Woodlife Trails

One of the more difficult decisions when splashing out on kit is deciding on whether you should buy a synthetic or down sleeping bag.

There are literally hundreds of makes and models to choose from but at the end of the day it comes down to the filling. Here you have to be honest with yourself and decide in what circumstances you are going to use the bag.

Synthetic filling will be cheaper; easier to maintain; bulkier and heavier. Down will conversely be more expensive, more compressible and lighter but not so effective if it gets wet. The damp UK woodlands might not be wet enough to cause concern if you use a tarp or tent but you would have to watch out if your bag wasn’t in a waterproof stuff sack or if a sudden downpour left you exposed when sleeping without a bivi bag. You might also consider a waterproof stuff sack, particularly if you strap the bag to the outside of your rucksack. If I were going canoe camping on a regular basis, I probably wouldn’t consider a down bag.

My decision to move from synthetic to down filling was motivated by the need to cut down on bulk and weight. I was reasonably happy with the synthetic filled Nanok -10 bag’s performance but I needed a less bulky winter bag.  It was quite long and wide for me in any case, causing a few cold spots. My other down bag, the  British Army ’58 pattern bag is great, but despite being down, it weights in at nearly 3kgs and is just too heavy.

As I started to look around I realised that I was getting into a technical mine field of “fill-power” and ratings. The simple explanation for the former is the volume that one ounce of goose or duck down (one of the best insulators known to man) fills a container measured in cubic inches. This is known as “fill power”. The higher the number, the better quality of down. Duck down is cheaper than goose down but not so durable.

Good quality down will be around 500 to 600 fill power. A fill power of 600 to 700 is considered excellent. The best fill power available today is 900.

The fill power is also a good indication of how much actual downy feather and quill there is in the down. The higher the number that is given, the more feather and less quill. A lesser number means more quill and less feather. Your bag will be loftier and warmer with a higher fill power.

[Pic - www.facewest.com]

Each manufacturer’s vary in the production of their down. Even a sleeping bag that is tagged “100 percent down” could have up to 15 percent feathers or fibres in it. Regulations state however that any lesser percentage must be given on the label, such as “75/25”. This means that there is 75 percent down, 25 percent feathers.

It’s important to check the loft of a sleeping bag. After shaking it the insulation should stay within the baffles or channels of the outer layer of the bag and distribute evenly. The bag should rise like self-raising flour. It’s also important to store the bag loosely so that the filling doesn’t get squeezed up into one area of the bag and thus lose their insulating properties.

There are a number of ways the quilting or baffles are designed, but generally as long as the filling doesn’t cause cold spots by poor manufacturing or just a single layer of quilting, you should be okay. Probably the most standard shape for sleeping bags is the “Mummy” shape. Have a look at the link below to design your own sleeping bag. It’s good fun and will help you learn about sleeping bag design:

http://www.phdesigns.co.uk/dyosleepingbag/

Moisture may get into the bag by the production of moisture from the body which stays in the bag during sleeping. This is known as a vapour layer.  This can be avoided by sleeping in your base-layer or by using a sleeping bag liner to wick away any moisture. Some of the more expensive bags will have a special fabric layer built in.

The next problem is sorting out ratings. Many manufacturers give ratings as to what they think the most appropriate season to use the bag e.g. 1, 2, 3 or 4 season bags. Some give arbitrary “minimal” temperature ratings. There has been an attempt to regulate the ratings by giving them an EN number. This table doesn’t make things that much easier and it’s still very subjective and used only as a guide:

• Upper Limit – highest temperature at which a standard MAN would have a comfortable nights sleep without sweating.
• Comfort – lowest temperature at which a standard WOMAN would have a comfortable nights sleep, lying on her back and relaxed.
• Lower Limit – lowest temperature at which a standard MAN in a rolled up body posture would have a comfortable nights sleep.
• Extreme – temperature below which a standard WOMAN could expect strong sensation of cold and maybe actual physical injury from cold (e.g. frost bite or hypothermia).

Confused? You bet! Worse than this is that it isn’t a legal requirement to provide this information. Nor is it valid for other parts of the world except Europe. Nor does it take into consideration sleeping mat insulation. Nor does it take into account … well, you know what I mean. The list goes on.

There are a few other things that you have to take into consideration when looking at any sort of sleeping bag:

Heavier people sleep warmer than thinner people
Women sleep colder than men
Younger people sleep warmer than older people
Unfit people will sleep colder than fitter people
If you have the heating on in your house during the summer months then buy a warmer bag
Experienced users can get away with less, as they know the tricks of the trade
Eat well, keep hydrated and warm up before you go to bed.
Generate some heat by physical activity before you turn in.
Don’t forget that the mat you are sleeping on is a very important part of your sleep system (I’ll get onto this in another post).

My advice is to research or ask the manufacturer how they arrived at their ratings. You will then have to guess where you fit into that rating based on who you are (physiologically), what you intend to do, where you intend to camp and when. Not easy but it’s worth spending some time doing this to avoid disappointment. Of course, recommendations from other people feature quite highly on the list.

After this exhaustive process, I decided to look at Alpkit’s range of sleeping bags. In the next mid-week post, I’ll show you why I decided on this Alpkit Skyhigh 800 bag and I’ll show you around it.