp and noseeum down the entire ridgeline and have zippers on the hypotenuse of front door to zip and roll back tarp from inside to the extent illustrated in my first drawing. Oh yeah, material cost dropped to $56.60 sans shipping in the process too…

Well, that was a little trickier than anticipated, but here it is preseam sealing. Ended up ordering materials from dutchware (was impatient waiting for #3/zipper to come back in stock at ripstopbytheroll). Turned out to be cheaper: $54 with shipping and roll of thread. Weight is 13 oz. On the nose with cord. I know I talk a mean game of not using poles and stakes in favor of sticks, but for convenience of photo opt, a bit of a hypocritical. Last photo shows solution to unexpected problem of pulling tension on tarp edges. If one were willing to pay 3x as much in materials and use lightest materials, such shelter could get below 8 oz. This was a good compromise for a prototype. Not sure how happy I am with it, but definitely more hospitable than a bivy…

Matt, did you use .50 or .67 noseeum? Appears to be a good job from what I can see. The bivy looks a tad small, but at least it should keep you dry and bug free. Maybe you could make another one with some of the new 7d .68 oz /sq yd material from Rockywoods. It would be nice to see a pic with you laying down inside to get a better perspective on size.

How do you keep rain from running down the fly and right into the floor? -Tim

I was going to suggest that a hose test in the backyard could be a good idea before testing it out under rain on the trail.

I'm using the .67. AFAIK, ripstopbytheroll is the only source of NS50…? Good suggestion for pic for scale. Will have to get more pics another day. Base of door is 36" height is 36", tapering to half that at foot. Length is 84" and here is a pic of half zipped open close with neoair if that helps You're right that it's small! A small footprint can be nice though. I'll have to see how functional this thing will be for fast and light trips…

So yeah, the biggest design flaw is the bathtub floor. The idea is to have the tarp roll down into a trench created by bathtub wall and overlapping noseeum… If that makes sense. I fear the trench I'm this design is not deep enough. This was compounded by the slack in the edge of the tarp. That problem seems to be remedied by the tensioner buckle/lineloc pictured above. Still, the tub walls will need to be reinforced. Other than sewing an additional couple inches, any suggestions? I was thinking a shock cord to pull the middle of wall up to ridgeline midway down. Don't want to over engineer the solution either…

Bathtub w/ netting trough is the way to go, a la Z-Packs tents. I'd continue to follow the Z-Packs example – tension the bathtub at the corners to keep the whole thing taut. If you have some solid fabric coming back from the head wall on either side, your solid side walls don't have to go so far down in to the corners and they'll be easier to attach and tension. Does the front vertical edge of the side flap zip to the head wall? If you do the above and give them some overlap, you can lose the zipper in favor of velcro. Not a huge win, but it'll seal itself once the side flaps are attached in the corners, and you avoid zipper snag/wear issues (put the hook side velcro on the side flaps).

Thanks for input, Rene. Thought i'd share the solution i came to. I had enough floor material left over to raise the tub walls by 2", tried to add tension as you suggested, but not pleased, so added shock cord on either side midway down to pluck the walls up, like this: Now I'm pretty happy with this, it brought the weight up to 13.7 oz. sans stakes. With 6 easton stakes (repurposed from TT contrail), weight is 15.5 oz. Good entry level weight for <$60, although that could be halved if one were willing to spend $15-20/oz. to do so… Still need to seam seal, will do that soon. Then a proper hose test, then onto the trail.