Top fabric choice for bivy

I haven't used nobul2 but I have used nobul1. The website says they are similar. I definitely would consider something different. Nobul1 is whisper thin and has very little water repellency. M90 would be a great bet and I would think the pertex from zpacks would be good too.

I think Nobull2 would have the best breathability out of those three, and since under a large tarp I would err on that side of the equation. Might consider Argon fabric as well.

Ryan

From this thread

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=79752&skip_to_post=681022#681022

It looks like the Nobul variants are more breathable than M90.

I just finished a bivy with a pertex top. It is really nice fabric. It is hard to tell how breathable it is but it seems to be more breathable than the M90.Nobul is very breathable and not very spray resistant. Nobul feels great next to the skin. I used it for the interior of a synthetic quilt and liked it a lot for that use.

I ended up going with Impetus 1.0. Looked like a good balance between the 10D and the 20D, with a decent WPB coating. I'll splash some water on it and see how quickly it wets out. The bivy will have a 6' of zipper, 0.75oz cuben bottom, 0.5oz cuben sides (using 0.5" 9460 tape), and the Impetus 1.0 top. Aiming for a weight of about 4.5oz. Using the LyW8_Bivy plan with some slight modifications to the width of the bug netting and the width of the head end.

Steve