After seeing a number of people trying to avoid the hassle of baffles I thought, "there has to be an easier way..."
People avoid using baffles in construction because of the perceived difficulty in sewing baffles. For down, this limits you to sewn through designs, which because the seams have no insulation, are not generally considered suitable for 3 season & winter weight quilts.
My first thought was three layers with the middle layer forming triangles bouncing between inner & outer layer the whole length, like an old truss bridge.
Then I thought, how would I seal the sides on that?
1. We could give the shell material extra width
2. run a stitch along the outer edge
3. then another stitch ~1.5" in,
4. then roll the hem into something not too nasty looking. A hack, but the goal is easy, not pretty.
I thought the Triangle baffles would still be tricky trying to sew though since you'd have to alternate sewing middle & top together then middle & bottom together... and I'm looking for simple
Offset String of Pearls (OSoP)
What about Full circles but not linked in the middle (that would be nothing more than a sewn through) but near the "bottom" so that 2/3rd of the circle are above the seam & 1/3rd is below?
(skip the math if you want)
r = radius
p = number of pearls (read circles)
Link pearls at the 120 degree point
Length finished = (p-1)*sqrt(3)*r+2r
See google doc spreadsheet here if you want to play with it
After doing lots of math this one simply requires a lot of pearls. A 73" long TQ with 3" circles running horizontally, that would take 27 circles top to bottom, the time & trouble spent stuffing so many small cells would eat most of the time benefit of simpler construction. 74" length with 4" diameter cells running horizontally requires 21 "pearls".
Here was the surprise for me. Using 4" diameter "pearls" (cells, spaces) 50" continuous width, almost 74" long (73.8"), total calculated weight (not including thread, snaps, elastic) was 31.7 oz with 17.6 oz of 900 fill down, 20% over stuff. This lines up a little worse than HammockGear's 0 deg Burrow TQ which is 27 oz total with 16oz of 900 weight down. Now their number includes thread, elastic, etc so you've probably got another 2-4 oz to account for but theortically (emphasis in original) this is not bad. The one thing where a normal baffled quilt will definitely beat this is your feet. If you feet point up at a seam line - zero insulation on your toes. A length of shell material that bridges over the last 3-5 pearls could fix this or do it to the whole thing... See Box of Chocolates below
If we flip things vertically, the way most UQ's are done, that cuts down the number of baffles & may fix our foot problem as well. It'll look something like a swimming pool floating mattress
74" tall, 49" wide
Total Down 17.4 oz
Calculated Minimum Weight 31.0 oz
So what if you sewed loose baffles, to a flat shell? Like Chocolate Truffles or Chocolate Hills, Bihol, Philippines.
Spaces need to hold the same volume of down in a normal baffles quilt, possibly more to account for their non-uniformity. We can't over stuff it too much or it'll deflect the flat side (this is built into the design of the Offset String of Pearls). Also need to factor in stuffing the space, so we don't want the spaces too small. Let's try half circles.
A normal 20° F baffled quilt should be 2" tall in cross section. For a 6" length that's 12 sq in (2"x 6"). If we take a half circle, radius 3", that's a volume of pi * r^2/2 = 14.1 sq in. Close. It still has the foot issue described above.
For simplicity let's go with complete half circles, radius 3" that means 72" or 78", we'll go with 72"
Spreadsheet here https://docs.google.com/spreadsheet/...l=en_US#gid=26
72" tall, 50" wide
Total Down 11.3 oz
Calculated Minimum Weight 21.6 oz, again, no thread, shock cord, etc
To flip it vertical swap your width for height & pick a good radius. Spreadsheet
Box of Chocolates
So what if we put a lid over a set of half circles, like a box of chocolates? <cue Forrest Gump quotes> Just run a third piece of shell material (yes, UL just went out the window)
For the "lid" cutting length its the 1/4 circumference up + 1/4 down + (number of chambers -1)*diameter + 2x sewing margin.
Same Spreadsheet as above for calculations. Assuming we use a 0.9 oz material for the lid since it doesn't have to be down proof.
72" tall, 50" wide
Total Down 11.3 oz
Calculated Minimum Weight (with lid) 26.3 oz again, no thread, shock cord, etc
- The increase in weight vs traditional baffle construction is not to bad (~15% + thread & shock cord) but probably not good enough for UL enthusiasts.
- Using a vertical orientation reduces the number of cells to sew & stuff and is probably the course that should be taken.
- If the vertical orientation is used & the flat or flatter side is put on the outside the curvature should close the gaps
I think these could represent an easy entry into the fun & exciting world of baffled down quilts. Of course, this is all theoretical , I haven't tested any of these yet, just one big long brain storm. <exhale>