Over Stuffing vs Temp Rating

[Just Bill]

Bill, Interesting point about an UQ being different than a TQ in it's "rigidity", Not something I had considered but that is very true and it was an UQ that I had good luck doing that with. Your point about the TQ behaving different when taking overstuff is noted, but I don't recall ever noticing any perceptible "extra bulge" in the fabric or loss of width from adding overfill, I'll be sure to measure the finished width next time we do an overfilled one to see how much this is actually occurring on a 2 or 3oz overfill.

Another thought... a topquilt doesn't act exactly like a rigid wall either, I mean it's not flat when in use, even though most are cut without a differential, it still bends around your body, and since the inner shell isn't really getting pulled tight around something (like an UQ would be) then it's inherent looseness means that the baffle isn't necesaairly going to take the rectangle or bulged rectangle shape from your pdf because there is a differential of sorts going on with the way it curves around you. In places where the inner shell is loose the inner shell fabric may bulge inward while the outer shell of the same baffle may remain fairly tight/flat. Not sure how the interior volume of the baffle changes when one side is loose and the other tight but that certainly happens some on the inside of a topquilt.

As to the first point... you'd see the overfill deformation more dramatically in a 7d/.67 ounce shell. I first noticed this when I did a practice quilt in cheaper 1.1 before using thru-hiker's M50... the lighter the shell, the easier it is to deform. I don't know exactly what you use for your shell material but just something to keep in mind. Might not seem like much but technically a 1.1 is nearly double the material of SUL shell and the down has to overcome the weight/gravity/rigidity of the material itself as well.

Other than your neighbor (Katabatic) you are correct... not many building a shaped top quilt.
On the other hand, unless you are building a section of a sleeping bag like Katabatic... there isn't much need.
Other than a true side sleeper on the ground there isn't really that much curve. Even less so in a hammock hanger than a ground dweller.

Top quilt baffles.pdf

Here's a few common curves in the same top quilt. Standard 2"x5" baffle. This is not allowing the extra bulge from the perimeter shrinking (loss in width from last PDF).

It does however show how the baffle would change shape when bent under a radius.

On the right- would be if only one side (inner) would bulge due to the radius. Although that's not that realistic- you'd have to stretch the outer shell into a polygon shape to pull one side dead flat.

On the left (blue fill)-
More realistic- the outer shell would curve (but remain 5" long) and the inner shell would bulge into the mirror image of that curve.
This would once more create the familiar shape from the last PDF... but without the reduction in overall width.

So yes- flat on the table and relaxed. The quilt would lose a bit of width. But once curved you're basically still creating the same shape within the relatively large radius curves we use.
To an extent... that's why the vertical baffle design works so well in top quilts.

If doing a section of a sleeping bag as Katabatic does... then you need to worry more about it so you don't crush out the baffle under a tighter radius.
As much as I admire the work they do... for the most part it's over engineering the end product. If you ground sleep on your side... probably the best quilt you can buy.
But for the average sleeper, especially in a hammock... it's serious overkill.

[Countrybois]

[QUOTE=warbonnetguy;1920544]

"I feel like there is a fair amount of leeway in regard to baffle height and I can pretty much guarantee if you got all manufactuers to tell you their 20deg baffle height they won't all be the same... even though they may all be accurately rated at 20 deg. However, manufactuers making very similar sized products (50" wide x 72" long topquilts with a taper for instance) will often have strikingly similar fill amounts for any given rating, and this is no coincidence, fill amount is the major factor effecting temp rating, not baffle height which can and does vary from shop to shop. Also companies making a quilt in 5 or 6 different temp ratings are not all using 5 or 6 different baffle heights...Some may so but some do not...some use the same baffle height for 2 different ratings and just adjust the fill weight, and nobody to my knowledge lists the actual baffle wall height anymore because most customers give it way to much importance while in reality the exact baffle height for a given temp rating is probably one of the least important factors and shouldn't even be considered by anyone other than the designer.."






I would agree with Brandon.... Here are photos of two manufacturer's 20° top quilts. UGQ (gray) and Loco Libre(blue) . It appears as though one is understuffed and/or the other overstuffed. In reality, the loft is almost identical but the shorter baffle height on the UGQ makes it appear that it has more fill.

I don't have a Warbonnet quilt, but I do have an HG Burrow coming soon and can post an updated comparison when it arrives.

(I have had the UGQ to 18° comfortably with a medium base layer and an overstuffed 20° underquilt, so no issues with its rating)

My observations..... You may get less down shift with the 'fuller' chambers, but you also are more likely to experience some bridging.

First world problems.....

Sent from my SAMSUNG-SM-G891A using Tapatalk

[Just Bill]

First world problems indeed, lol.

People expect that 'downy goodness' and 'bursting at the seams' look of a 'properly filled' down product. Nobody wants the quilt to look 'underfilled'... even if in truth it is properly filled.
So vendors give the customers what they want to see. Very few (if any) folks would pull the quilt out and check to see if it came in an inch under the target width or length if it was nice and properly poofy looking.

Maybe I'm putting words in his mouth but; really baffle height isn't as important as fill weight and/or average loft. I think that was a portion of Brandon's point. Certainly the portion of it I agree with.
Doesn't really matter how you get there so long as you don't go too far out of bounds. As he mentioned... most folks more or less use the exact same dimensions... and with those dimensions it's not too hard to sort out how much down the quilt should have if you'd care to.

If it's a more casual comparison not involving a calculator... providing you're looking apples to apples in terms of size and temp rating... comparing fill weight is easy enough and likely tells you all you need to know.

There is no manual of down goods standards to consult. If there were there wouldn't be much to discuss
Everyone does it their own way. Some are nerds with numbers (or carpenters with Autocad) some just keep adding a pinch until they call it good enough.
For the most part if a vendor is around long enough to buy from... whatever they are doing probably works.

[HandyRandy]

So what you’re saying is… “It’s simple and complicated at the same **** time.”

It’s been a fun read. And exactly what I would have imagined if I put JustBill, BillyBob, and Brandon in a room and just asked a them a “simple” quilt question, lol. Love your passion and scientific perspective, guys!

I have an idea for a new type of insulation that is both natural AND man-made at the same time! It’s called… BEARD HAIR! Just need to figure a way to humanely harvest enough beard hair to fill a winter quilt set…