Multi-configuration underquilt

[JShep]

So I've been a long time reader here but this would be my first post, so go easy on me if this has been discussed to death (despite an exhaustive search that turned up diddly) or if this is the wrong place for the post.

For quite some time now I've been toying with the idea of one piece of sleeping insulation gear that can be used in multiple scenarios. For example, something that can be used as an underquilt, or taken off and zipped up as a sleeping bag when a hang is not appropriate. My wife and I do a lot of backpacking and camping together so I would like something with opposite zippers so the two "bags" can be zipped together and thrown on an air mattress for a queen size sleeping bag. These three requirements are what i'm primarily after but if it was at all possible to go one step further and separate the underquilt and configure it as a top quilt for use with a ground pad that would be even better, but this is probably the least used sleeping arrangement, so if it over complicates things it'll be the first to go.

I'm looking to use 850fp hydrophobic goose down, i'm 6'4 and my wife 5'10 and I need these "bags" to be ~15 deg. This adds up to a lot of down approx $500-$600 worth, the high cost is partly why I don't want to make separate bags and quilts for each individual scenario. Has anyone seen such a design that's still effective as both an underquilt and a sleeping bag? I've seen a few on amazon and such but the designs look terrible. I haven't used an underquilt with my hammock just yet (we live in Texas and it just hasn't gotten cold enough on a trip yet to need it) but my wife and I are planning a 9 day BP trip through rocky mountain NP for 2020 and it will be necessary then. Thus, i'm not sure exactly how my wife or I would like it set up, however I figured the fabric is significantly cheaper than the down so if i don't like the design or configuration I can always start over with new fabric and just re-use the fill. My wife and I are avid DIY'ers and have a number of sewing projects from hammocks to garments under our belts so i'm fairly confident we can handle such a task.

As for the design....
Since these would be used for backpacking weight and pack size is a bit of a concern, however we are currently packing old 5lb & 5.5lb synthetic fill 30 deg bags so just about anything would be lighter than this. My "bag" will get used about 60% of the time as a sleeping bag while my wife's will be used more as an underquilt. Since I would like these to zip together for a queen size double sleeping bag they would need to be the same length, and also width since our hammocks are both the same width. This being said, i'm looking at an 80" x 72" rectangle with ~2-2.5" tall baffle & 10-15% over stuff. I'm thinking two separating zippers, one for the long side and then one 36" long for the foot end the would be zipped only in the sleeping bag configuration. On the foot and head end, is a sewn channel with an adjustable elastic chord running through (this would be below the zipper on the foot end), the elastic would be wrapped around the ends of the hammock and adjusted to control airflow. Sewn to the channel would be a series of buttons to allow for a clew to be set up in the underquilt configuration. I would also include a removable hood that can be zippered on for sleeping bag, or removed and worn independently in a hammock.

I've been using the calculator provided by CatSplat, Provided by https://ripstopbytheroll.zendesk.com...my-underquilt- which gets me approx 15 degrees with a 2.25" baffle height and around 30oz total weight (i'm expecting more like 40oz once the zippers and cordage are added in). However, this is just a reference guide so can anyone validate its accuracy with regards to temperature rating? It looks like its assuming just a modified rectangular baffle design, which i don't plan to use.

As for materials, I tend to sleep pretty warm and may sweat a bit while my wife is just the opposite. So I will need something very breathable and soft for the inner shell and my wife something still soft but maybe a bit less breathable. I'm not sure which would be better, Nylon or Polyester based, but i'm considering Argon 67/90 or Ion from dutch or HyperD or one of the Membrane products from RipstopByTheRoll. can anyone speak to these materials for their softness & breath-ability? For the outer shell, i'm considering something a little heavier to handle the wear and tear, possibly Argon 90? Ideally i'd like something that can be waterproofed around the ends or at least shed water fairly well. For the baffle wall materials, i'm going as light as possible, probably a 0.5oz noseeum.

I realize this is a'lot of questions for one post but what can I say, its my first quilt and i want to get it right! thanks in advance for any help / insight!

[Smckinney0031]

I am so totally clueless but I just wanted to tell you that I seriously admire the thought you have put into this!

[makingitoutdoors]

Sierra Madre makes the puffle that does these conversions but is only 40° so won’t fit your needs.

I’ve only made apex underquilts so I don’t have much else to contribute. I’m scared of down.


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[JShep]

I am so totally clueless but I just wanted to tell you that I seriously admire the thought you have put into this!

Thanks! I'm a design engineer so the thoughts and details are where I live. That and i'm incredibly passionate about product development so I literally cant sleep at night when I get caught up thinking on a new project. My wife hates it cause i'm always tweaking and making things just a little better.

Sierra Madre makes the puffle that does these conversions but is only 40° so won’t fit your needs.

I’ve only made apex underquilts so I don’t have much else to contribute. I’m scared of down.


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The puffle is a pretty good starting point, there's a few tweaks i'd make though.

I've never worked with down so what makes it so scary?

[TxAggie]

I like your thought process, but what I’m not understanding is why you would want to use your underquilt as a sleeping bag when you already have a top quilt, Most of which are equally suited for ground or hammock use. If you want to join them to make one large quilt for sharing, I would think most of our cottage vendors would be willing to make a set of zippered footbox quilts that can be paired together.

Enlightened equipment actually makes a double quilt, but that would only be useful when you’re on a shared mattress as you’ve described.

Personally, I’m actually working on a design for down overalls that can be converted to a top quilt liner.

Good luck on your quest.


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[makingitoutdoors]

[QUOTE=JShep;2002521

I've never worked with down so what makes it so scary?[/QUOTE]
The investment for one. I’m scared of just puffing it all over the house or it migrates and isn’t actually warm.

I’d like to make a hood, beanie or booties first.

[JShep]

I like your thought process, but what I’m not understanding is why you would want to use your underquilt as a sleeping bag when you already have a top quilt, Most of which are equally suited for ground or hammock use. If you want to join them to make one large quilt for sharing, I would think most of our cottage vendors would be willing to make a set of zippered footbox quilts that can be paired together.

Enlightened equipment actually makes a double quilt, but that would only be useful when you’re on a shared mattress as you’ve described.

Personally, I’m actually working on a design for down overalls that can be converted to a top quilt liner.

Good luck on your quest.


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Because I don't have a top quilt, just a regular old synthetic fill sleeping bag. I don't intend to use a top quilt either, at least not while backpacking we'll probably just sleep in our down jackets. However, the idea of simply making a zip on footbox to enclose a quilt to a sleeping bag is something i haven't thought of. It would make it easy to convert between the two and still have all the bedding materials.

One scenario that keeps coming to mind while backpacking in the mountains is that there aren't always trees or rocks to hang from, especially when you reach higher elevations. My hope is to make an oversize winter tarp that could be folded and staked in such a way to make a tent when needed. Our preferred sleep is in a hammock but i'd like to have a backup for when we cant hang. Having the convertible quilt helps in these scenarios without having to bring extra gear along.

[TxAggie]

Because I don't have a top quilt, just a regular old synthetic fill sleeping bag. I don't intend to use a top quilt either, at least not while backpacking we'll probably just sleep in our down jackets. However, the idea of simply making a zip on footbox to enclose a quilt to a sleeping bag is something i haven't thought of. It would make it easy to convert between the two and still have all the bedding materials.

One scenario that keeps coming to mind while backpacking in the mountains is that there aren't always trees or rocks to hang from, especially when you reach higher elevations. My hope is to make an oversize winter tarp that could be folded and staked in such a way to make a tent when needed. Our preferred sleep is in a hammock but i'd like to have a backup for when we cant hang. Having the convertible quilt helps in these scenarios without having to bring extra gear along.

Got it, makes sense. I’ve thought about these things as well, and though I’m a solo camper I’ve worked out some contingencies:

The Warbonnet Superfly works GREAT as a ground shelter. If anything, it’s almost too long. But you should be able to fit two plus gear underneath, especially if it’s not terribly windy and you don’t need to have it staked fully to the ground. The doors can even be fully closed to keep out rain if needed.

Second, I’ve started carrying the short version of the Neo Air for backup, both in case overnights drop below the 40° rating of my 3/4 UQ and on the off chance that I do need to GTG. The extra 8oz isn’t too terribly bad. Then again combined with whatever top quilt/sleeping bag I have I should be covered.


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[SilvrSurfr]

Because I don't have a top quilt, just a regular old synthetic fill sleeping bag. I don't intend to use a top quilt either, at least not while backpacking we'll probably just sleep in our down jackets.

I wouldn't recommend going without a topquilt. A few years ago, we had a group hang in the NJ Pine Barrens, and it got down to 17* F. I woke up around 4 or 5 am to water the bushes, and found a guy shivering by a tiny campfire. He said he was freezing to death. I knew he had just bought a brand-new 0* underquilt, so I asked him how he could possibly be cold with that. "That's all I brought - I didn't bring a top quilt because I didn't think I'd need it." Lesson learned!

The only other person I've ever heard even suggest going without a topquilt is one of our resident trolls, Trecker8, who suggests you bring battery clamps for your UQ and then you won't need a TQ. Sounded pretty funny to me, so I actually looked up on Amazon how much a battery clamp weighs (6.7 ounces). So for the weight of three battery clamps, you could actually carry a 20* topquilt instead.

https://www.hammockforums.net/forum/...a-nice-to-have

Then there was the guy (Rockets Redglare) who thought you didn't need an underquilt - just hang over the dying fire.

https://www.hammockforums.net/forum/...ang+dying+fire

Rockets Redglare also once said you don't need any insulation or even a tarp - just use HVAC flexible ducting.

https://www.hammockforums.net/forum/...e-A-Flexi-Duct

If you do try to go without a topquilt, make sure to test it out in the back yard. I don't think a down jacket for top insulation is gonna cut it. Just like you'll never catch me hanging over a dying fire or using battery clamps!

[Phantom Grappler]

SilvrSurfr, Lol, some only learn by personal trial and error—always reinventing the wheel.
That reminds me of the guy who was gonna cold weather hammock with no insulation. He was gonna leave quilts at home and rely on scientific studies of thermogenesis. He was gonna raise his body temperature by ingesting half dozen jalapeño peppers every night...

All in fun, hammocks are great fun
I had fun with that lie
Everything worked in theory
Like my fails to win “Purdy Boil” contest