Perfect bivy?

I made one sort of like that. Basically a tyvek tube, split down the left side with an overlap. The long top part goes up to about your neck. The head part is the tent type and extends down a bit for coverage., planned to be held up by 2 stadium ballons. That works.
It too is split on the left side about 12" with some velcro tabs.

I never figured out the netting, but velcroed on for sure.

I stopped when I realized it was not big enough to get my neoair in, now that I have a quilt. Neat thing about tyvek is you can just glue it together.

The next one will be a tyvek top and a cuben tub.

I might try to do a sketchup of it and post.

Picture:

Maybe i'm missing something, but the base wouldn't be waterproof.

Top: quantum or similar.
Bottom: Silnylon or cuben.

I don't sleep on too wet palaces, so holes in to bivy bottom is okay. Pad is outside of bivy.

I try to draw picture, but i make things not draw things… Perhaps this picture says more than 100 words.

Why not put the opening on the top?

Yeah, seems like it'd be hard to get into the sleeping bag with the bivy entrance on the bottom.

This reminds me of a quilt-inspired bivy, with the velcro holding the bottom together. Getting in would be best accomplished by sitting on pad and sliding bivy onto feet and climbing in. Getting out for a midnight call of nature might prove cumbersome. As one who struggles w/ tent zippers sometimes at night, I don't think I would go this route. How about a flip top with Quantum/Mesh flaps secured with velcro. If weather/bugs cooperate just sleep w/ flaps open. Getting in and out would be similar to your exisiting draw cord bivy minus the draw cord.

The slit should go on the side IMO with a tub floor.

Hey Timo,
Everyones idea of what the perfect bivy is will be different. I like your idea, but like others think the slit should be on the top – of course you are welcome to make it however you like.

I have been toying with the idea of a center zip bivy for a while now. i have the material on hand, just never got around to making it. I think they would be easier to get in and out of.

Let us know how yours works out.

Since you asked, my idea of a perfect bivy:

* 1.5 ounce/yard cuben fiber bathtub floor for total waterproofness without the need for a groundcloth.

* Whatever highly breathable water resistant top is lightest

* half zipper for easy entry

* full bug hood similar to tigoat ptarmigan

I'm guessing it would come in at 7.5 ounces or so.

How do you prevent rain from coming through the mesh?