0F/-17C Optimal Sleep System – Comfort vs. Weight

[Josh]

Hi,

I am new to the community and was looking for some advice regarding designing an optimal sleep system for 0F/-17C. I for the most part have always used as light and minimal gear as possible for getting a few hours of rest before continuing on long distance multi-day runs (Zpack hexamid shelter, revelation quilt, z-lite pad) but found myself woefully underequipped for a 5-day scouting trip in the Jarbridge wilderness that saw daily snowfall and left me with permanent numbness to the medial aspect of my left toe (don’t worry no tissue, just nerve damage – so far anyway).

My questions:

Sleeping bag – I’m looking for the best weight/cost/comfort ratio, I can find and found myself looking at the Kifaru 0F Slick bag for its temp rating, wide foot box feature (I hate mummy feet), treated exterior, resilience in wet environments, and lowest weight (for a synthetic bag). I would use it with a Xtherm pad and ultralight down jacket for sleep purposes. Is there a comparable down bag for shape and treated exterior? I know there is an option of throwing a bivy over it, but I would prefer to limit the number of total items that make up my sleep system (personal preference).

VBL – is there a place for VBLs in a sleep system that only needs to be comfortable around 0F? I was thinking of just adding vest and sock VBLs to sleep clothes for weight and dropping the EN comfort rating to tolerate a 0F environment. Does anyone have experience with using an incomplete VBL system? One that essentially doesn’t create a VBL jumpsuit.

Appreciate any advice and love that there is a community devoted to this.

[Edward John M]

Easiest and cheapest VBL is simply a plastic bin liner and they do work.

A VBL shirt also works as a windproof layer. Ditto pants

I am ordering a sleeping bag from Nunatak specifically because of the centre zip but others now make them

Is that 0F/-18C stand alone or system total with the VBL suit and the LW down clothing included?

My own -4C / -8C bag has no zipper at all and is good to -25C and lower depending on the clothing worn, I am getting a bag from Nunatak to take me down to -40C

Comfort I get from my mattress system and I think yours is very marginal at -18C, personal experience and the experience of others say that the under body pad should have greater insulation value that that of the sleeping bag, in your case I’d recommend one rated for -25C as a minimum. Sleep is too important to skimp; better an extra half kilo on the pad than 500 grams in the sleeping bag

While I don’t currently own a VBL bag a VBL half bag is on the cards but I do use a Tyvek sleeping bag cover as a partial VBL on occasion and this also works well

[Ken Thompson]

https://backpackinglight.com/00277-2/

https://backpackinglight.com/ultralight_icebox_post-trip/

 

[Josh]

Thanks Ken and Edward for your replies.

The goal for my 0F/-18C system was stand-alone. The Nunatak bags look excellent. The 0F Raku is what I would be looking at but as I start to add features to the bag its price begins to climb towards that of a WM Kodiak MF which I would purchase if that were the case to maintain some resale value. I really like the idea of just integrating a plastic liner for use as a VBL in bringing my system down further.

I had to do a little research about your comment concerning my mattress system being rated to only -18C. I see something similar to this reflected in one of Richard Nisley’s posts where an R-value of ~5 pushes the EN Survival Rating to about -15C. To truly get a sleeping pad to EN Lower Comfort of -15C would require a pad with an R-value of about 8 which would be something like the Exped Downmat 9 (increased weight of about 600g, just like you said).

This puts me at 2.66kg (Slick pad, exped mat, cuben bathtub ground sheet).

Ken thanks for the two links I went through all of Ryan Jordan’s post that gave me some excellent ideas. Unfortunately Skurka’s article is locked to me because I only am paying for the peasant version of BPL, but I will see if I can get some sister info from his website.

Cheers!

 

 

[BC Bob]

In my experience, warm feet (courtesy of down socks from GooseFeetGear) make a significant difference.  A little over 2 oz.

[Edward John M]

A couple of things Josh

A centrally placed zipper is lighter and far more efficient in the real world, an UL synthetic quilt over a mummy bag seems to give the best of both worlds and personally I never buy a sleeping bag anticipating selling it.

I had Nunatak make me an UL Apex overquilt hoping that would get me down much lower but my metabolism is now much lower so I am needing a new SB if I am coming to the Arctic in Winter

Have you had time to think about whether or not you will be sleeping in clothing and socks?

Remember that EN testing is predicated on the mannequin being clad in a full layer of winter weight thermals including socks and a beanie

I’d offer to sell you my spare bag but it isn’t an UL, weight is about 1200 grams which is still light for an Expedition cut winter bag but I get the impression you want to get down to about 900grams and boost from that

 

[Josh]

Bob: I like the idea of them, but they may be something I add at a later date.

Edward: I’ll be sleeping in a full set of clothes (merino beanie, top, bottom, and socks) and was considering adding a VBL set of socks and vest. 1.2kg isn’t bad, considering the Kifaru -17C slick bag in Long is 1.6kg. Could you PM some details about your bag? Length, treated exterior, center zip, temp rating?

[Edward John M]

PM sent Josh  but no reply RU still here??

[Josh]

Hi Ed, I’m still here. Check our “Re: Sleeping bag” in your messages – I sent it the next day after you messaged me. Your bag sounds like a treasure but it isn’t the swiss army kind I think I’ll need – even though it means I’ll be looking at more weight.

[Bob Moulder]

A CCF pad of about 3/8″ thickness on top of the Xtherm adds a huge amount of warmth. I’ve used an Xtherm Max down to about -5°F and found that for me it needed some “help” to achieve a real comfort rating at this temp, which it did — totally comfortable. How much lower it can go, I don’t know.

I know you’re looking at bags, but perhaps a quilt can work for you and offset the additional ounces for the CCF, which is approx 7-8oz. As has been noted ad nauseum, with a bag the fill on the bottom is compressed by body weight and doesn’t add much insulation anyway. Enlightened Equipment’s lowest temp rating for an Apex quilt is 20°F, but maybe(?) they’ll make an Enigma Apex rated 0°F for you.

For a bit of wind/precip protection, a Zpacks Pocket Tarp and polycryo groundsheet could be added for a total of about 6-7 oz including stakes.

 

[Eric Blumensaadt]

1. TENT-> SCARP 2 or Moment DW – both winterized W/ internal crossing poles, etc. (My tent is part of my sleep system.)
2. LL Bean -20 F. down sleeping bag (best designed winter bag I’ve ever owned)
3. Thermarest TrailPro mattress – W/ Ridgerest CCF mattress under if below -20 F.
4. light fleece balaclava
5. thin poly glove liners (Don’t laugh, they’re more comfortable than bare hands.)
6. heavy sleep socks
7.  Polar air warming mask if -20 F. or colder (keeps my nose warm too – a very important factor)

[Edward John M]

About time for some feedback isn’t it Josh??

[Josh]

Hi all,

Thanks for all the pointers and advice. In altering my system to truly accommodate my height (6’2″) and my tendency to be a cold sleeper I sold my ZPack Hexamid (too short), replaced my regular length EE 30F quilt, and ditched my Klymit Static V2. Via our BPL gear swap and ebay I ended up with a sleep/shelter system total weight of 7.6lb:

1. YMD Cirriform 1P+ Tarp – (16oz)
2. Hiker Hunger poles (15oz)
3. Kifaru 0F long slick bag – synthetic (57oz)
4. NeoAir Xtherm (16.5oz)
5. Cuben bathtub ground sheet (3oz)
6. Merino top and bottom base layer (14oz)

On a recent 4-day with a low of 15F/-9C and moderate evening fog, I found myself incredibly warm and had the center zip down to my mid-chest. Given the ventilation of the tarp there was no condensation on the tarp or my bag. Not included in the weights above are an extra pair of hiking socks (wool injinji), thin glove liners (thanks to Eric for this pointer – it truly made a difference!), and the buff I wear while hiking.

I will still need to test this further but this is the first hiking / long distance running multi-day trip in which I did not have a miserable sleep. So thank you all for that! This was something that was often the case in the past due to a preference for gear that would allow me to run without a lot of pack bounce and could get down to about 20L in size. Suffice to say this was one of my more enjoyable trips I’ve ever had.

There’s room for improvement in the future but this felt like a good start. It was also my first experience with a tarp and I have to say far outstripped the half-dozen ultralight tents or bivys I’ve tried. I’d like to bring a CCF pad on my next multi-day, as suggested by Bob, to test it out when temps are sub-zero.

In reference to quilt vs. mummy, I flop around like a fish in my sleep and the large semi-rec style of the Kifaru bag lets me do just that without constantly creating a draft pocket or using a bag liner for comfort. The synthetic choice had to do with a 6-day highland backpacking trip where constant low cloud cover had everything damp by the third day and I was ready to just burn my gear and walk off the mountain.

When finances permit maybe in a few years, I’d like to pursue a custom order like Ed and get a Nunatak 0F center zip. I’ve had all types of bags and the center zip has to be my favorite.

[Edward John M]

There is an UL down half bag for sale in the gear-swap section, it would make an excellent booster for the Slickbag and the price really is a bargain

[Author]

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