Cuben/Momentum Bivy

Where did you get the Cuben and Momentum from?

You can buy Momentum from Thru-Hiker and 0.6 Cuben Fiber from Zpacks.

Johann,
Momentum is from Thru-Hiker, and Cuben is from Quest Outfitters…as Matt mentions, there are a number of different resources with the same product.
Steve

Off topic: Matt, did you do a follow up on BPL about your trip? I couldn't find the original thread you posted.

Did you do any seam sealing?

Johann,
I did not seam seal the bivy. I don't see it necessary as I will use this with a poncho/tarp and I always use a closed cell pad (GG 1/8" thinlite) as a ground sheet. Short of rolling into a puddle of water (poor site selection), you would be hard pressed to have water enter the bivy. I haven't sealed any of my other bivys and have been good so far…but I guess we'll see.

I love it. I'm contemplating something very similar, but will probably add a short zip. Excellent seamtressing!

Wow, this has to be the lightest bivy I've ever seen. I'd be interested to hear some notes from the field on this.

Your Bivy looks real nice.

I made my Cuben / Pertex Quantum Bivy back in 2006 and have a thread here.

Finished Bivy:

Bivy with a long balloon to hold the hood up.

Cuben / Pertex Quantum Bivy Thread

I have a BPL.com Vapr Bivy and made my Cuben / PQ Bivy the same size. It weighed 2.68 ounces but then I added some snaps inside the Bivy to connect to a Climashield Combat Quilt. This increased the weight to 6.82 ounces.

I have used the Bivy /Quilt a lot and one night down to 42 degrees and was nice an warm.

On the ground in Georgia, October 2006.

Excellent seamtressing!

Thanks Allison, I'll pass it on to my mom. :)

Haven't taken out in the field yet, and probably won't until the weather is nicer, but I'll let you know.

Bill,
I saw your bivy a few years back. Nice work…I assume you used the .33 oz/yd cuben? How is it holding up?

Hi Steven,

The Cuben I used was the 0.32 / 0.33 ounce per sq yard version.

I use it with a light ground cloth for insurance and to help keep it clean.

It has held up very well. I used it a few nights ago to take a nap in my backyard when the temperatures went down to about 30 degrees. The Bivy is just big enough so I can get my sleeping pads inside it or my Warmlight Down Air Mattress along with another quilt when necessary.

I need to made one or two more Bivies and I am way behind on getting them finished.

Steven and Bill:

Can you guys give me a ballpark estimate on how much it cost to make your bivy's?

Thanks in advance.

Erik,
I think I paid about $25/yard for the cuben and $15 for the momentum. I bought a role of thread from thru-hiker a while back but can't remember how much it was…maybe 10 bucks.

I used a little less then 3 yards of cuben and less then 2 yards of momentum.

You could invest $115 and make this bivy, and then have some material left over…but it took my mom and I the majority of a day to trace, cut, and sew it up – I'm sure we could have done it faster if we knew what we were doing :)

Erik,

I bought my Cuben direct so at that time it only cost me about $17 a yard. I did have to buy 9 yards at a time.

The Pertex Quantum cost about $16 a yard and I had to buy 5 yards. This was back around 2004.

Add these two items and both my Bivy and Steven's Bivy are about the same cost.

The problem today however is that Pertex products can not be sold retail.

I have always said when asked that I would use Thru-Hiker Momentum as a direct substitute if / or when I run out of Pertex Quantum.

You may think $25 a yard from Quest is high, I just bought the min.9 yards of the 0.33 ounce material and paid Cuben $25 for shipping and Handling on something that only weighed 3 ounces. That is $2.77 a yard for shipping from Cuben. Quest is paying a high rate for their shipping just like I / we have to.

Appreciate the information guys. Very interested in this project and your photos and comments help!

It looks like in both Steve's and Bill's bivys that they are two flat pieces sewn together, with an additional piece for the hood. Did either of you consider making a bathtub-like floor for your bivys?

This would keep seams off the ground, but I haven't figured out how to do it exactly without cutting, yet. I can do it with a square/rectangle, but the bottom is mummy shaped. Thanks.

Hey Matt,
This was my first bivy (I didn't even sew it, my mom did) so I wanted to keep it as simple as possible. You'll have to let Bill or someone else chime in to get exact directions on how it is done. I have an idea but don't want to give out an incorrect (or more difficult) technique. :)

I'll be looking forward to a response aswell.

Hi,
==
"Did either of you consider making a bathtub-like floor for your bivys? This would keep seams off the ground"
==
Yes, but I use a GG very light ground cloth to help protect the Cuben bottom on my Bivy so it isn't necessary. I also use that Bivy in my Hammock so I am not on the ground that much. Sliding in an out gets easier with practice.

The main reason I use Pertex Quantum as the top piece is to help dry out my cloths over night if they are damp.

I could make an "all" Cuben Bivy with a venting option on the foot end that should weigh under 2 ounces.

Matt,
I made my Cuben/Momentum bivy with a bathtub fllor and no seams. Just folded up the Cuben corners so I wouldn't have to worry about seams and leaks. Here is the old thread.

http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/7584/index.html?skip_to_post=54680#54680

Kevin

Thanks! That is exactly what I was thinking about. It just wasn't working conceptually in my head. Great!

(That said, I just got an MLD Superlight from the Gear Swap, the exact bivy I was looking at. Shipping today/tomorrow. I'll file this one for later use.)