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First Project - Cuben/Momentum Bivy
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Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
First Project - Cuben/Momentum Bivy on 05/03/2007 18:47:31 MDT Print View

After seeing all the great things everyone else has been making, I decided to jump into the fray and try my hand at making something I needed. Decided to make the bivy after seeing Bill's superlight bivy. I took his concept a little further and actually built a Cuben sleeve into the upper portion of the hood to firmly hold a balloon. Wasn't sure how well this was going to work but it actually holds the hood up easily and securely. I think the trick is to make sure the balloon is fully captured in the ends and middle. I decided to make the sleeve full length since the Cuben is so light, I also sewed in the noseeum into the hood and figured I would just tuck it in if needed or fold it back if there are any bugs out.
End view of new bivy
Bivy opening with balloon in sleeve
Final weight ended up being 5.4 onces. Since I have a lot of Cuben left over, I'm going to take a shot at making some rain chaps and even a shelter now. I got the MYOG bug ... THANKS.

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Cuben/Momentum Bivy on 05/03/2007 19:31:46 MDT Print View


Your Bivy looks great and I really like the Blue Momentum. Is that from

David Goodyear
(dmgoody) - MLife

Locale: mid-west
wow looks great on 05/03/2007 19:38:08 MDT Print View

did you use a pattern? I've been considering a bivy as my first project. What was the difficulty level?

any help would be appreciated.



Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: Cuben/Momentum Bivy on 05/03/2007 20:01:57 MDT Print View

Bill, yes the Momentum 90 was from Thru-hiker. It seems like really nice material and for a first time project I actually thought it was easy to sew. I ended up using the 1/2 inch wide 3M tape that I cut in half to hold everything in place prior to sewing and to also make the needle holes waterproof. The only downside is having to clean the needle when ever it gets to gummed up from the tape, about every three to four feet of sweing. Thank you Bill for all your great photos and write-ups. Saved me a LOT to time and thinking by being able to read and see what you have done. Your idea on using the balloon seems to really work well!! Can't wait to try it out in the field one weekend soon.

I purchased a large roll of 50 lb brown wrapping paper and made all my patterns from it. I just laid my sleeping bag on the paper and then figured out what the size should be. I ended up being able to fold every seam on the Cuben bottom portion so there isn't a single stitch that could leak. I then transfered all the line to the Cuben and used the tape to hold the folds in place until I connected the top Momentum with tape prior to sewing. Not sure if that makes sense ?? I really took my time and thought threw everything BEFORE sewing. I think the key is making all the paper patterns and actually taping them together to make sure it works before doing any cutting and sewing.Bivy pattern at head
Bivy pattern at the foot

Edited by kegelhoff on 05/03/2007 20:04:25 MDT.

kevin davidson
(kdesign) - F

Locale: Mythical State of Jefferson
A fine Cuben/Momentum Bivy on 05/03/2007 20:36:41 MDT Print View

Looks great and well thought out.

Couple of comments: Wouldn't a seperate worn mesh headnet be lighter and just as effective? That's a lot of mesh material you're using. Secondly, many Bivy makers make what I think is a mistake--- the waterproof bottom of the bag is brought up too high in the foot section, making it more condensation prone. One maker of bivy sacks has experimented both w/ using a drawstering opening bottom or by using a foot end made of eVENT to reduce condensation.

Again, that's a great MYOG !

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: A fine Cuben/Momentum Bivy on 05/03/2007 21:39:10 MDT Print View

Thanks Kevin.

I'm a really light sleeper and can't sleep with anything touching my face, hence the balloon to keep the top and netting off my head and face. You are correct about all the netting being too heavy but I couldn't think of a lighter method keeping it off my face. I figured it would be lighter than sewing in a zipper and making the netting smaller ?? I'm still thinking though and can easily remove it if I can think of something lighter and better ??
Also, you can't tell in the picture but the foot end of the bivy is almost all Momentum 90 going over the top and down the bottom to about 2.5" from the bottom. I figured maximum breathability. I considered using the drawstring as others have talked about but I have never really had a problem with overheating. Time will tell.

Edited by kegelhoff on 05/03/2007 21:42:59 MDT.

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
First Project - Cuben/Momentum Bivy on 05/04/2007 09:26:02 MDT Print View


It's excellent to see the balloon technique work so well for you. The quantity of mesh may be slightly heavy but in my opinion it will be extremely helpful in the breathability of the shelter.

- sam_h

Devin Montgomery
(dsmontgomery) - MLife

Locale: one snowball away from big trouble
Re: First Project - Cuben/Momentum Bivy on 05/08/2007 23:21:11 MDT Print View

Nice bivy, Kevin. That's quite a first project and an amazing finished weight. Once you trail test it, I'd like to hear how the Cuben stands up to this type of use, and how you like the balloon hoop. I think that's a particularly keen use of "no more than is needed" weight savings.

Cameron Reed
(cameronjreed) - F
How does it close on 05/17/2007 16:37:35 MDT Print View

From looking at the pictures I cannot tell how the bivy closes (in the event of bad weather) I see a drawcord in the middle of the top opening. Is that used to close it? If so, how?
You didn't use zippers, did you?
Just curious. I am thinking of making a bivy, but do not want the fuss of putting in a zipper, but I still want to have good weather protection.

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: How does it close on 05/17/2007 18:00:15 MDT Print View

You are correct. The drawstring will snug up the bottom portion of the bivy. The top portion of the hood actually overlaps the bottom portion by about 4.0 inches. Not enough to keep rain from coming in with the hood up in the air using the balloon. If the balloon is removed, I think it would overlap fine but I don't have a system to secure it. This won't be a problem for me though as I always use a bivy under a shelter so I just need some basic protection from moisture and bugs.