Cold weather underquilt

[bikerbobber]

Hi all. Been a while since I was here.
I love this forum but the search function sucks...

I'm looking to make a -20f ish UQ for winter camping in Ontario Canada. Inspired by Shug of course...
I'm having a hard time finding info.
I did find Catsplats table but he specifically says it may not be accurate for extremes.

Here is some background;
I'm 5'8 around 190# at 51 yoa. I'd say I'm a normal sleeper.
I have alot of spring (May in Algonquin park for a week every year and used to do April / May motorcycle rallys) hammock experience.
I've DIY'd several hammocks, tarps and bags. As well as making other equiptment like stoves and a Pulk.

Basic design ideas;.
I want a full length underquilt.
I'm thinking 72 x 45 ( remember, I'm short )
I've already ordered;
8 yards 1.0 HyperD (calendared)
3yrds .67 noseeum mesh
Guterman mara 100
.5 grosgrain.
1/8 shock cord
Cord locks
2# 900 down.

What are the thoughts on baffle direction. Length vs width?

I'm thinking baffle height at 4" filled to 4.25" should do the trick. Approx 2.5 oz per baffle?

Looking for all thoughts and ideas. My stuff arrives in the 15th.
Thanks!

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[Shug]

Make sure to peruse the DIY Stickies on here.
Also search making an underquilt on a search engine. I found a lot on Safari.
https://video.search.yahoo.com/searc...mmock&fr=aaplw
These may give insight:
http://www.tothewoods.net/RedRiverGo...GorgeQuilt.php
https://www.hammockforums.net/forum/...rchid=13187047

You can also search on You Tube as there are many tutorials to get you started.
Shug

[Cruiser51]

I have based all my quilts on the latest CatSplat calculator and they have worked out pretty well. I camp in pretty much the same locations as you and found the numbers for -5C and -20C deem to work out fine (FYI, I use a 30-40% overstuff).

After doing a lot of research into how the Fill Power is determined ( yes, I reviewed the whole procedure tec.) there is one point to take with a "grain of salt, the user inputs the FP value ... this is usually the number quoted by the retailer. This is a lab number, determined under controlled and very specific conditions.

IMO the odds of the product being anywhere close to that value in practical use is almost zero .... hence some form of derating is recommended/required, you either lower the input FP or you use the "over stuff" option ... either achieves the same end result, more down than the base calculation gives and moves you closer to the real down performance. If you dig into the cottage vendors, they seem to use overstuff to provide the required performance ... again, there will be a gap between the FP value the down retailer uses and the performance you will get in the field. This is not any sort of shenanigans on the vendors part, just reality that down performs differently under various conditions ... the testing is under optimum conditions and that just isn't likely in the field.

There was another post which I haven't dug up yet that suggests there is an optimum aspect ratio of baffle height to width ... that would be worth looking up. Maybe somewhere here remembers and can reference that post.
(Edit: I settled on a ratio of 2:1 or there abouts, baffle Width not more than 2x baffle Height ..... this is just a general guide and once you leave the 1"-3" baffle height range, you need to artificially/guess adjust the width)

Brian

[bikerbobber]

Make sure to peruse the DIY Stickies on here.
Also search making an underquilt on a search engine. I found a lot on Safari.
https://video.search.yahoo.com/searc...mmock&fr=aaplw
These may give insight:
http://www.tothewoods.net/RedRiverGo...GorgeQuilt.php
https://www.hammockforums.net/forum/...rchid=13187047

You can also search on You Tube as there are many tutorials to get you started.
Shug

Thanks for the suggestions Shug!

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[bikerbobber]

I have based all my quilts on the latest CatSplat calculator and they have worked out pretty well. I camp in pretty much the same locations as you and found the numbers for -5C and -20C deem to work out fine (FYI, I use a 30-40% overstuff).

After doing a lot of research into how the Fill Power is determined ( yes, I reviewed the whole procedure tec.) there is one point to take with a "grain of salt, the user inputs the FP value ... this is usually the number quoted by the retailer. This is a lab number, determined under controlled and very specific conditions.

IMO the odds of the product being anywhere close to that value in practical use is almost zero .... hence some form of derating is recommended/required, you either lower the input FP or you use the "over stuff" option ... either achieves the same end result, more down than the base calculation gives and moves you closer to the real down performance. If you dig into the cottage vendors, they seem to use overstuff to provide the required performance ... again, there will be a gap between the FP value the down retailer uses and the performance you will get in the field. This is not any sort of shenanigans on the vendors part, just reality that down performs differently under various conditions ... the testing is under optimum conditions and that just isn't likely in the field.

There was another post which I haven't dug up yet that suggests there is an optimum aspect ratio of baffle height to width ... that would be worth looking up. Maybe somewhere here remembers and can reference that post.
(Edit: I settled on a ratio of 2:1 or there abouts, baffle Width not more than 2x baffle Height ..... this is just a general guide and once you leave the 1"-3" baffle height range, you need to artificially/guess adjust the width)

Brian

Thanks for the personal experience Brian. Much appreciated.

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[bikerbobber]

Anyone have thoughts on vertical vs horizontal baffles?

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[Shug]

Anyone have thoughts on vertical vs horizontal baffles?

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I have had good luck with both but reckon I lean towards horizontal. A bit easier to migrate the down right where yo want it.

[bikerbobber]

I have had good luck with both but reckon I lean towards horizontal. A bit easier to migrate the down right where yo want it.

Great point!
Thanks for the vid!

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[bikerbobber]

Here is my plan using Catsplats calculator. Anyone see any issues?
https://docs.google.com/spreadsheets...ub?output=xlsx
Since the material isnt wide enough for the underside I have several ways to make up the difference.
I could add seams to both sides (using the cut off from the top layer) , down the middle horizontal (side to side), or vertical (top to bottom) .
Does anyone see a difference in ease of use ?
side seams.png
horizontal seam.png
Vertical seam.png

[bikerbobber]

Materials ready to go!

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