hybrid bivy/quilt

[Jerry Adams]

Hybrid quilt/bivy

I’ve made several versions of this hybrid bivy/quilt over the years, made refinements, slept in it for many nights. Maybe there are some ideas here that would be useful to others.

It weighs 22 ounces. The outer fabric is M50 from thru-hiker, 0.7 osy. This fabric has a good DWR that resists dew and mist, but if it’s raining I put up the tent, M50 won’t protect from rain. It’s good if it’s windy. I always use a polycro groundcloth for waterproofness.

The bottom is a 1.5 inch bathtub floor, 6.5 feet x 20 inches, with a tapered end down to 10 inches wide. On top of that is a sleeve – 6 foot x 20 inches with tapered end. My uberlite goes inside. The uberlite is 2.5 inches high, which fits into the 1.5 inch deep bathtub because the uberlite has rounded edges. Actually, it barely fits, I should have made it a 2 inch deep bathtub. But then I decided the uberlite has a slow leak, have mostly quit using it, and use a 1 inch high Prolite which works great. If I wanted to use a 3 inch mattress, I’d make it a 2.5 inch deep bathtub.

The reason for the sleeve is because when I sit on the uberlite, the end bends up, the horizontal baffles bend like hinges. With the sleeve, it constrains this. But now I don’t use the uberlite much so I could do without the sleeve. I slept directly on the prolite for years without problem. If I was going to make it again, I don’t know if I’d put a sleeve in. Actually, it doesn’t make much difference one way or the other. The sleeve adds 1 ounce.

I made this with 0.7 osy rsbtr breathable nylon. In the past, I used silnylon, which is 1.25 or 1.5 osy, but with the polycro groundsheet, the floor doesn’t need to be waterproof. Also, the air matt is waterproof. So I just used breathable nylon to save a little weight.

On the 4 corners I put short guylines which I can stake out to keep it from blowing away.

quiltd1

I then have a quilt sewn to the top. I use M50 on the top for it’s better DWR to keep dew at bay, and rsbtr nylon on the bottom for better breathability. The rsbtr DWR is probably just fine, the M50 isn’t necessary. I have 4 inch baffles (1.75 inch loft) on the head half, and 3 inch baffles (1.325 inch loft) on the foot half. 10 ounces of 850 fill down, which is about 30% overfilled. I used asymmetric sewn through baffles but you could use strips or even regular sewn through baffles. Or you could use synthetic.

The quilt is 20 inches wide, 14 inches high, 6 feet long. The bottom half is tapered down to 10 inches wide and 8 inches high. The total quilt width is 48 inches.

Regular quilts are wider, and then tucked under you on both sides to minimize drafts. Sometimes they have straps to keep away drafts on the edges. Having a bottom of fabric provides better draft protection and allows the quilt to just come down to the edge without any being tucked under you. Having the mattress inside, with the corners guyed out keeps this all in place so when I roll over, the edge of the quilt stays next to the mattress so there are no gaps and cold spots.

At the center of the quilt, going half way down from the top, there’s a #5 coil zipper. If it’s warm, I’ll just leave the zipper open so I don’t over heat, and then zip it up if I get cold. With the center zipper open, I just tuck in the edges to the side. If there was a zipper on one side, unzipped, the side of the quilt would tend to go into the dirt, and at the zipper, dirt would tend to get kicked inside.

Along the top I have a 1/8″ elastic cord in a sleeve with a cord lock. Shorten the elastic until the top is against my neck. I can move around a little which stretches the elastic.

I have used this comfortably down to about 40F wearing just long pants, long sleeved shirt, and hat. I’ve used it down to 20F when I add synthetic vest (3.5 osy apex) and a down vest (3 inch baffles, 1.25 inch loft, 9 ounces).

quiltd2

After using this, I decided it was too short, I couldn’t point my toes. So, I removed the 8 x 10 inch end, added 2 baffles that are 3 inches wide, and put the end back on, so it’s 6 inches longer. No pad underneath, but there is down. I could have just made the quilt 6 inches longer.

Another problem I had, there was a huge gap around my shoulders, horrible drafts, so I added a triangular piece on both sides. 13 x 20 x 24 inches. 3.5 osy apex. Supplex on the outside, because I breath on this and it can get wet. And I drool on it. The supplex is a better fabric for that.

Another thing is I have two triangular pieces of nylon at the top, to cover the head end. That covers my pillow until I go to bed, in case there’s dew, and to keep out any leaves or needles falling from trees. When I sleep, I have these pieces pulled next to me, covering an area above that I can put glasses, headlamp, watch, extra insulation,… and they’re covered and protected from dew.

Here it is laid out ready to get into:

quilt1

Here it is with the top covered to protect it from dew or leaves:

quilt2

Close up of top, ready to get into

quilt3

Here’s the top closed up like I’m sleeping. My neck would fit between the two triangle pieces. You can see how that will prevent any drafts

quilt4

22 ounces – total weight
10 – down
4.9 – quilt fabric
1.8 – bathtub floor
0.2 – top flap
2.2 – neck flap
2.9 – zippers, Velcro, guylines, elastic, bag

Compare to a Revelation quilt (because that came up first in google search). I think I’m half way between Revelation 30 (2″ target loft) and Revelation 40 (1.5″ target loft). Averaging those two – 11.2 ounces of down, 17.5 ounces total weight.

A medium MLD bivy is about the same size as mine – 7 ounces.

So, I’ve saved 2.5 ounces compared to that combination of quilt and bivy.

My hybrid quilt is 48″ wide, rather than the 54″ Revelation. Because I don’t need to tuck extra width under my sides to prevent drafts. This saves about 1.5 ounces.

And, with a separate bivy, there’s an extra layer of fabric on top. In addition to the layer of fabric on top of the quilt. With the hybrid quilt/bivy, one layer of fabric is both containing the down, and protecting from outside wind, dew, etc. The top layer is about 3 yard2, if the fabric is 0.7 osy then that would be an extra 2 ounces.

I could have saved 0.8 ounces if I didn’t have a layer of fabric on top of the prolite.

 

[Chris K]

Impressive break from the status quo. I like what is happening around the top opening (fabric flaps and bivy “hood”) and the approach to solving the bivy problem generally.

Do the two supplex pieces connect in any way?

[Jerry Adams]

The triangles of supplex/apex/nylon are sewn together at the bottom so it exactly spans the 20 inch width.

Maybe a little air could leak underneath them.

 

[Terran Terran]

I hadn’t realized that you had a zipper on it. Somewhat comparable to the ZenBivy with fewer downfalls. There’s an extra step in setting up the ZB . I can get away without using an extra wide quilt, if I fasten up the sides. I find it a hassle and rarely do. Leaving them fastened, it’s hard to slide into, especially inside a tent. The zipper is an improvement in that regards. I like the hood. If I use a pillow, there’s less room and it doesn’t cover my face as well. I use the pillow under the mat with a FF down pillow under my head. Nice design. Nice work.

[Jerry Adams]

There’s some velcro on the back of the pillow, and a matching piece of velcro on the sleeve piece so the pillow doesn’t blow away

[Dustin V]

@Jerry Adams Do you ever suspend the hood or tie it more vertically as a wind-block?  This looks like a really tight and efficient system you’ve built.

[Jerry Adams]

No, I leave hood flat on my quilt.

Bivies often have a hood like construct that goes over your head to protect you from rain.  I’ve fooled with that some and never liked it.  If it’s raining, you need a WPB fabric, but that’s heavy and not very breathable.  I just prefer a tent in that case.

If it’s not raining, I want unobstructed view of the sky.

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