Bivy options with Snugpack softie

[Erbswurst]

The Special Forces 1 is designed to go with the Special Forces bivvy bag. To have both zippers over each other is optimal. And central zippers are optimal, especially if you don't use a modern tent.

The bivvy bag adds approximately 3°C to the sleeping bag. Who uses a bivvy bag usually keeps the clothing on if he goes to sleep and if they aren't whet. Or he will change into dry spare clothing.
The average clothing in the evening around the freezing point and the bivvy bag boost the Snugpak Special Forces 1 down to the comfort limit of approximately 0°C.
Below this temperature starts real winter camping and people would take the Special Forces 2, a larger rucksack and generally slightly different equipment.
Thats why the SF1 in the whole bivvy bag sleep system works comparable to a warmer side zipper sleeping bag that's designed to use it in a tent.

And if you aren't a pure summer camper it's quite interesting that the SF1 is part of the modular Special Forces complete system. Together with adapter and SF2 you can create a very warm but very comfortable sleeping bag for really cold weather with a perfect warmth regulation.

The Special Forces System is Snugpak's top model and one of the options that's issued to NATO armies. If NATO soldiers get something else it's usually the Carinthia modular System Defence 4 + Tropen + Bivvy bag or a copy of that or the similar US army system.
The Snugpak system is in my opinion the best choice for civil users. If you search you will find in this forum my detailed descriptions of these systems in comparison.

I wouldn't buy a bivvy bag with a side zipper. That can't work properly. If you have such a weak point it has to be located under the other one directly under your nose. Like this you can roll onto the side and protect both against heavy rain.
That's impossible with a side zipper.
You either would expose it to the wind or put it in a pool underneath you.

I generally recommend to look first what's currently issued to NATO armies. What's issued to the most ones is usually the best option. If there are differences they are usually due to the weather conditions in the different countries.

Everything else is usually a less good option if we talk about general purpose items. The civil market offers you all and everything because they earn the more the more errors the clients make. The military surplus market offers you stuff that simply works. If you get this equipment factory new you get the best of the best. Exceptions from this rule are very very rare.

Most military sleeping bags have a central zipper.

 

[Erbswurst]

Regarding the clothing that experienced woodsmen wear if the Snugpak Special Forces 1 comes to its limit I opened this thread here:

Base layers from which temperatures on?

At which temperature do you put on longjohns if hiking and wildcamping? Let's assume that you wear over it only the usual polyester - cotton mix trekking trousers or the usual army field trousers.

bushcraftuk.com

 

[Joeking]

Is there space for a mat in the SF bivy? A lot of people seem to favour this set up.

 

[Joeking]

Like this you can roll onto the side and protect both against heavy rain.
That's impossible with a side zipper.
You either would expose it to the wind or put it in a pool underneath you.

Sounds like this set up doesn’t have mat in bivy? Surely if you want a mat in your bivy, you have to wriggle around in side to stay on it not roll over the whole bivy. Under this set up wouldn’t a side zip be preferable?

 

[Erbswurst]

The bivvy bag is a waterproof second skin for the sleeping bag and there belongs nothing in than insulation material that wicks moisture away from the person and small items that need protection from freezing like electronics and water bottles and perhaps cleaned boots if we talk about winter camping. And if you want a modern military rifle. You may put off some clothing and stuff it to the bottom of your sleeping bag as also that falls into the category wicking insulation material.

The Snugpak SF bivvy bag fits exactly around both SF sleeping bags together and the adapter and the man inside. He may wear a complete winter uniform also with the padded suit and boots. That's military equipment and they assume a relatively athletic body shape of course. But compared to modern mountaineering sleeping bags the cut is pretty wide.

Civil persons do what they want with their equipment. I assume that some put the head into the foot box and let the naked toes look out. But although I spend a lot of time in such forums I am not willing to discuss such alternative options.

The closed cell foam mat belongs under the bivvy bag to protect it against little thorns and sharp stones. It also keeps the bivvy bag clean. Dirty equipment doesn't work properly.

Some experienced people who want to use an insulating airmat put it into the bivvy bag to keep it warm. Like that you can perhaps avoid ice in the airmat with good luck.
In my opinion it's a bad compromise and I wouldn't do that. In this case you obviously need to use a tarp over you because you can't roll around anymore.

Unless you have to sleep regularly directly on stones, whyever, I can see no reason to use an airmat.

If you sleep in the open field in heavy rain and wind in your bivvy bag you have to roll onto your side, the nose pointing in a 45 ° angle to the ground. That's the only way to breath out and protect the breathing hole against rain.
That can only be done with a bivvy bag without zipper or a bivvy bag with a central zipper and flap over it.

A side zipper in the bivvy bag would get into the puddle underneath you and the puddle would enter your sleep system.

You should try to avoid such a puddle of course by choosing an elevated sleeping place and putting only the closed cell foam insulation mat underneath you and no larger waterproof plastic sheet.

But nevertheless there will always float a bit water under your body.

 

[Erbswurst]

If you sleep in a tent you can connect two sleeping bags with zippers at the different sides. That can be life saving in the mountains where people tend to choose the lightest options and can't find firewood. In connected sleeping bags mountaineers can warm each other.

That system was or is also issued in the Swedish army for example because they count in temperatures that would demand incredibly bulky and heavy sleeping bags for the single man.

But most civil sleeping bags are only equipped with side zippers because it is far cheaper to make them. They tell you you can connect them, it sounds romantic, and people buy the stuff.
But two persons in a huge sleeping bag will never sleep as comfortable as in two single sleeping bags in normal circumstances. You always wake up the other with every motion.
And if you use a single sleeping bag with side zipper that isn't fully closed, you always get a cold shoulder if you sleep on your side.

That's why the standard military sleeping bags have central zippers.

The tropical military sleeping bags have side zippers, because like that you can better close the head hole with a moskito net. If you want moskito net and bivvy bag you haven't the both zippers over each other. That's sad but there is no better way to do it.

And in tropical conditions a cold shoulder isn't such a problem.

The standard military sleep system in Europe is the Carinthia Defence 4 with Carinthia Goretex Sleeping Bag Cover with central zipper.
Some countries issue other bivvy bags due to different weather conditions.

The Snugpak SF1 and the SF bivvy bag are more or less a lightweight version of this Carinthia system.

You have to ask yourself honestly if you go for camping above the freezing point in most cases or not.

If you just need a 3 seasons bag, the SF1 and SF bivvy bag are the more compact, lighter and cheaper option.

If you go also for camping in serious winter conditions the combination with the SF2 and adapter is also worth a thought.

But otherwise you should ask yourself if you really need the best of the best or if the sleeping bag that you already own doesn't do the job as well.

And as you can see in this thread here you can buy a new copy of the Carinthia Defence 4 and a new British army bivvy bag for a pretty low price:

Modular British Army Sleep System?

I would like to know who used a current, new issued or new bought British army sleeping bag system. DId it convince you? I have seen that it is sold here new incredibly cheap: https://www.strikeforcesupplies.co.uk/index.php?method=cat&id=6

bushcraftuk.com

The warmer of the two British army bags is surely large enough to put your existing sleeping bag in there if you want to go for serious winter camping.

That's a pretty good low budget option here!

The British army medium weight sleeping bag is a copy of the Carinthia Defence 4 in a slightly lower quality.

 

[Joeking]

That’s a lot of information but I’m struggling to find and answer in there. I think you are saying you use a foam mat outside the bivy and not an inflatable inside, as many others do.

Very much appreciate all the input but I have to question a couple of you points. Having read a lot of mountaineering exploits and been involved with my own fair share, I’ve never heard of anyone zipping sleeping bags into a double to save heat! As you point out, it wouldn’t even work if you did as you wouldn’t be able to pull it in tight round you face’s.

Side zippers are the norm because they are cheaper to make… 1 why would they be significantly cheaper. And 2 I think you hugely underestimate how much money goes into the civil outdoor market!

 

[Erbswurst]

I wrote:
"The closed cell foam mat belongs under the bivvy bag to protect it against little thorns and sharp stones. It also keeps the bivvy bag clean. Dirty equipment doesn't work properly.

Some experienced people who want to use an insulating airmat put it into the bivvy bag to keep it warm. Like that you can perhaps avoid ice in the airmat with good luck.
In my opinion it's a bad compromise and I wouldn't do that. In this case you obviously need to use a tarp over you because you can't roll around anymore."

A smaller airmat would fit into the SF bivvy bag if you choose the right size and only use the SF 1. But I don't recommend that.
I wouldn't line a vapour permeable fabric with a non vapour permeable air mat.

 

[Erbswurst]

Civil clients pay a lot of money for pretty bad equipment. That's right.

What mountaineers do, you better ask in a mountaineering forum. Or you simply write an e-mail to the most famous British mountaineer.

But I can tell you how German soldiers slept during WW2 in Russian winter conditions: Each man in his great coat and a blanket around the legs and the whole group together under the connected tent sheets.

The Russians did it differently: Two soldiers slept under two great coats!

I guess they knew very well what they did.

In the right bottom corner in this link here you can see a Swiss army 8 man sleeping bag. You can scroll through the pages in this corner, by the way.

Schweizer Zelttuch 64

Schweizer Zelttuch 64, die Militärplache, ein ganz edler Stoff.

www.team-pak.ch

 

[Joeking]

I’m not saying huddling together for warmer doesn’t work or that it’s never happened, just that modern alpine sleeping bag are not designed to be used like that for maximum warmth. I think it’s just that side zips lose less heat and in a tent there is little benefit of a central zip.

I hear what you’re saying about the benefits of a central zip while sleeping with no tent. Most civilians (with the exception of this forum) choose to take a tent, hence very few central zip sleeping bags on civilian market.

 

[Joeking]

Some civilian kit is overpriced, all branding and marketing. Other civilian kit is the best there is for it’s intended purpose.

If you want to sleep in a wet field with a rifle next to you ready for a quick exit, military gear is for you.

If you want to push the limits of what you can do getting up a mountain, where every gram counts and sleep in a tent to avoid exposure, top civilian brands are more suited IMO.

My current requirements sit somewhere in between…

 

[Erbswurst]

Yes, of course there is very good civil equipment as well. It's rather rare though. And often enough the same makers develop equipment for both markets.

I doubt that in tents side zipper sleeping bags work better than central zipper sleeping bags, unless you would lie in it like a pharaoh in his sarcophagus.

 

[TLM]

With proper construction there is very little difference warmth wise between center or side zips. I have just now both, the handiest zip I have ever had was ages ago a US down bag with the speed opening zip. I wonder why few military bags have that.

I still think what counts is the actual heat insulating capacity of the bag.

 

[Erbswurst]

What's a speed opening zipp?

 

[TLM]

What's a speed opening zipp?

One pulls it all the way up so that the runner drops off from one side, after that the zip can be "teared" open like a broken one, it always works when in a hurry, no snagging.

 

[Erbswurst]

I understand !

My zippers at the Snugpak SF bags don't work like that. But perhaps they are even better:
You just pull the sides at the top and it opens without any problems. You don't have to touch the zipper sledge.

Otherwise they don't open accidentally.