I have made 3 quilts and can now spit one out in under 8 hours. I also found a few short-cuts to make it easier and lighter.
For Baffles, I make them only in the middle 40” , (36” for me). The cut size of baffles would be 42“ long so it can be sewn 1“ past the 40“ lines on each side, (in order to close off the vertical lines.
For a 3” loft quilt, I would use 2” baffles. This means that the cut size of each baffle would be 2 1/2", for an extra 1/4” to sew to each side.
For you dimintions I would go 84” in length with a draw closure at the feet, (needs to be about 6-8” longer for the closure).
For the width go 64”, only 40” of that would be baffled. For the remaining 12” on each side, use two 6” sewn-thru vertical compartments with only ½ of the down loft in them. The compartments taper and will be tucked under you so the extra loft is not needed.
When sewing the quilt, sew up one side, the bottom, (adding the draw closure), and the 2 vertical lines on the same side you sewed the side up, (for the two side vertical compartments). Remember, the inside vertical line should have 1” of the baffles sticking out so it seals the baffled compartments.
Now fill the 2 vertical compartments. Then sew the top closed, (sealing the 2 vertical compartments). Make sure you do not sew the last 12” on the top so you can fill the 2 vertical compartments on the other side later.
Next fill the baffled compartments, (with 6” spacing you would have 14 compartments). Use a cardboard piece from wrapping paper to stuff the down into the compartments in order to keep the down at the bottom.
Then sew the 2 vertical lines and the side that hasn’t been sewn.
Now all you have to do is fill the last 2 vertical compartments and sew the rest of the top. Then sew the bottom part together and you are done.
You could have also added a closure to the top of the bag.
The bottom of the bag would be 40” as far up as you wanted to sew it together.
I would recommend 42”.
Now comes the weight of the bag.
40” width times the length 84” = 3360ci
64”- 40” (already calculated divided by 2 for each side) times 24” (to were it starts to taper) -
24” X 12” X 2 (for each side) = 576ci
Tapered area is ½ of 22” X 12” X 2 = 264ci
Total = 4200ci
If using 800 fill and 3” loft in the center and 1 ½” on the sides you will need:
3360ci needs 4.2 ounces for each inch
(X 3 = 12.6 ounces).
Divide by 14 and covert to grams for each compartment.
576 + 264 = 840ci needs 1.05 ounces per inch
(X 1.5 = 1.575)
Total of 14.1 ounces of down.
Fabric - the momenteun90 from thru-hiker is awesome. At 1.05 ounces per sq yard it is also very light.
The fabric pieces would be 4200ci each. The 13 baffles would add 1365ci.
4200 X 2 + 1365 = 9765 Divided by 1296 = 7.54sq yards X 1.05 (fabric weight) = 7.9 ounces of fabric.
7.9 + 14.1 = 22 ounce for the quilt weight. Add about 0.2 ounces for each draw closure and 0.1 for the thread and you have a 22.5 ounce quilt with 3” of loft you can take down to 20* with your clothing.
Not bad at all.
Hope this helps.