20 deg too drafty for quilt?

yeah, connect the two sides underneath with silnylon.  Sort of like a bivy except the top is a quilt.  No drafts at side or foot.

I keep screwing with this, not happy yet with the collar that prevents drafts coming through at my neck and shoulders.

My goal is 4 inch baffles, 2 inch loft, 16 ounces, 20 F if I wear some extra stuff inside

Timmermade do a “false bottom” bag with that concept. A few others have similar concepts. I know some lightweight sleeping bag companies will also put less down underneath.

No personal experience with these concepts. It’s been so long since I’ve used a mummy bag I couldn’t accurate guess at the performance. But my fear is that with my tossing and turning I’d throw the uninsulated/lightly insulated patch up behind my back or over my chest and wake up cold and tangled.

Michael

Back when I used my bag as a bag, it was very frustrating to roll over but not have the bag follow me so that my face would still be in the opening.

I think I’ve figured out the solution to that.

A lot of mummy bags, even by good manufacturers, don’t have a draught-collar and draw-cord closure here, round the shoulders:

This is inefficient, as it allows heat to escape, and it leaves the shoulders free to turn inside the bag, leading to the face-in-hood experience that you mention.

If you use a bag with a draw-cord like the one below, any time you are using the hood you draw the bag tight around your shoulders, trapping in the heat and ensuring that it turns with you during the night.

Since I figured this out, I’ve never had a face-in-hood incident…

Opogobalus reminded of the Timmermade false-bottom bags:

http://www.timmermade.com/store/p76/Thrush_false_bottom_sleeping_bag.html

Dan is claiming that they work out even lighter than a quilt, because you don’t need so much width. With the 950fp down, the 20F bag is working out at 19.4 oz / 550 grams which is impressive if the rating is accurate.

That’s for the drawcord footbox, which offers more flexible venting than the sewn footbox, which comes in an ounce lighter.

Of course for cold-weather use you’ve got to add the weight of a hood, as you would with a quilt.

I pinged Dan and asked him about the bag turning with you and leaving your butt exposed. He says that he personally doesn’t find that an issue, but if you do turn in your sleep you can strap the bag to your pad:

Looks like an interesting third option that sits between the standard quilt and the traditional mummy.

Has anyone used one? A very positive review here:

https://www.reddit.com/r/Ultralight/comments/epasyv/timmermade_quilts/

Noticed that he also offers an Apex jacket. Worth passing on, now that Nunatak have discontinued their Apex products.

Your drawcord solution might help with the “false bottom” quilt idea and the drafty bum issue. I don’t have many issues with drafts with my wider-than-normal quilt, but:

1) I think i’ve learned to make sure I don’t throw the quilt off me when turning.

2) The closed footbox really encourages the quilt into the right shape

3) if it’s cold enough that drafts will be an issue I’m nearly always with a bivy anyway. I use a tent with a mesh inner when bugs are an issue (when it’s relatively warm), or a mid with a bivy when they aren’t (which is usually in colder weather here).

My partner is going to sew a “false bottom” onto her quilt at some point – she’s an almost unfathomably cold sleeper.

—

His apex SUL jacket concept looks curious. Fairly niche use, but curious. I like the idea of the “mesh” inner liner.

If you use a bag with a draw-cord like the one below, any time you are using the hood you draw the bag tight around your shoulders, trapping in the heat and ensuring that it turns with you during the night.

If you really mean a drawcord around your shoulders vs above them (i.e., base of neck), I can say that I’d never heard of bags with that feature (though haven’t looked at bags in 10 years) and believe I would not like that at all. It’s clear there isn’t a one-size-fits-all solution to this issue. :)

Big Agnes also does false bottom bags.

Long ago my sister had a bag that consisted of a down top and thin layer of synthetic insulation on the bottom. Not so much to save weight as to resist compression and moisture from a cold damp ground and to save money. Not quite done right it was interesting to consider. Eventually went to a down inner and a poly outer for sub zero temps. I roll around a lot and having a synthetic outer all the way around made sense for dealing with moisture buildup and did add a bit of  cushion and insulation underneath

I just made a batch of roomy quilt/bag covers with sil on bottom and dwr on top with a mummy style hood. No netting, it is for shoulder seasons to beef up the quilt/pad system. The idea is to put the pad inside to keep it on place and the sil bottom replaces a ground sheet you might carry anyway, the top keeps out drafts, dust and such and gives you a place to store gear/clothes. In a pinch you could flip the bag over for short term rain protection. Cheap enough to project your quilt investment. I call it the Cold Weather Quilt Cover.

Michael

I obviously wasn’t clear enough – yes, I meant a draw-cord around the neck that closes the bag above your shoulders.

My bag also has a fairly modest neck collar – not sure if it does much beyond adding some padding to the draw-cord, but I don’t think it weighs much either.

The Big Agnes system is very different from the Timmermade, with a sleeve that wraps around your pad. Never used one, but it seems to me you’re going to have a very wide bag with a lot of dead space you’re going to have to heat up. The 20F Regular weighs over 1kg at a similar price point to the Timmermade – I think it’s an inherently heavy and wasteful design.

I call it the Cold Weather Quilt Cover.

Is it not the same as the modern UL “splash bivy” (i.e. a bivvy not for being in the rain, but for being under a tarp, and mitigates any dribbles of rain, snow or wind that might make their way in)? Or is there a part I’m missing?