Costco Differential Cut 3/4 UQ with Faux Baffles

[GadgetUK437]

This is how it looked after some shaking down and hanging overnight,


this is pretty chunkily overstuffed (all down one end!),


Crunching some numbers, you will see that as it stands it is understuffed by 17% and is rated at 43°F (6°C),


If I were to raid one of the other Costco Throws and transfer the down to this one, giving it a total of 12oz of down, then it would be overstuffed by 63% and be rated at 17°C (-8°C),

[Boston]

If I were to raid one of the other Costco Throws and transfer the down to this one, giving it a total of 12oz of down, then it would be overstuffed by 63% and be rated at 17°C (-8°C),

That temp calculator isn't very accurate. It was an experiment in trying to predict temp rating based on comparing loft, and amount of down and correlating it to manufacturer's ratings. It's ok when you keep overstuff around normal levels (aka around the same levels as the cottage guys). However, it equally weights the amount of down with loft, which isn't correct. 63% overstuff isn't going to net you a 26*F improvment. Based on my most optimistic estimate you might see a 12*F improvement. But more likely you'll see maybe half that. Loft is king, judge your temp rating based on that. Most likely you have a quilt that will get you into the 30*s.

I don't like the Jardine formula either (even though I'm the one who added it to that calculator - I've realized since it's not the best predictor). It works ok in the 20-40* range, but will over predict for lower temps, because insulation requirements aren't linear. The BPL chart is the best reference I've found, and seems fairly accurate.

https://backpackinglight.com/bpl_sle...ion_statement/

Keep in mind this is average loft, not peak loft.

[GadgetUK437]

I did think there should be some roll-off in the benefit of overstuffing at some point. With that formula it just keeps adding to it.

What would be a sensible max overstuff?
And what sort of over stuff do the vendors do (as standard)?

[Secondmouse]

Crunching some numbers, you will see that as it stands it is understuffed by 17% and is rated at 43°F (6°C),

If I were to raid one of the other Costco Throws and transfer the down to this one, giving it a total of 12oz of down, then it would be overstuffed by 63% and be rated at 17°C (-8°C),

you are talking about your modified throw?

how much understuffed to you think an unmodified throw is?..

I've taken an unmodified throw down to 48*F with just long polypro baselayer in relative comfort. however, because I am too tall for its length, no footbox, pad straps, or cinching closures I had some trouble with drafts at foot or shoulder.

[-c0de-]

Glad to see all of your work on our similar ideas. I see that you worked out some of the things I had not thought of yet (or gotten around to realize that I would need to think about).

I'll be following this thread to see how far down the rabbit hole you end up going, but so far, it looks stellar! I'm just wondering how much more down will be needed for this thing to be decent.

[GadgetUK437]

you are talking about your modified throw?
how much understuffed to you think an unmodified throw is?..

Indeed I was.
Your second question, is.... not really a question.
You see, an unmodified throw is sewn through, constructed in 2d, it will expand to whatever fill you put in it (and get narrower/shorter). Of course, there is a limit, when the 5" squares become spherical, but that would be a bit comical.
On the other hand, a quilt with baffles is a 3d, box construction, which has a fixed volume. Therefore the fill (and overstuff) can be calculated.

[-c0de-]

What would be a sensible max overstuff? And what sort of over stuff do the vendors do (as standard)?

--
Gadget

From my research, 30% seems to be the max that vendors tend to overstuff with.

[Secondmouse]

Indeed I was.
Your second question, is.... not really a question.
You see, an unmodified throw is sewn through, constructed in 2d, it will expand to whatever fill you put in it (and get narrower/shorter). Of course, there is a limit, when the 5" squares become spherical, but that would be a bit comical.
On the other hand, a quilt with baffles is a 3d, box construction, which has a fixed volume. Therefore the fill (and overstuff) can be calculated.

it's not a question??? jeepers, I could have sworn it was when I asked it. I even used the squiggle over the dot thing at the end...

[FJRpilot]

On the other hand, a quilt with baffles is a 3d, box construction, which has a fixed volume. Therefore the fill (and overstuff) can be calculated.

Actually if it was constructed of something rigid, you would have a fixed volume. The fact that material stretches and can be compressed impacts the ultimate goal of creating a quilt, perceived "warmth".

There is a lot of discussion as to why people overstuff in the first place. Most vendors do not as a practice overstuff their quilts. They offer it as a option, catering to their customers opinions that over stuffing will make a warmer quilt. I subscribe to the view that overstuffing a quilt off sets the inevitable reduction in loft you will experience in any quilt over time as you stuff it into and out of storage sacks that in reality breakdown the down fibers that actually contribute to creating pockets of air that your body warms when it being used.

Down is rated base on its ability to fill a giving volume. Overstuffing simply increases the volume it can fill. If you don't increase the volume, then you are compressing the down and in effect lowering the potential warmth of the quilt


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[Koolranch]

Wow you guys are some mad scientists. I slept in my costco underquilt at 50 and was very warm. Im thinking it could do 40s .