new bag offering from Nunatak

[Mike M]

I talked with Jan a couple of months ago about a down bag, sans zipper.  He had the Akula half bag, but I wanted something full length (74″) and needed it to be wide enough in the upper portion to get a lighter insulated on.  It’s 62″ at the shoulders and tapers to 40″.

We talked about fill weight, I wanted something in the 35 degree range and Jan suggested 11.5 oz of 900 fill.  Looking at similar cut bags and fill amount from Western Mountaineering, Feathered Friends, Enlightened Equipment, Zpacks and others- it appeared that amount should be very comfortably in that range.

He used 10d for both inner and outer.  The bag came out to a very svelte 17.9 oz :)

I’ll be testing it out in a couple of weeks on the Wonderland Trail, but if it’s anything like any of his quilts/bags- I should be good to go.

I don’t think it’s on his site yet, but he dubbed it the Sastrugi and am guessing like most of his products will offer in a variety of lengths and temp ratings.

Anyways, a zipless bag isn’t for everyone, but guessing it might be of interest for a few folks here :)

[BlackHatGuy]

Looks nice. Looking forward to hearing how it works out for you.

[Adam Kilpatrick]

Nice!

I guess if sized to work with an insulating piece, then you have a bit of temp range flexibility by taking that off.

PHD has always offered zipperless superlight bags. With short and full length zip options. Interesting in the last couple of years (or maybe more?) they offer an option to put in a very short zip on the side of the footbox to vent. This keeps a proper footbox, and makes the zip very light and simple. Not sure how much temp flexibility it gives but could be maybe 5F?

If you think about it for your bag, at ~35F comfort limit, cinched up, you probably have 5F or so of range of not getting too hot, so thats 40F. Loosen up the top of the bag, but still over your shoulders, its probably 45F. So that’s maybe the upper? Of course you can move the bag down giving you more venting at the top.

Add in your insulation piece and you start going lower.

 

[Mike M]

Yeah definitely lose some venting options with a zipless bag; good thing is I rarely see temps above 45 for nighttime.  I have a 50 degree quilt that I’ve froze my a$$ off three different times, so it’s been relegated to cold weather as an over-quilt :)

[Edward John M]

Zipperless bags rock. As does the extreme tulip shape.

I’ve been looking at buying a FF Vireo for a while myself but they are just a touch too small for me and now I don’t think I’ll ever need one

 

[Jon Solomon]

I used a first generation FF Vireo quite often on trips where I was sure that I would be hiking in a predictable temperature range. The convenience, simplicity, and warmth in use was a joy. Glad to see Nunatak add this as an option. Wouldn’t be for me, though, as my main usage nowadays (Pyrenees and Alps, etc) requires greater flexibility that only a quilt can offer.

[John S.]

I still use the RAB Quantum Top Bag. (hoodless, zipperless, no down on bottom, less down at 7 oz)

https://backpackinglight.com/rab_quantum_top_bag_sleeping_bag_review/

[Mike M]

this should open some options for folks that are looking at either the Vireo or Tanager, as Nunatak will likely offer it in multiple configurations- width/length/amount of fill; this one doesn’t use a differential fill like the Vireo, but am guessing Jan could accommodate that if someone wanted it

interesting on the RAB Quantum- funny I’ve never seen that before you posting it, sounds like a very interesting idea :)

[John S.]

The earliest versions of the RAB bag had mesh on the bottom. Then the Quantum model came out with solid fabric on the bottom.

It would be interesting to see what a Nunatak bag would weigh with maybe 8-9 oz of your down, those updated fabrics and a smaller bottom portion of fabric without down, to eliminate or lessen drafts…maybe around 11 or 12 ounces.

[Mike M]

^ it would be pretty darn light, that’s for sure- 2.5-3.5 oz of less down and like you said less material on the bottom

it sounds like RAB made their bottom 22″ which is kind of an in-between size for pads; narrowing that down some to reduce drafting- you’d have a very svelte piece of kit :)

[Geoff Caplan]

I’ve never understood the idea of a differential fill, especially on a hooded bag.

When you turn on your side, surely you end up with a cold back? It’s not like a quilt where you turn under the covering – the bag’s going to be turning with you.

That’s a lovely bit of kit, by the way. As I said recently in another thread, I’ve used zipless bags in Florence in August and it felt fine. I’m seriously thinking of going back to one for the lightness and simplicity. But people’s needs seem to vary pretty widely when it comes to sleep comfort. The PHD foot-zip or a drawstring closure at the foot would add a bit more flexibility if you felt the need without adding much weight.

[Mike M]

I was talking more about differential fill like the Vireo uses- less in the upper portion (waist up), more in the bottom half (waist down)- idea being you would use a puffy to even things out.  The vireo is rated at ~ 45 degrees on the upper portion, 25 on the lower portion.

I’m guessing on the Quantum you would want to use the bag like a quilt and roll inside it- keeping the bottom that has no fill, on the bottom- maybe John S can shed more light on how well it works

[BlackHatGuy]

“The PHD foot-zip or a drawstring closure at the foot would add a bit more flexibility if you felt the need without adding much weight.”

I only buy quilts these days that have this capability. It immediately cut down/often eliminated wetness in the bottom of my quilts when I did.

[Geoff Caplan]

Mike – the upper/lower body differential fill is quite an interesting idea, especially for someone who suffers from cold hips and an overheated chest, like me!

MLD do a quilt like that, aimed at fastpackers: https://mountainlaureldesigns.com/product/fkt-quilt/

Going to play with some calculations and see how much weight it would save.

With a Karo Step MYOG bag you could get much the same effect just by moving the down around – would be more flexible than baffles with a fixed differential fill.

[Mike M]

yup- the FKT from MLD is the same exact idea :)

 

 

[John S.]

Yes, on the RAB you must turn inside the bag. I use it with a water resistant bivy to eliminate drafts. Those are two downsides to some backpackers.

[Chris R]

Interesting you mention the foot box zipper on the PHD bags. I’m pretty sure I got them started on that design. I requested a short zipper in the foot box of Minim bag they sewed me 15ish years ago when I lived in the UK. I also had them sew me an ultralight bivy/bag protector using the same water resistant fabric they were offering in some of their expedition bags.
wasn’t the idea of the Rab top bags to put the pad into the bottom of the bag?

[John S.]

Chris R, you could be right about that. The RAB bag inside dimensions are bigger than a typical sleeping bag. I have used it over liner type bags for additional warmth in winter.

[Geoff Caplan]

“The RAB inside dimensions are bigger than a typical sleeping bag”

I suspect that’s why these bottomless bags with a sleeve for the pad have never really taken off. Unless you’re very smart with the design, you’re going to get a lot of dead-space inside the bag which will make it cold and inefficient.

At a quick look, Rab, Thermarest have discontinued their bottomless bags, but Big Agnes still lead on them. I can’t see how their system works unless you spend the whole night on your back. If you’re a side sleeper, surely the hood is over your face?

Plus you can’t sit up in your bag, or even draw up your knees.

Nice theory – hard to see how you can make it work in practice.

[John S.]

Geoff, I use all bottomless bags with a pad outside the bag, just so I can sit up. It may make it less efficient, but I am okay with that because I use it with a breathable bivy.

I have grown to love the RAB inside dimensions being larger so I can turn inside the bag, wear more clothing, use it over a liner bag, etc. To me it’s very versatile. Fifteen years use of one piece of gear is not too bad. I even bought a second one as a backup.

[Edward John M]

I have to ask if you are/were unhappy with the FF Flicker you got a short while ago?

Is this new bag a replacement or just another arrow in the quiver?

Given your positive feedback on the Flicker I was thinking of one of those rather then the Vireo but I bought a S2S Traveller2 in a Long/Large on sale, 0C and just a 100 grams of extra weight compared to the Flicker Extra wide and saved $250- [ exchange rate and postage cost]

[Mike M]

My Flicker is rated to about 10-15 degrees (2o degree w/ 3 oz of overfill), so it’s my late fall/winter (usually w/ a 50 degree Apex quilt)/early spring bag.  It’s pretty light @ 28 oz considering it’s rating, but wanted something lighter for “summer”.  The Nunatak is a solid 35 degree bag (probably more like 30- we’ll see) and weighs under 18 oz.

So no, not unhappy with the Flicker at all :)

[David U]

Thanks for this thread Mike.  Most interesting.

 

I have been using my Flicker (20 degree with 3 oz of overfill) for every trip in the Canadian Rockies, mostly because of the massive temp swings.

Curious – did you ever consider the 40 degree Flicker?

[Mike M]

I did, the 30 too.  I don’t think the 40 would have been warm enough w/ 8.5 oz of fill, I could add a couple of ounces of overfill, but then you’re probably better off getting the 30 degree bag.  The 30 Flicker has 11.5 oz of fill, the same as the Nunatak- so should be in the ballpark for warmth.

No doubt the zipper would come in handy at times I’m sure.  If I find I’m wanting for a zipper more than I think I will- I’ll look into adding one :)

[Alexander L]

I’ve been in touch with Jan and seriously thinking about getting one of these instead of a quilt. I’m predominantly a side sleeper so I thought a quilt would be my best option but I don’t like any of the strap systems. I prefer simple designs. My thinking is that I really only want the option to open up a bag in really warm weather, in which case a traditional quilt would work fine and I would not even bother with attaching it to a pad as there’s no issue with drafts.

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