During the colder months especially I use a very thin evazote mat 2m long by 0.75m wide to augment my torso length prolite 4. It occurred to me that the bottom of the bivy stayed bone dry on the mat and I only needed the bivy to protect from a little misting and brushing against the walls of my single skin shelter.

Here are a couple of interpretations I whipped up in sketchup quickly.

By entering the bivy from beneath weight could be saved by not needing zippers as the hole could be kept snug with an elastic hem or lightweight draw cord.

I realise that this design would have limitations by not being able to use directly on the ground but if you use a groundsheet anyway then why carry a second?

Any gaping holes in the design (Pardon the pun) I'd love to hear them or suggestions how it could be impoved.

Ta, James

Edited by JamesCavan on 06/01/2011 07:43:58 MDT.

misread your wording thinking you have no pad where the hole was.

Edited by jshann on 06/01/2011 08:04:13 MDT.

I like your thinking.

Ryan

James,

Quite an intriguing idea!

This is what would be called Thinking outside of the "Bivy".;-)

The way that you describe entering your bivy is the same method that I use to "don" my top quilt.

I pull the quilt over myself, insert my feet into the footbox, sit up and put my head through the drawstring cinched / snapped together opening and then lie back down. Just a little side to side rolling is all that is required to "tuck" the quilt under my body.

Am I doing the math correctly? When I convert .75 m to inches I come up with approximately 30" in width for your pad. Is this correct?

With that kind of width staying on your pad during the night shouldn't be to difficult.

Party On,

Newton

James,
Thinking out of the box on this Bottomless Bivy . Getting in out would be hell like fighting your way out of wet paper sack in less you make the head end and foot end less than 18". So you can slip your feet and head in easily then you have to tuck each side under you.

I would think instead of a hole entrance just have a bivy blanket with 24" head and foot area only to slip your head and feet out of have over large sides that hang down on each side . Kind like getting under the blanket of your bed.
Terry

Newton - Yes the thin pad is 30 inches wide! Some might consider it excessive but it gives me some wiggle room to get comfy on the ground! Plus i can put things head torch and other bits in easy reach in the night out of the dirt and wet.

Terry - Ideally the edge underneath should be as small as possible, or alternatively like you say a blanket type affair. The downside I can see to that would be wind creeping under the edge - maybe a drawcord around the hem would have the desired effect of bringing it all in or used as a blanket.
There's maybe a more accurate idea of the bottom opening

Edited by JamesCavan on 06/01/2011 09:31:12 MDT.

bivy

Link above shows a bivy made by Steve Evans. (scroll down page on right) It has a single 36" zipper centrally located for getting in and out of bivy. If you turn his bivy upside down the entry could be used as you are contemplating.

I've fooled around with this design a bit on my one person tent. I'm not very flexible and find that a 4' long opening is a lot easier for me to use.