MYOG Bivy

[Stephen Hoefler]

Hi Dave,

The new bivy pattern should be a little bit more roomy than the previous version however, I do think it would be a good idea for you to expand the foot box by a few inches.

You might have seen my post earlier with the bivy and neoair. I adjusted the measurements to be a bit more roomy to accommodate the neoair and sleeping bag.

Before, the measurements on the bivy were:

<–11.5"-M90–><–6.5"-bug net–>Zipper<–73"-M90

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> (top of bivy lengths)
Head: 25"

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Zippered Middle: 36"

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Foot: 25"(width of bivy)
<

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17"

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><

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73"

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> (bottom of bivy lengths)

The new dimensions are…

<–12"–M90–><–7"—bug net–>Zipper<–72"-M90

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> (top of bivy lengths)
Head: 29"

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Zippered Middle: 36"

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Foot: 25" (width of bivy)
<

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18"

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><

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72

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> (bottom of bivy lengths

MY dimensions for the Neoair bivy where as follows…

<–11.5"-M90–><–6.5"-bug net–>Zipper<–73"-M90

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> (top of bivy lengths)
Head: 35"

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Zippered Middle: 36"

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Foot: 28" (width of bivy)
<

---

17"

---

><

---

73"

---

> (bottom of bivy lengths)

I found that with the extra width at the foot, I could fit the neoair and sleeping bag snuggly. I don't think the neoair would have been so cooperative if I had used the original dimensions. Also, I wouldn't recommend folding in the corners anymore than 8" to achieve extra height, doing so will make your bivy too narrow for the boxy neoair. The extra room at the head had nothing to do with the neoair, I just wanted more room to stow things away with winter use in mind.

Let me know if that clears it up for you!

[Dave Holst]

Cheers Steve,

So what height did you use at the head and foot ends of the bivy? 8"? Thanks for your dimensions! I will be using my bivy bag with a neoair all the time so based on the "snugness" would you recommend adding a little width for height, or was it not too constricting around the feet? Will hopefully have a crack with this next week :)

Dave.

[Stephen Hoefler]

Hi Dave,

Yes, just the 8" called for by the instructions.

I'm not sure how wide you'll need to make it. I suppose it mostly depends what you'll be using for insulation on top of the neoair. For reference, in that photo, I was using a Feathered Friends Hummingbird which is a 20F sleeping bag with a minimal footbox. When inside the bivy with sleeping bag and neoair, the bag was pressed up against the walls but there was still a small amount of wiggle room. I don't think that's necessarily a problem, but I wouldn't want it any tighter. It seems like some vacant air between the bag and bivy helps to reduce condensation and to some degree increases thermal efficiency by allowing the bag to freely loft.

Making the bivy was a pain free experience for me! Make sure to use LOTS of sewing pins to keep the material together. Silnylon and M90 have a tendency to be quite slippery and difficult to sew if you don't pin them down. A walking foot will also help if you can find one for your machine. The only tricky part for me was making the foot box look symmetrical and pretty. I'd recommend getting familiar with making this ->(http://thru-hiker.com/projects/silnylon_stuffsacks.php)<- stuff sack because that's the way you'll form the footbox. Everything else was quite intuitive.

Best of luck!

Cheers~

[MFR]

A big thanks to everyone on this thread–Chris and Jamie in particular. As a belated Valentine's Day present, my wife sewed me a bivy! The top is M90 (over M50 for the added breathability) and Shield silnylon, and it came out to 6.7 oz (with seam allowances double-stitched for added strength). She finished it about three weeks ago, but I decided to add a line of stitching along the zipper to keep the M90 from getting caught. So–technically–it wasn't finished until this morning. Regardless, I am a lucky man.

I decided I wanted it to be a little roomier because I use an inflatable, have large feet (size 12), and to keep the option open for fitting a winter bag. I ended up expanding the dimensions as below. Honestly it has a lot of space. The only thing I'd change if I could do it again is the netting window. I lost more of the M90 to the head wall than I expected, and I could definitely get away with a smaller window. Other than that, it's exactly what I wanted.

Here are the adjusted dimensions I used along with obligatory pictures:

[Steve C]

Clayton,
What is your height and approx. weight? Just trying to visualize how I would fit into those dimensions. Thanks,
Steve

[MFR]

Hey Steve–I weigh about 220 and am 5'11" with a 46" chest and a 36" waist. Actually, here are a couple of pictures of me in the bivy. I'm using a NeoAir XLite size Regular and a GoLite Ultra 20 down quilt. They're cell phone quality and not as pretty as the DSLR pics, thus the reason I didn't include them originally.

Are you interested in making one yourself? Even though I didn't sew this one up, I watched my wife do it pretty constantly (she had to make me leave the room and do something else), and it was definitely easier than the tarp I just finished. The only thing tricky would be getting the curve of the zipper right (she really did an excellent job there).

[Steve B]

Just finished mine; head 30", foot 28" (to accommodate a full length 2" thick pad) , with 7" of bug net. 8" tuck at the foot end, 6" tuck at the head end. Used 0.75oz cuben for bottom, Impetus 1.1 for the top.

I'm very impressed with the feel and breath test of the Impetus, very nice fabric. If I try to make clothes I'm using Impetus. No tacky feeling like some of the M50 fabric I have.

Quite a long side zipper, longer than 24" (don't have a length at the moment). Weight came in a 4.8oz, but I did forget to add stake out loops. Guess I can add them if they end up being needed (are they?).

Kudos to Jamie Shortt for the pattern and all the contributors of this thread. Sure does add to the confidence when starting a project!

Steve

[Aaron Sorensen]

I really like how the Impetus 1.1 fabric doesn't settle on top of your bag.
It is a stiffness to it that lets it trap air in between the bivy and bag.
That is very important in repelling water and keep it from getting your bag wet.

[George Tate Hunt]

Thanks to all who have added your voices and images to this thread. I am in the process of making this bivy, and went about the design you all have contributed to above. I used fabric pattern paper to create a sewing pattern for cutting out the silnylon bottom, and Impetus top pieces. I pinned the paper pattern to the fabric in the seam allowance, and was able to cut it all out with a rotary blade, while moving my cutting pad up and down the pattern. I candle sealed all my edges and am ready to start sewing. I will be using a walking foot attachment to help feed the slippery fabric evenly. Question: What is the assembly order you all used when sewing it all together? Did you piece together the top pieces add zipper, and then sew top to bottom right sides together, sew your box corners, then turn it all right side out? I read through all the posts, but didn't really see anyone posting the sewing steps. I am sure I can figure it out, but was hoping to avoid any unnecessary errors. Did you do flat felled seams down the sides or simple roll seams? Did you roll and finish the box seams after cutting away the excess fabric corner? Thanks!

[Steve B]

I cut out the bottom, cut out the lower half of the top, sewed excess netting to excess head impetus, then cut out top half, then sewed zippers, then sewed to the bottom. I hot cut everything, so I did not roll any seams (just lay it over and sew again). I might regret that, but I doubt it. Yes, cut off the excess in the box corners then sew down the hem.

Hardest part was the zipper. Lots of thinking to get it looking right, especially in where to cut the zipper off. I melted part of the zipper together to stop the pull from coming off (used solider iron)

Steve

[Jerry Adams]

You can just hand sew a bunch of loops of thread around zipper, between two zipper teeth, to keep zipper pull from coming off.

[Mitchell Ebbott]

I just finished making my bivy based on this design! I used Silnylon for the bottom and Tyvek 1443R (the soft type used for clothing) for the top. It's very water resistant, near waterproof, and quite breathable. The only downside is durability, but I don't anticipate any problems so long as I'm attentive. Also, I already had a big piece lying around (was previously using it as a groundcloth) so it saved me about $30 over Impetus or a similar fancy fabric.

Weight is 7.3oz, and I made it a bit roomier than the instructions called for.

Total cost: $26.50 shipped for Silnylon 2nds, noseeum netting, and a zipper. I think the Tyvek would have been another $10 had I bought a new piece.

Here are some photos:

[Jeff McWilliams]

Looks good, and the price you paid for materials is hard to beat! Where did you source your materials from?

What sort of pad or mat do you plan to use with your bivy?
How much foot room do you have when lying on your back? I wear a size 13 shoe/boot when hiking. I've been working up to making a bivy based on this design, but I may have to make more room for my feet.

Are you a side sleeper or do you sleep on your back? I'm an active rotisserie sleeper, so again, having enough room to toss and turn and sleep on my side are important to me.
Also, I plan on using a NeoAir XLite in mine. Bad back needs the comfort.

[Mitchell Ebbott]

I got all the new materials from DIY Gear Supply. The Tyvek was from Into The Wind.

Those photos are with an REI Flash inflatable pad. Pretty comparable to the NeoAir, but mummy shaped. The fit is okay, but if I were to do it again I'd make a little more room in the footbox. It's not quite so tight as to compress my sleeping bag's insulation, but it's close.

It's only the foot area that feels tight though. I'm not exactly a peaceful sleeper myself, but I think I'll be fine with the shoulder room. The hood area is actually a little too big, but that gives me space to stash things.

Be forewarned though, I didn't stick with the exact dimensions of the plan. Since I was using an existing, already cut piece of Tyvek for the top, I expanded the bottom dimensions with the intention that the silnylon would come further up the sides than the Tyvek. I think I ended up with something a little bigger than the plan called for, but I can't be sure.

[George Tate Hunt]

Will try to get some better photos. Made with Silnylon and Impetus, used the double zipper others employed here. Made it a bit wider for the air pad, and extended the bug netting a bit more than the original design.

[Derek Weeks]

I have a question about everyone bivy that they made. My question is are the dimensions (pattern) for bivy at foot 25"and head 29" is that before you fold in the corners and sew 6"? I was wondering, because I'm making a bivy now, but wondering if i need more or less room.

Thanks!

Derek

[Dave @ Oware]

Depends on the width of ground pad. 25"-6" leaves 19" width for your pad. This would likely work for a 20" pad, but a full length 24" pad may not be roomy enough. Also depends on the girth the rest of the bivy and the top panel.

[Derek Weeks]

Awesome thanks David! I cut the fabric last night and made the pattern at the head 48" and at the bottom 39" (8 inch walls) so that should work for my pad. After I cut the fabric I started freaking out that I may have made a mistake not having enough fabric to folding ends, but now think it will work.

Thanks again for the help!

Derek

[Derek Weeks]

Just finished my bivy tonight and have to say quite happy with the way it turn out. The bivy is 4.1 oz and big enough to fit my 2.5 inches sleeping pad and quilt. The bivy has 8" walls .51 cuben fiber and top is .75 oz Pertex GL Ripstop Nylon from Zpacks.

Thanks everyone for the posting on here and thanks for those for all the great ideas. Thanks to Jamie answering emails. And thanks to Andy from Sea to Summit Ultralight blog for all the great info!

Derek

[Michael Orth]

Nice work that looks sweet!

[Mario Caceres]

First of all, I want to thank all those that have shared their insights on this thread, all those posts have been extremely helpful in my first attempt at sawing a bivy. I though I would add my experience since I have deviated a bit from previous posts (I think the beauty of making your own gear is to be able to customize its dimensions, etc).

I basically followed the guidelines posted in this thread (I.e boxed corners, horizontal netting at face level, etc). What I did a bit different was:
1) Closing: I put a zipper running lengthwise along the middle of the bivy. I think this makes entering / exiting the bivy much easier. The added weight would be marginal if you consider the total length of having a zipper across the chest plus a side zipper.
2) I kept the girt of the bivy wider from shoulder to hips. (i.e 8 sides instead of 6 sides). This is similar to what Joe at Zpacks is doing with his splash bivy.
3) The walls have a larger section of waterproof material than beathdable (8” silnylon + 2” argon). This made the construction a bit more difficult but not too bad.
4) I put tie outs in the corners and on reinforcement patches where the zipper ends. Not sure I will actually use the corner tie outs but I though it would be much easier to put them on at the time of building the corner seams that trying to add them on later. Their weight is negligible.

Again I'm not very experienced at sewing so I found it very useful to baste all my seams before the actual sewing. This was time consuming but made it much easier to sew the actual seams on a slippery material like silnylon. To figure out the dimensions that would work for me, I did first a full size mock up with an old sheet I bought at a Goodwill store. This was very helpful to make some adjustment of the size of the final product (this is when I realize having a larger girth at the hips level was beneficial). Sawing a mock up on an easier material like a cotton sheet also allow me to get a little practive before I transitioned into a harder material to work with like silnylon.

Here are some basic info on my bivy:

Materials used:
Top: 0.67oz/yd Argon (From Dutchwear Gear)
Bottom: 1.35?oz/yd Silnylon (Actual weight more like 1.7 oz/sqyd) (Seconds from Oware)
Netting a Face level: 0.7oz/yd ultralight insect netting (From Zpacks)
Zipper: 56” #3 Zipper with double tab
Thread: Gutterman Tera 70
Needle: Schmetz Microtex 70/10

Measurements:
Top Girth (Head): 64”
Shoulders Girth: 78”
Hips Girth: 78”
Bottom Girth (Feet): 64”

Length: 90” (Laying out flat)
Walls: 10” (8” of waterproof, 2” breathable material)
Netting at face level: 9" strip

Total weight came in at 7.8oz. This is much heavier than what I was hoping. The silnylon I used was definitely much heavier than it's nominally spec'd weight (1.3 oz/yd). I weighted that part alone before assembling and it came in at 5.8 oz, so based on the dimensions I was using the actual weight of the silnylon was more like 1.7 oz/yd). I hope this means I have a more durable bottom. Overall I'm fairly happy with the final product. I will be testing this bivy next week on the field and will be able to report on the breathability of the argon 67.

I will be using this bivy with a Medium Exped synmat 7 mattress (which measures 22” x 72” x 2.8”, actually Exped shows 20.5” width in their website but mine measures 22” inflated… not sure if they have changed their width specs since I got mine).

On this pictures I have a Western Mountaineering Versalite stuffed with some small pillows to simulate a person inside. I hope this helps.

Edit: Pictures added

[Joost D]

Hi all,

I now this is an old thread but I have a question about the boxed corner.

I want a bivy with the same size as an astucas bivy. That’s 235cm long (I’m 197cm).
And a girth of 210 and 160cm
How many cm do I need to add for the boxed corners?
Regards Joost

[Joost D]

I use a klymit insulated ul pad and. 7,5 oz apex quilt btw.

[Jerry Adams]

Maybe for 210 cm circumference – 60 cm wide, 45 cm tall. A 22 inch wide mattress (56 cm) would fit into that 60 cm width.

Maybe for 160 cm circumference at the foot, 50 cm wide and 30 cm tall?

I just make my bivy rectangular – same circumference at the foot end – more room to move my feet around to find a comfortable spot.

 

[Joost D]

How do I calculate the boxed corners for the head and footbox.

Like the idea of a rectangle bivy btw. Weight penalty would marginal but does mean more comfort.. ;)

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