Evolution of a MYOG bivy

[Lance M]

After 100 +/- nights in this MYOG bivy I was ready for some design changes:

The bivy was originally designed with a full ‘storm hood’ in addition to the netting. The bottom is silnylon and the top is M90 DWR from Thru-hiker.

Original design:

The storm hood didn’t last long before I removed it:
1. For mostly fair weather backpacking, it wasn’t necessary.
2. It added weight, especially the extra 83” of zipper.
3. Fully enclosed, oxygen level inside dipped to 19%.

After many nights use, the following shortcomings were evident:
1. The perimeter zipper required a lot of body contortion to fully unzip from the inside.
2. When not needed, the netting was annoying. (I should have added ties to hold the rolled down netting.)
3. On a number of mornings, there was condensation in the footbox.
4. On many warm, buggy nights, I could have used more netting and less M90.
5. Inserting my pad and quilt into the bivy was a pain.

So after some brainstorming, here’s what I came up with.
1. Long center zip.
2. Center netting strip similar to Cesar’s and Stick's
3. Shorter cone. 9” tall vs 18’ tall.
4. Wider girth.
5. A little more style.

Initial impressions:
1. Much easier to zip/unzip from inside.
2. Much easier to insert pad and quilt.
3. When unzipped, netting can be pushed out of the way and stays there.
4. More elbow room.
5. 6 ounces in silnylon/M90/nano-seeum and 68” #3 zipper.

-Lance

[todd]

Lance, I love the design!

You really made a good looking bivy – and what makes it look nice also makes it so functional.
Great job on customizing it for you!

[Ryan Smith]

Lance,

That is a thing of beauty. Really love it. How hard was construction? Seems like may have been a bear…

Ryan

[Sam Haraldson]

That is an excellent mod to a bivy. I'd not seen anyone do this before and it seems like a no-brainer. Maintains water-proofness from below, wind resistance from the side, and increases breathability from above.

[Dan @ Durston Gear]

Sweet bivy

[Chad B]

I agree, very nice. I think the center zip is great, I'd like to see more bivy makers either go this direction or have it as an option.

[Jim Colten]

Fantastic, Lance.

That's a bivvy that would enhance any gear manufacturer's product line.

What did you end up with for dimensions (length, foot girth and max girth).

[Lance M]

Thanks everyone for the comments.

'How hard was construction?'

I put alignment marks on the pattern and transferred the marks to fabric with 'V' shaped snips so aligning the pieces was easy.
However, I used the same 3/4" seam allowance I've used on other projects and that was a mistake. Folding/rolling the curved seams, even with the flimsy, stretchy fabric was very tedious. On the head end of the silnylon floor I ended up trimming back the excess seam allowance with a rotary cutter after the first line of stitching but before rolling/folding. Next time I'll use a 3/8" seam allowance on the curves to make rolling the 'modified' flat felled seam much easier.

'What did you end up with for dimensions (length, foot girth and max girth).'

Floor length is 78". Foot box is 12"x18" (60" girth). Shoulder girth is 76" plus 2" attributable to the cone.

-Lance

[Jake D]

Thanks Lance for sending me the pattern for his bivy design!

ordered the sil 2nds and mesh from Quest and the M90 and zipper from Thru hiker. Hopefully my gf will give me a hand with the sewing since i've only done quilt/mittens and she has done our tarp tent with mesh and more construction.

i'll keep ya updated once it gets going

[Tim Skidmore]

I'm about to sew on the noseeum top on my latest bivy project, I have the zipper on the side but i was considering moving it to the center like you and the MLD bug bivy have done.

Now that you've had it for a while, do you still like it there?

[Jerry Adams]

I've been using center zip bivy for years and think it works pretty good.

When you don't need it zipped up – no bugs and warm – both sides tuck out of the way nicely. Or when you're getting in or out.

[Cesar Valdez]

NOOICE!

(https://youtu.be/rQnYi3z56RE)

But seriously, that might be the best MYOG bivy I've ever seen–though I am a bit biased about the design ;)

I love the whole thing though! The top entry I think might operate slightly better than a side zip, and mos def better than those bivies with just the little slit across the top.

[Jason Johnson]

Can I borrow it for my JMT?

[Author]

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