I'm making a bug bivy for use under some pretty minimal tarps and am thinking it might be nice to add a little waterproofing in the foot area.

Bottom will be silnylon, top nanoseeum. What I'm tentatively planning to try is to add a flap with about a 16" of Propore (from a Driducks tarp, ~ .8 oz) that I can pull over the foot area when it's raining or when my tarp setup makes wetting of my bag from condensation at the foot of the tarp a potential problem.

This will cost only ~ .2 oz over adding a straight-up Propore footbox (weight savings from less nanoseeum) and will mean that I can maintain full breathability of mesh when I don't need the Propore.

To hold the flap in place when needed, I would either leave a little extra on the sides to tuck under, or would attach a snap on each side.

Advice/thoughts?

Thanks much!

Best,

Bill

Do you use a packliner? Using your packliner of adequate girth & height adds nothing to the weight of your net bivy, can be pulled up as much or little as needed for blowing rain, is completely waterproof, does not need to be breathable because you do not breath into it, drys quickly when shook out, is cheap & easily replaced, & when you do not need it to deter blowing rain under a tarp it is a packliner!

I hadn't thought about this. Certainly it'd be better than nothing in a pinch, but I would have thought that it'd promote accumulation of moisture from perspiration. Gives me something else to test, but I'd be interested in other people's experience.

If it's generally OK to have something non-breathable at the foot of a bivy, how far up can you come before it starts to be a problem?

Best,

Bill

I've used my pack liner over the foot end of my sleeping bag on occasion, and usually end up with a damp footbox in the morning. A little strip of propore with a mittenhook to clip it up over the feet sounds like a way better idea.