Bivy Design

The only issue I see is whether to make it breathable or waterproof. Using one piece of fabric will only let you choose one. Adding just one more seam, down the other side, lets you;
Have a waterproof floor and breathable top
Easily taper the shape from shoulders to feet
Increase your girth from 58" up to 116" if you like
Use simpler shapes in cutting

Having said all that, if you try it as a tube, and then decide it isn't great, just unpick the seam, and use your fabric as either the top or the bottom of your new design.

Rod,
Excellent point. I apperciate your feedback. That seems to be the norm with bivy sacks, waterproof bottom, breathable top. I imagine it is still possible to do the tube design with two different types of fabric with some creative sewing.

Can anyone think of any other disadvantages to the tube/cylinder design.

I am not opposed to the other designs on the market. I kinda just want something different, maybe original.

Thanks to all.

Jared,

If you add that extra seam in, there's absolutely no reason not to go ahead and use your tube design.

If you haven't used a bivvy before, consider picking up "The Book of the Bivvy" by Ronald Turnbull. http://www.bookdepository.co.uk/ offers free worldwide shipping, and has it in stock.

You could make a one seam 'tube', or tapered 'cone', if you made the bivvy totally from a W/B fabric like Event.

where can you buy event fabric?

Hello Cesar,

I think you will have a real hard time finding Event. I would probably go for epic. You can try these guys:

http://thru-hiker.com/materials/breathable.php

They seem to have a pretty good range of materials at a reasonable price. Good luck.

P.

Thats what I thought but since Mike mentioned making it from Event I was wondering if he knew where to get some.

Momentum .09 is a nice breathable top from thru-hiker. Nice color choices, too.
Maybe you could not sew the one tube seam on your WP fabric all the way up, maybe only half way, or slightly less than half way. It could be used with the opening on top or on the bottom. You could add a few ties so it could be tied together if you wanted to close it. It would leave you with ann option for venting.

Most fabric is available up to 60" wide. Are you sure you can get this kind of fabric 80" or so wide ?
Franco

Rod,

Your suggestion to pick up "The Book of Bivvy" by Ronald Turnbull was excellent.

I greatly enjoyed it, and learned quite a few things.

Jim

Thanks Jim,

I'm glad you enjoyed it. I liked it so much I had a copy sent out to a friend. It's convinced him to ask for a bivy as a Christmas present from his wife and kids.

Turnbull does have the true UL spirit, including his ideas on ducking out for a 24 hr trip.