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Double Quilt - my first down quilt
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Amy Lauterbach
(drongobird) - MLife

Locale: San Francisco Bay Area
Double Quilt - my first down quilt on 09/03/2012 22:34:33 MDT Print View

On August 21 I finished building a two person quilt, and on Aug 22-31 we took it on its maiden voyage - ten days in SEKI NP. Others have done such a great job of describing/showing construction details that I won't repeat that information. But I'll give a rundown of my quilt, and show some details that are a bit unique.

I made my first double-top-bag in the mid-80's by taking a commercial rectangular bag, cutting out the zipper, and sewing a nylon bottom to it. I replaced that bag in the mid-90's with a similar design. About 10 years ago, I bought a custom Nunatak Backcountry Blanket and added a nylon bottom from the hips to the feet and velcro attachments to the pad couplers. I also added a pleated neck collar (more on this later). The Nunatak bag is old and worn and not too lofty anymore, so it was time to replace it. Since we've been using a double quilt for almost 30 years, I had a pretty good sense for the dimensions and features that work for us.

Description of my Love Bird Quilt:

M50 fabric, nanoseeum baffles, and down were all purchased from Thru-Hiker

35.5 oz finished weight. 25-26 oz down.

2.25" tall baffles, for a projected loft of 2.75", which I figure should "rate" at about 25 degrees. 5" chamber width. [edited 10/10/2012: lowest temp on recent trip was 26 degrees, no wind, very humid, double walled-tent REI Quarter Dome tent with mesh doors closed but both fly doors wide open, base layer of clothing and hats -- we were warm enough. Much colder though and we would probably have put on a second layer of clothing or closed the fly doors. On nights when temp was >40 we were very warm and sticking arms and/or legs out from under quilt.]

Main body is 68 inches wide by 70 inches long, not tapered. At the foot end, I added a "vertical" box, 7" tall by 33" wide, which is sewn to the main body without sewn-through seams and effectively forms a foot box. The interior vertical wall of the footbox is 7" tall and the exterior wall is 10" tall -- that prevents the feet from pushing the inner wall to hit the outer wall. And at the head end I added 10" (2 chambers) that have pleats -- more on that later, as it solves a problem unique to double quilts and is, as far as I know, a solution not previously documented on BPL. We are about 68 and 69" tall.

I didn't taper because we sleep better, and we like each other more in the morning, when we have enough room to bend our knees, kick around, and spread out.

I used all black, instead of a contrasting color, so that the 5 yards of fabric that comes in a Thru-Hiker kit was continuous, giving me far more efficiency in making use of the yardage. Not an issue for a single quilt, but important for a double quilt - more on that later.

I used the shop-vac method of moving down. What a great tip that was, easy and mess-free.

I used four different colors of thread (none black), so that the top and bottom of each seam is in two different colors, and seams that overlap or intersect are of different colors. Purpose: I could monitor my tension easily, and I could rip out seams more easily in case I made mistakes. Effect: Looks like a pre-school group with a box of crayons had a party, not very professional, but it got the job done.

I used more down than most people use. Assuming an overall height of 2.75", I filled with 2.0 oz per yard-inch of "900-fill" down (i.e. one square yard at 1" tall). To state it in a different way: To nominally fill a square yard of quilt that has 2.25" baffles using 900 fill down, you would need 3.24 oz of down (2.25*36*36/900). First, I assumed that my volume would be BaffleHeight+0.5", so I wanted to fill to 2.75". That would have required 3.96 oz of 900 fill down to nominally fill each square yard. But I used 5.5 oz per squre yard instead, as per Nisley's statements that down that is more compressed (to a factor of ~2.5) will perform as well as fully lofted down, and my own experience that humid or "old" down will start to shift.

By my calculations (please correct me if I mis-calculated), Nunatak Backcountry Blanket is filled with 1.2 oz per yard-inch ("800 and higher") ; Jacks-R-Better with ~1.6 oz (800+ fill power) or ~1.8 oz if you order overstuff; Enlightened Equipment to ~1.5 oz per yard-inch ("850fill"); ZPacks to ~1.5 oz per yard-inch ("900fill"). My thinking was heavily influenced by Richard Nisely's discussions of down and my own frustration at having down shift when it is humid or old, and wanting to prevent that shifting. Also, my chambers are 70" long with lots of opportunity for shifting, unlike in a single bag. I wasn't so confident in breaking from all trends that I ventured to have shorter baffles for an effective density of 3 oz per yard-inch, but I seriously considered it. I couldn't find a straight-forward thread about this from Richard, but the info is nested into comments such as this one:
http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/12505/index.html?skip_to_post=94791#94791


Double-quilt design issue #1: The fabric is 58" wide, and the bag is 68" wide. So you can't just cut a top piece and a bottom piece and be done. I didn't want a seam running head to foot (visually gawky, and the inevitable puckering/tension that a seam adds changes the length of the fabric in the direction of the seam (unless tension is so loose as to be too loose)). So the main body of the bag (finished size = 68x70 inches) is constructed out of two pieces at 72" x 58", and one piece at 72" x something-less-than-58-but-I-don't-remember-what.
lbq-body-fabric-2


Double-quilt design issue #2: The gap between the two heads is prone to open up and let air flow in. Nunatak solves this with a little flap that hangs between the two people (not too effective in my experience). I made the two baffle chambers closest to the head of an entirely separate piece of fabric 16" wider and added four two-inch pleats when I attached it to the main body (see red arrows in the images below). This way, when the bag is nestled around my neck, it doesn't pull it tight between Jim and me. It's pretty nifty, very effective, and I'm pretty proud of how it turned out.

The little white blot and yellow line in the first photo is a loop of gros-grain. This lets me attach a thin shock cord which can be hooked to a spare shirt (or to a sock with a weight inside it) in order to anchor the center, so that as we thrash in the night we don't displace the quilt, which would let in a draft of cold air. The gros-grain runs through the bag and emerges on both sides, so when you pull on one loop it pulls both top and bottom fabrics in unison instead of pulling them apart. Since there are loops on both interior and exterior I have flexibility with how I attach the anchor. The system worked out very well.

lbq-neck-area-3
lbq-amy-in-bag-2

lbq-neck-area-4
Details of the neck anchor. It's a 14 inch loop of thin shock cord, with two mini cord locks. I used two cord locks so I can pinch my weight between the two and slide the whole unit closer or farther from the bag.

lbq-neck-area-5
The neck anchor is a wadded up red shirt held in place by the two cord locks, and it's extended away from the quilt. I could easily slide the pair of cord locks closer to the bag to better secure the area against drafts.


Here's a link to an entirely different design to address this same problem. I'm not sure how his design would be implemented for baffled down, but it's more food for thought.

The image below shows the underside of bag. The piece outlined is just a single layer of M50. It forms the floor of the footbox. The end of this toward the knees has a thin shock cord sewn into a sleeve, and a mini cordlock that allows me to adjust the width. When it's cold I can draw it closed, but when it's warm I can let it out giving us a very wide comfortable foot box. The fabric does not reach our knees, and it's easy to pull a leg out if it gets too warm. I used shock cord instead of regular cord so there's never excessive tension on the fabric.
lbq-underside

I posted photos and a description of how the quilt attaches to the pads in a separate thread: Pad and Quilt Coupler

Impressions, and open questions:

We didn't have any really cold nights on our trip. One night with light frost, and a second night with heavy frost and ice skim in the platy bottles that were under the fly of the tent. We slept in a traditional double-wall tent with the netting closed but the doors of the rainfly wide open, wearing thin base layer, hats, and socks. On the colder of those nights, by morning, I was feeling a tiny bit of a chill - not enough to put on a second layer since it was about time to get up, but if it had been earlier in the night I would have taken the time to add a windshirt. Jim was plenty warm enough even on our coldest night.

I like the idea of the water-repellency of the M50 and believe it will keep the down drier. On the other hand I don't think it will dry out as fast when left in the sun. When I make my next bag (a warm weather version using the same design) I may use nobull or pertex for part of the liner, just so it has more air passing through. I'm undecided about this. Also, with a fully M50 bag, it does loft a bit slower than a bag where air moves through the fabric more freely, but it's fast enough that it wasn't an issue for us. I can imagine it being a "sales" issue if a user in a store was assessing an M50 bag and was not impressed by how it looked 5 minutes after removing it from a stuff sack.

We really liked the dimensions. Our last quilt was ~64" wide instead of 68", and the extra few inches made for a better wrap-under at the edges. We were able to still have fabric effectively wrapping under our sides even when we were both on our sides and facing opposite directions - the most "stressful" position in terms of width. The roomy foot-box was like heaven - we could bend our knees and spread our legs and feet with luxury. I think 68" wide is our sweet spot!

I thoroughly enjoyed making the bag, but spent DOZENS of hours thinking about the design/construction details. I won't have to redo all those hours for the next quilt, because I'm happy with my decisions. I didn't count the hours it took to construct. [edited Oct 22: I have completed my second quilt with identical design and it took FORTY-SEVEN hours to build!] Anybody who thinks they are getting a bargain by making their own baffled down bag instead of buying from Katabatic or Nunatak or Enlightened or Jacks or ZPacks -- that's only true if you are retired/unemployed and don't assign much $ value to your time! A sewn-through bag would be a lot faster and might be a bargain, but a baffled bag with a real footbox is quite time consuming. Fortunately for me, I'm retired.

I took my sewing machine to the shop for a much needed overhaul before I started. That was a critical step, boy did things work more smoothly after a cleaning and tuning.

Edited by drongobird on 02/04/2013 11:00:29 MST.

Colin Krusor
(ckrusor) - M

Locale: Northwest US
Double Quilt on 09/04/2012 08:54:52 MDT Print View

Excellent design and craftsmanship. The quilt looks fantastic, and the fill weight/total weight ratio is impressive. I made a down double quilt with a 0.33 oz cuben shell last year, but my girlfriend is not fond of the vapor barrier effect, so I plan to make one like yours (although mine won't match the quality of yours).


"And at the head end I added 10" (2 chambers) that have pleats -- more on that later, as it solves a problem unique to double quilts and is, as far as I know, a solution not previously documented on BPL."

I used a similar solution (not pleats but a flap) in a summer quilt:

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=66925


I'm looking forward to hearing about field testing of your new quilt. It seems very well designed and it looks great.

Edited by ckrusor on 09/04/2012 09:03:23 MDT.

Amy Lauterbach
(drongobird) - MLife

Locale: San Francisco Bay Area
Double Quilt on 09/04/2012 09:26:44 MDT Print View

Colin - thanks for the link to your quilt description. Very cool design you came up with. I added a link to your page in my original report in an attempt to make sure other people designing double quilts will see your solution too.

David Chenault
(DaveC) - BPL Staff - F

Locale: Crown of the Continent
re: Double quilt on 09/04/2012 12:18:45 MDT Print View

Fantastic project and great summary of the design and construction. Seems like it will address many of the issues with double bags very well.

It wasn't quite clear how you attached the additional neck/head section without any sewn through seams. ??

Amy Lauterbach
(drongobird) - MLife

Locale: San Francisco Bay Area
Double Quilt, pleated end on 09/04/2012 13:37:24 MDT Print View

I was afraid somebody would ask about the steps to construct the pleats in the neck area :) It's not very difficult to implement, but I'll have a bit of a tough time describing it. Here goes, referring to the image below.

The main body (70x70") has baffles that run across the width. Instead of finishing the head end by sewing the top panel (shown in red below) to the bottom panel (shown in orange below), there is a baffle connecting them.

Then there's a new piece of fabric (86x22 plus seam allowances), shown in blue below. I put one baffle into that, folding it back over on itself (so there's actually no seam at the head end of the bag). I then basted pleats in so that the 86" width is reduced to 70". Then I sewed the top 70" edge (once 86 but reduced to 70) of the fabric shown in blue below to the 70" edge of the red fabric shown below, and sewed the other blue 70" (formerly 86") edge to the fabric shown in orange.

Actually, the baffle material, red edge, and top blue edge, are sewn together with a single seam, such that the red and blue edges are then enclosed inside the bag. But to connect the orange edge and the blue edge, I had to finish the edges of each piece and stitch them so the final finished edges stick out. This is an aesthetic detail that is not important to function, and the steps to do this should be easy to work out for somebody with a bit of sewing history.

And the final detail of this section: prior to stitching the two 70" edges, I put in a loop of 1/2" gros-grain ribbon, centered 35" from each edge, that passes through the bag and emerges on either side. This lets me anchor the bag to the pad in a way that pulls the top and bottom panels in parallel.


lbq-attachingNeck




lbq-blue-fabric-open-flat



lbq-pleat-spacing


Edited Oct 22: Here is the spacing diagram on my second quilt. lbq-secondquilt-neck-spacing


Edited Feb 3 2013: Here is the spacing diagram on my THIRD Love Bird Quilt, maybe this spacing will be perfect.

LBQ3 Pleat Spacing v2

Edited by drongobird on 02/04/2013 10:57:04 MST.

David Chenault
(DaveC) - BPL Staff - F

Locale: Crown of the Continent
re: neck pleats on 09/04/2012 14:26:48 MDT Print View

Thanks Amy, looks like a genius solution.

Amy Lauterbach
(drongobird) - MLife

Locale: San Francisco Bay Area
Double Down Quilt on 09/04/2012 14:31:37 MDT Print View

AlanD sent me a note and suggested that instead of attaching the center of the neck area (where I've put the little white gros-grain loops) to the pad, I could attach it to a sock with a weight in it. That would serve to hold it down, but wouldn't strain the fabric when pulled, and would let the two people move their arms back and forth. Brilliant. It doesn't require a change to the way the bag is constructed, just improves the way those little gros-grain loops are used. I updated the original post.

Amy Lauterbach
(drongobird) - MLife

Locale: San Francisco Bay Area
report from using my new double quilt. on 10/10/2012 15:28:53 MDT Print View

I added the following info to the original post

lowest temp on recent trip was 26 degrees, no wind, very humid, double walled REI Quarter Dome tent with mesh doors closed but both fly doors wide open, base layer of clothing and hats -- we were warm enough. Much colder though and we would probably have put on a second layer of clothing or closed the fly doors. On nights when temp was >40 we were very warm and sticking arms and/or legs out from under quilt.

Edited by drongobird on 10/10/2012 20:05:20 MDT.

Nick G
(HermesUL) - F
"Maiden voyage" on 10/10/2012 18:09:36 MDT Print View

Sorry, I just couldn't resist commenting on the usage of the term 'maiden voyage' for a lovebird quilt. Too good to resist.

Also, looks like a fabulous and well thought out design. Also looks like a fabulous weight savings. I'm almost as jealous of your skills as I am of the fact that you have a partner who'll come with you.

Amy Lauterbach
(drongobird) - MLife

Locale: San Francisco Bay Area
Double Quilt - my SECOND down quilt on 10/22/2012 16:32:41 MDT Print View

I finished a second Love Bird Quilt. The design is identical to the first but this one has 1.5" baffles and 19 oz of down (the first had 2.25" baffles and 25 oz down). This time I kept track of my time, and I spent forty-seven hours! It's good to be retired. I have promised to make one for my brother and for a friend, and I'll keep track of time - hopefully I can get it down to 35 hours per quilt.

This time I had enough confidence to use all black thread, and it looks much nicer :) The weight of the shell in both quilts is very nearly 10 oz (the change in baffle height has minimal effect on weight).

I updated my original post with pictures of the "neck anchor". After experimenting on our last trip, I'm now happy with it and I don't feel any need to refine it.

Edited by drongobird on 02/04/2013 10:58:21 MST.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Double Quilt - my first down quilt on 10/22/2012 22:14:49 MDT Print View

Hi Amy

I'm impresseed. The neck bulge is really cute. The centre weight string is intriguing. I made the footbox on ours come up a little further.


I note that many people have the idea that you can calculate how much down to use from the fill-rating. This leads to the idea of 'over-fill'. Frankly, I think this is a totally silly missapplication of the fill-power rating.
'Fill-power' measures the quality of the down.
Temperature rating determines how much down to use.
They are NOT the same thing at all!


Cheers

Amy Lauterbach
(drongobird) - MLife

Locale: San Francisco Bay Area
Re: Double Quilt - my first down quilt on 10/22/2012 22:41:02 MDT Print View

Roger wrote "I made the footbox on ours come up a little further."

On our prior quilt, the single layer of fabric under our feet extended all the way to our hips, where the quilt was attached to the pads via velcro. On this one, I made two changes. 1) I added the shock cord in the hem of the fabric (under our calves/knees) that pulls it together without restricting movement and 2) I now attach the quilt to the pads at mid-thigh instead of at hip, so when it's cold I can cinch it "closed" down there. Between those two changes, it seems like it's going to work to have the short piece of fabric under our feet.

To be honest, I initially made it that short because I had a scrap of fabric that width, and I'm trying hard to use my yardage efficiently. I basted it on, figuring that I'd probably need to replace it. Turns out to work just fine as is. And since the quilt was so warm, I found it nice to be able to easily take my feet out of the pocket and vent them out the side on warm nights.

Experiment, tweak, adjust, try again. This time around, the width was randomly determined by the size of my scrap :)

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Double Quilt - my first down quilt on 10/23/2012 03:15:10 MDT Print View

Hi Amy

> I initially made it that short because I had a scrap of fabric that width,
Love it.
And of course, the size of the bit of green uncoated fabric I had available had nothing to do with just how long I made my footbox ...

What I sometimes do is to put the end of the two (full-length winter) mats inside the footbox. That really keeps the over-quilt under control, while we snuggle up in our light-weight summer quilts under the winter over-quilt.

Cheers

Daryl and Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Re: Double Quilt - my first down quilt on 10/25/2012 08:35:33 MDT Print View

I'm blown away by your skills and patience on these projects.

Amy Lauterbach
(drongobird) - MLife

Locale: San Francisco Bay Area
Love Bird Quilt #4, with variable baffle height on 07/12/2013 17:33:44 MDT Print View

Today I finished making my fourth Love Bird Quilt, this one for my friends M&M. I didn't keep close track of time, but I believe it's in the same range as quilt #3 - about 47 hours. If I figure out a better construction technique for the footbox I might save 4 hours, but I don't see any other steps that can be optimized.

I made the first two quilts for Jim and me, first a cold weather quilt, then a warm weather quilt. A&A slept in the cold weather quilt for a week, it fit them just right, and they liked it. So I made the third quilt for them.

Then I loaned our quilt to M&M who slept in it for a couple nights. It fit them just right (except length) and they liked it, so they wanted an exact copy, but 3" longer.

For this one I tried something new. Manfred sleeps warm, and Michelle sleeps cold, so she wants more down. I made the baffle height on her side 2.5" and on his side 2.0". I don't know how much difference it will actually make, but our hope is that the down will naturally skew toward her side and give her a bit more warmth.

M&M borrowed my brother's Nunatak Dual Arc Alpinist, and they found the foot box too small to be usable. Same assessment from 4 of the 5 couples who've tried it. I think that Nunatak design is a dud, sad to say. Jim and myself, A&A, and M&M have all found the foot box on the Love Bird Quilt to be perfect -- interior dimensions 35" wide and 7" tall, and rectangular, so when laying on your back your toes can fit right up into the corners. When sleeping on your belly or your back your feet are at a diagonal, pointing toward corners, neither vertical or horizontal. A round or oval foot box is optimized for horizontal or vertical feet; feet are never vertical, and are horizontal only for side sleepers.

27.3 oz 900-fill down + 10.7 oz shell = 38.0 oz final weight
Loft on one side is 2.5" and on the other side is 3.0" (assuming baffle height + 0.5")
Down density is 2 oz per "yard inch" (36x36x1"). That's more down than most people use.

I think my next project will be a single quilt, that Jim and I can each use when we take solo hikes. We have a WM bag and a Nunatak Arc Alpinist. But now that I'm used to a spacious comfy bag those two feel way too confined in the foot box, so I might make a single quilt with a 23" wide x 7" tall foot box.

Tanner M
(Tan68)
lines and squiggles on 07/13/2013 08:50:50 MDT Print View

I thought you did a really good job with the descriptions and diagrams.

peter vacco
(fluff@inreach.com) - M

Locale: no. california
Re: Double Quilt - my first down quilt on 07/13/2013 09:38:28 MDT Print View

" spent DOZENS of hours thinking "

something along those lines could keep a Man busy for what .. most of a lifetime !

---
perhaps :
fear not the loss in material from not taking into account the supplied dimensions. once you toss that to the winds, it can free up the design process. ask perhaps, what would i do "in a perfect world", as opposed to "what can i do with what i've got", and very often you come to a nicer result with little loss in efficiency. the leftover material makes into stuff bags and such, as these things can be given away (always fun! ).

is a beautiful project !
----
the only flaw i see is the Most Glaring and Obvious oversight of .. when you made the little circles designating the head locations in the first picture, that i , being the sexist pig that i solidly am, would His blue, and Hers pink(ish).
it is granted, a small thing , but This is BPL !

cheers,
v.