ZPacks Frankenstein Groundsheet Panco Bivy

My only question is why buy and sabotage the Poncho which is heavier. Instead you could have just used the straight zPacks cuben groundsheet which is almost 2oz lighter for the same thing?

The intent is to eliminate the need to bring rain gear in addition to my Bivy.

I am amazed that the idea of combining your rain gear and bivy into one piece is not going over well in a place where multi use and ultra light are the professed goals.

(I say this because of two other posts on the subject)

I know it is not useful in some situations like cold heavy wind and rain but for much of the Mid Atlantic summer it will be perfect. Simple and very light.

I can leave it with my tarp in my outside backpack pocket and it will be quick to grab if conditions turn and ready to throw on the ground and climb in with my quilt in camp.

If I decide to stay in a shelter I have wind & bug protection.

What is not to like?

I am a little concerned with the cuben on top of the legs. That might be a condensation trap. Have you considered netting or breathable nylon over the legs?

I have – I have a piece of M50 that I can use on the bottom.

Or I could sew in a panel of it.

Nice thing is I can experiment with it and make changes based on results in the field.

I think it's an interesting idea. The Zpacks poncho groundsheet seems like a fairly well regarded multi-use item as is, and my bivy sack more often than not just gets used as a groundsheet anyway, so coming up with a poncho/bivy could be a neat piece of gear.

The main issue that I could see coming up is how best to deal with the cuben/netting top when using the poncho/bivy in poncho mode. You'd essentially be wearing a double-layered cuben poncho… Would that affect the poncho's ability to vent?

It would add weight, but something like a full length waterproof zipper down the top of the bivy and some loops and toggles along the floor of the bivy would allow you to roll back and secure the two halves of the bivy top to the floor (like a tent door) for use during poncho mode. This would come closer to allowing the poncho/bivy to function like the original poncho/groundsheet.

Anyway, I'll be curious to see what you come up with and how it works in the field.

Excuse the stick figure graphics but I am thinking if i clip down the end edges with say mitten hooks, it will stay relatively in place and not billow about restricting air flow.

Edit: I have been thinking about your idea of a zipper running the length down the center and rolling the sides up at least around the center.

Sorry, I didn't realize that it would actually retain the function of a Poncho after the modification. If it does then you have tremendous piece of multi-use kit. Best of luck! Looking forward to your updated posts with your progress.