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Ice Raven - Sub Zero Adventure
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Sub Zero Sleeping System

The old Sleeping system set up in a quinzhee - Ice Raven - Sub Zero Adventure - Copyright Gary Waidson, All rights reserved.

Just finished a couple of modifications to my Sub Zero Sleeping System ahead of  our upcoming trip to Kittilä, now scheduled for February 2023.

 The old system, with a Brit Army Bivi bag worked fairly well but the Goretex stopped breathing at low temperatures which resulted in ice forming  on the inside which in turn transferred dampness to the synthetic mid layer  sleeping bag.

Not too much of a problem but not ideal.

Sub Zero Sleeping System - Ice Raven - Sub Zero Adventure - Copyright Gary Waidson, All rights reserved.

The new Shell bag is made from Ventile which while not being quite as  "waterproof" makes up for it in a cold environment by being much more  breathable. I made this bag some time ago but haven't used it much  because it was awkward to get in and out of. I've improved that now with a water resistant zip on the side.

Sub Zero Sleeping System - Ice Raven - Sub Zero Adventure - Copyright Gary Waidson, All rights reserved.

The rest of the system remains pretty much the same. A down filled inner bag for maximum warmth to weight ratio.

A synthetic mid layer bag which is less damp sensitive as condensation may start to occur in that layer.

Finally the new Ventile Snow Shell.

Underneath all that I have a 9cm inflatable down mattress sitting on a folding foam mat for puncture protection.

The other essential part of this system is a tubular hood made from a microfibre towel.

This is used to absorb moisture from breath which could otherwise condense in the sleeping bags or shell compromising their insulation properties. It can be dried out during the day much easier than the rest of the system.      Simple but effective.

Sub Zero Sleeping System - Ice Raven - Sub Zero Adventure - Copyright Gary Waidson, All rights reserved.

Of course, it wouldn’t be me if I didn’t add a bit of decoration so I finished off the top with a bit of jacquard tape.

Home made Schnozzle for Exped Down Mat - Ice Raven - Sub Zero Adventure - Copyright Gary Waidson, All rights reserved.

The Down Mattress was a game changer for me. I had always struggled to get comfortable on closed cell mat or thin air mats but the down mat is almost as comfortable as my mattress at home.

The only down side is that it takes quite a bit of effort to fill in the cold.

There is a hand powered pump built in but it relies on a foam filling to operate and that tends to be sluggish when cold.

The manufacturer makes a dry bag that has a nozzle that attached to the inlet valve to fill it faster but charge a premium for it.

So, enter the humble cork, this one big enough for a demijohn used for brewing.

A few holes drilled through for airflow and then tape it into the corner of a strong bin liner and hey presto. One home made pump bag which works a treat.

December 2021.

Sometimes the unexpected comes along and gives you a wee kick in the butt. A couple of days ago I decided to check on the sleeping bags which I had not inspected since last year when I took the picture you see on this page illustrating my layer system.

As you can see, at that time everything was fine. This year I picked up the synthetic bag and it was immediately clear to see that the insulation had collapsed. There was no loft at all and the bag was only about 10-15mm thick all over. Not good...

I know synthetic bags have a more limited lifespan than down but I was shocked to see how suddenly it had failed.

To be fair, the bag is over 12 years old so I should not have been surprised but I usually  hammock in the summer and my sleeping bags only really get used in winter. Over the C-19 lockdown these bags had not been seen at all.

They are stored in large drawer / boxes where they are loosely packed and not compressed so this must have been some kind of natural breakdown of the fibres. Hey ho...

I was certainly glad I had checked when I did, because had this been just a week before the trip things would have been somewhat more urgent.

As it is I have ordered another synthetic bag, I still like the idea of having a combination, and this bag has a much better temperature rating ( Comfort -35c Extreme -45c ) Such ratings are usually optimistic to say the least but it should certainly out perform my old bag and depending on conditions the bags can either be used individually or in combination to cover a wide temperature range.

It is of course a bit heavier and bulkier but as I get older I appreciate a comfortable nights sleep a little more than I used to. I will be able to report more on it’s performance after the trip of course.


Sub Zero Crew - Bushcraft UK

Unless noted otherwise, all photography, artwork and content on this site is copyrighted. © Gary Waidson 2020 All rights reserved

The Ice Raven Project promotes sustainable and low impact bushcraft and wilderness skills in Arctic and winter conditions. This includes the use of  tents, tarps  and snow shelters where possible. Fires are only used where safe and where use and collection of firewood will not damage the natural environment. We often travel to locations by public transport and then use snowshoes, sleds, toboggans and pulks to transport our equipment into the wilderness.