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Jared Blank
(jblank4) - F

Locale: Rockies
Bivy Design on 10/14/2009 22:52:10 MDT Print View

Hello to all fellow hikers....

Well, my beautiful and wise girlfriend just bought a sewing machine, hell yeah. So, its time to do some sewin'. Eventually I want to make a nice homemade tarp, but don't have the confidence yet. So i am going to start out by making a bivy sack.
I am familiar with some designs for a bivy sack, ie bathtub or just two identical pieces sewn together.
I was thinking about creating a cylinder type shape for a sack. Sew a tube together big enough for your bag plus alittle more for the loft of the bag and then sew a circular piece to the bottom. It sounds simple enough. Im curious that I haven't seen the type of design in other sacks. Make sense to me, fewer seams. I am just curious if there are any huge disadvantages to this designs. I was wondering if anybody has tested this designs. I am worried about the condensation, though fabric choice might take care of that problem.
I just want to make a solid, easy, simple bivy. Is the cylinder design totally a bad idea or what?

I apperciate the feedback
Thanks to all. And to all a good night

Rod Lawlor
(Rod_Lawlor) - MLife

Locale: Australia
Breathable or waterproof on 10/15/2009 00:41:46 MDT Print View

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.

Jared Blank
(jblank4) - F

Locale: Rockies
Bivy Design on 10/15/2009 20:56:15 MDT Print View

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.

Rod Lawlor
(Rod_Lawlor) - MLife

Locale: Australia
Absolutely on 10/16/2009 03:00:31 MDT Print View

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. www.bookdepository.co.uk/ offers free worldwide shipping, and has it in stock.

Diplomatic Mike
(MikefaeDundee)

Locale: Under a bush in Scotland
Re : Bivvy design on 10/16/2009 03:07:15 MDT Print View

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

Cesar Garcia
(crgowo) - F

Locale: Desert SW
event? on 10/16/2009 11:08:54 MDT Print View

where can you buy event fabric?

Paul Stupkin
(samthedog) - F

Locale: Norway
Event on 10/21/2009 03:52:22 MDT Print View

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.

Cesar Garcia
(crgowo) - F

Locale: Desert SW
Event on 10/21/2009 08:02:08 MDT Print View

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

Frank Deland
(rambler) - M

Locale: On the AT in VA
Momentum 0.90 oz on 10/21/2009 09:29:44 MDT Print View

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.

Franco Darioli
(Franco) - M

Locale: Melbourne
Bivy Design on 10/21/2009 14:11:05 MDT Print View

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

James D Buch
(rocketman) - F

Locale: Midwest
The Book of Bivvy on 10/25/2009 08:18:47 MDT Print View

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

Rod Lawlor
(Rod_Lawlor) - MLife

Locale: Australia
Glad you enjoyed it on 10/25/2009 19:14:54 MDT Print View

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.