Mathineer's First Down Underquilt

[mathineer]

I use S-biners to secure my underquilt suspension to my hammock continuous loop with no problems. And I find that the shock cord running through the channels is what causes the uplift and pulls the quilt up against your back, I don't think you'd get the same effect hanging it off the shock cord ran through the end channels. But you can always give it a try and add the shock cord through the long Channel if necessary.

Thanks for the input. Rather than putting more time trying this and that after all of the time put into the down issue, I thought I'd just ask for opinions. What you said makes sense. I think I'll just add both and be done with it. I'll finish it up, and on to the next project - bug net. Then the down top quilt to match the UQ.

mathineer

[mathineer]

Finally added the shock cord and weighed in the stuff sack (with the quilt hangers moved over from another quilt): 24.9 oz

IMG_0905.jpg

mathineer

[Cruiser51]

I may have missed it, but i didn't see over stuff mentioned anywhere. Most of the cottage vendors state an over stuff of ~30%, I use about 40% and have found that seems to work well.

I don't think that the 40% of over stuff to get it to work right is entirely due to down issues, as much as I enjoyed the math .... I believe our calculators are still flawed, in that they snap a static picture of what is a dynamic system. They provide a good estimation, but as those chambers fill the shape is going to start changing towards circular and that will increase the available volume significantly, using a 30-40% overfill seems to mostly address the issues with the estimations and possibly down parameters.

What over stuff did you use? On my 2.5" UQ I used 40% and it is filled about right, not like a ballon, but filled with some slack ... that was with 850 FP and a reputable dealer.


Brian

[mathineer]

I may have missed it, but i didn't see over stuff mentioned anywhere. Most of the cottage vendors state an over stuff of ~30%, I use about 40% and have found that seems to work well.

I don't think that the 40% of over stuff to get it to work right is entirely due to down issues, as much as I enjoyed the math .... I believe our calculators are still flawed, in that they snap a static picture of what is a dynamic system. They provide a good estimation, but as those chambers fill the shape is going to start changing towards circular and that will increase the available volume significantly, using a 30-40% overfill seems to mostly address the issues with the estimations and possibly down parameters.

What over stuff did you use? On my 2.5" UQ I used 40% and it is filled about right, not like a ballon, but filled with some slack ... that was with 850 FP and a reputable dealer.


Brian

After I cleaned out the Rose Feather down and re-stuffed with Wilderness Logics goose/duck mix (rated at 850/800) I stuffed about 1.5 oz per chamber. The Gadget calculator called out about 1.4 oz, if memory serves. So that's just 7% overstuff.

As for the calculator, I would love to know how those equations were derived. Also, I think the Gadget version calculates longer outer shell than the CatSplat. That makes the filled out cross section area greater.

mathineer

[Cruiser51]

Catsplat made a great tool and Gadget gave it more detailed modeling (IMO) and the result is a workbook allowing the user great convenience as far as what to cut and stuff, creating a very useful tool for the DIYer (I use the same WB).... but in the end, I am convinced that it only puts you in the right ballpark and over stuff is required to a) meet user expectations b) meet the reality that the cross sectional area in a TQ or UQ is a bit of a moving target under use.

If you follow CSs thread, his and Gadgets model are explained in fair detail, enough for my eyes to start glazing over .... I think that somewhere on the HG website it says they use about 30% OS ... I use 30% for UQs, but 40% for differential UQs (they seem to need more to loft enough to my eye).

If the cottage vendors are using over stuff of the most expensive component ... I am going to pay attention to that, so far it has worked out well for me.


Brian

[Carrico]

Personally I don't use any of the calculators. I just do a volume calculation, length × width × thickness / fill power. Divide the amount of down I put in evenly amongst the Chambers. Has always worked out good, I've also had no issues with rosefeather down with the three quilts that I've made. If you have any of that Wilderness logic down left over I would love to see some comparison pictures, many people have said that they would post some but I have yet to see any. Trying to save some time ha ha ( starting week 9 of my 6 week wait) I ordered a 20 econ incubator so that I can outfit one of my girls with my DIY quilts, interested to see the difference if it ever shows up. Hammock gear comes with a standard of 15 to 20% over stuff