Bivy moisture dam

[R]

Interesting!

I opted for a center vent.  Lighter, simpler, proven.

92″ x 24″/38″/34″, 5.5oz, Membrane10, Membrane Silpoly PU4000, NS50, French seams throughout, flat pattern (no box corners).  I’m 6’2″.  That’s a 72″ Neoair Xlite.

So far I’ve only used it once, in high winds that saw me back in a tent around 2am, so no sense of how it handles moisture or condensation.  That NS50 isn’t the most breathable stuff – next time I’ll use something else over the face but I think it’s fine for the center vent.  I’m probably going to narrow the foot, which may take another half ounce off.  Length is good, plenty of room in the shoulders.  Zipper is a bit longer than necessary.

One innovation (not shown) that I consider a hands down win is a putting a thin carbon rod across the face, so the lifter doesn’t just pull up just one point (which left mesh drooping in from the sides), but lifts the whole face panel.  I got a 4′ segment of the thinnest stuff available at Tapp Plastics: $5, .07″ pultruded solid rod.  I cut an 18″ piece that weighs something less than .1oz (don’t have the weight handy at the moment) and disappears in the frame sleeve of my pack. At the moment I just have a small grosgrain loop on the inside of the bivy, at the edge of the zipper that I slide the rod through, but it slides around a bit.  So that needs some iteration, but I’m definitely keeping it.  I had some concerns the rod might be too brittle, but it’s got enough flex to it that I’m not worried about it (usual ultralight/fragile caveat still applies).

 

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