HYDRATION SYSTEMS… Everything you ever wanted to know



Being 2% dehydrated, makes you 50% less efficient. That statistic alone is enough to make drinking more important than just quenching thirst.

But let’s not get too over enthusiastic about what we drink from, a throw away old soda bottle will carry water and can be re used – we do not have to have an expensive system, but they do have some advantages.

There are so many different types and designs of items we can carry water in and drink from, that it will be impossible to cover every possibility in this training material, so we will look at what we need to stay alive and leave the rest to you to decide based on personal preference.

There is one undeniable fact about anyone on a walking trip – the amount of liquid you will drink is directly proportionate to how easy it is to access the liquid.

If your water container is tucked away in you backpack and out of easy reach whilst walking, the chances are you will drink less as it requires you to stop to get to the container. If you can drink whilst walking, you will tend to sip all day, and if totalled up you will find you have drunk more. This makes a hydration system better for you.

In Brief if you don’t have time…

  • You will need at least 1 to 2 litres of water carrying capacity but check with your leaders as to how much your particular trip needs you to carry.
  • Water containers should be shatterproof, watertight and clean.
  • Try to have your own system which allows easy access to water even whilst you are walking
  • Whatever system you use, it must be cleaned and disinfected after and before every trip
  • Make sure your system is easy to fill from shallow water.
  • Mould spots that have been scrubbed and disinfected are not a safety problem as these are stains in the container
  • Dehydration is the single biggest cause of loss of efficiency on a trek
  • The choice between a bottle and a tubed system is personal and no one system is always right

The Detail…


Any watertight clean bottle will suffice. Be careful of bottles that are easily crushed or can break into sharp pieces. You want a bottle than can take a bit of a beating.

Some walkers prefer a bottle on a long sling, so they can hang it across their shoulders and have easy access to it. Others find the strap an irritation and put the bottle in a side pocket of their pack that can be reached without taking the pack off.

Bottle types range from an old soda bottle which costs you nothing, to hi-tek bottles with built in filtering and water disinfecting systems which cost a lot of money but may be worth it depending on where you are going.

Size also depends on the easy availability of clean water on your trip. The less water available the more you must carry. In most cases a 2 litre or 2 x 1 litre bottles is fine. However, some trip requires much more. Check with your trip leaders.

Hydration Systems & Bladders

Hydration systems are water containers that have lengths of tubing attached that allow one to put the container in your backpack and run the top around to your mouth allowing you to drink on the go. These tubes come with a bewildering selection of attachments, most of which are not necessary. These include digital flow meters, built in filters, valve protectors and insulated covers for cold weather. Some sort of valve to close the end off is the only necessary part you must have. These valves range from simple ‘bite’ valves which open when bitten gently with your teeth, to push/pull and twist valves. Sometimes these latter valves also have a secondary bite valve.

The common thing about all these categories of hydration systems, is they have a bladder of sorts to hold the water. At the basic end of the market are bladders with a drinking tube and bite valve attached, and that is all. These work fine but need care when placing in the pack to not puncture the bladder.

Higher up the range you will find bladders with protective covers, and then bladders built into their own mini backpack. These latter versions are specifically designed for extreme sports persons that do not also need to carry other gear, and only have the mini hydration pack to carry. For the average hiker / trekker this is not suitable, and a simple bladder is best as it can go into your regular backpack.

At the end of the day, you want something that:

  • Carries sufficient water for your needs
  • Allows easy access to drink whilst on the move
  • Is easy to fill
  • Is easy to clean inside
  • Is resistant to damage

The rest is all up to personal choice.

Cleaning & Storage

No matter what type of system you use, they must be washed out, disinfected and stored dry at the end of each trip. With bladder systems, this is more of a job, as the inside of the bladder, the tubes and valves are generally not easy to clean. Special kits can be bought, but many handy trekkers will find a way to clean the system without extra expense.

If mould or discoloration happens to develop…

  • Use hot water and 2 tablespoons of baking soda or bleach. Mix the solution inside your bladder and hold it up above your head while you pinch the bite valve (with your fingers), allowing the bleached water to run through the tube.  You can also use special bladder cleaning tabs.
  • Let the bladder and cleaning solution sit for about 30 minutes.
  • Wash the bladder with hot water and mild soap. Be sure to completely rinse away any bleach or cleaning solution before using again. You can also use special brushes to scrub your bladder and tube.  Brushes are the best way to ensure you are scrubbing all the areas of the bladder clean.
  • Once the bladder is clean, be sure to air dry the bladder so no moisture is trapped inside, which can cause mould to grow.

The same process can be used for bottles.

If you have spots left from the mould, they will never come all the way out because the bladder is permanently stained, but still safe to use.

Store out of direct sunlight in a cool environment.

Ensuring your water is clean is a topic covered in the H&S section of this course.

CLOTHING… Everything you ever wanted to know

There is a famous saying which goes: “There is no such thing as bad weather, just bad clothing” and out on your trek or hike, this cannot be truer.

The clothing you take on your trip does a lot more than just protect your modesty. It is the barrier between you and the outdoor elements, and unless you work outdoors regularly, the sad fact

 is your body is not used to these elements and will feel stressed by them.

It could be just simple discomfort, but it could also be far more serious. Selecting the right clothing for your trip must be more than just grabbing what’s in your closet or choosing the latest fashion. In this section we will look at the principles of clothing selection and learn to understand what makes up good outdoor clothing.

In this section we are going to look at some of the basic design features of outdoor clothing. It must be remembered that clothing is very much a personal choice and there is seldom a ‘perfect’ garment which suits everyone – hence the large selection available in stores.

We will try to suggest features to look for, but you will need to decide if these are what you like, and if they are appropriate for the types of trip you do. If you have any personal insights or suggestions, we can add in her – feel free to use the quick comments box and let us know.

Base Garments

In the outdoors, this is just a fancy way of referring to your underwear, with a higher price tag. Seriously though, your Base Layer is the layer of clothing closest to you skin which is designed to partially keep you warm, but also to remove moisture from your skin keeping it dry. Modern base layers are made from Synthetics, Silk or Wool, with the synthetics being the most common. We must distinguish between the base layers or ‘thermals’ you buy at an outdoor store from those bought at a standard clothing store. In some cases, they look similar, but proper outdoor thermals are technically far more advanced as well as more expensive. Technical Thermals will be made of a fabric which will remove moisture from your skin, but dry very fast as the material does not absorb and hold moisture, it repels it. This is where the poly-cotton thermals bought in your local store differ. Poly-cotton works great on a winter’s night at home, but out in the outdoors, the cotton will absorb moisture and hold it, keeping you damp. The cotton is ‘brushed’ to give it that nice cosy feel, but it’s still cotton.

A good set of thermals will last a long time if you care for them, so are a good investment. Most decent thermals are also designed so you can walk around in them at the end of the day without embarrassment whilst your other clothing dries.

If you are on a seriously low budget and cannot afford good quality thermals, the high street store variety versions will be better than nothing but carry a few pairs to change into dry ones at night. Another trick if you have nothing else, is to wear ladies’ pantyhose as a base layer. Being totally synthetic they serve the same function and the real thing. For the top half cut out the crotch and toe areas and pull it over your head with your arms through the legs. It does work. Not as well as proper thermals, but if it’s a case of this or nothing…!

Hot Climates

The wearing of a base layer may not always be appropriate. In very hot climates, you may find that the base layers thermal properties will cause you to overheat, and you would do better to leave off the base layer and just wear the mid layer. Even tight-fitting underwear may be unsuitable, especially if it is synthetic and washing is not possible. It would be better to go without and allow as much air circulation as possible. We will discuss mid layers in hot climates in the next section.

So, in summary – the Base layer:

  • Provides the first layer of warmth
  • Removes perspiration from the body keeping the skin dry
  • Should be a material that does not ‘retain’ moisture. (No cotton)
  • Should dry quickly
  • May not be appropriate for hot climates

Mid Layer Garments

Your mid layer is your normal layer of clothing, chosen to suit the environment. Retains heat in cold weather, loses heat in hot weather. No one type suits all situations. In cold climates the mid layer (or thermal layer) is the main layer of clothing designed to conserve heat. Notice it does not create heat, just preserves what your body is producing. If you are not producing body heat, you will not warm up. It does this by trapping the warm air around your body, so you want something that is good at trapping air. Fleece, Down and Wool are great for this. Fleece being cheaper is often the choice now. However, do not be enticed to go for one thick layer however much it looks warm – you want to be able to adjust the efficiency by layering. Layering is discussed in detail in another section. Multiple thin layers, two or three thin fleeces or woollen garments will be more efficient than one thick one.

You want to look for garments that have closures at the wrists and ankles, to assist in trapping air. Some jackets will have a drawstring at waist level and bum level to compartmentalise the jacket trapping warmth.

At the same time, you may want a jacket or trousers that have zips that open up the armpit area and sides of the legs, to be able to vent excess heat without taking the garment off. Double direction (2 way) zips are also desirable, allowing access to the inside without having to open it up completely. Pockets on the outside to store small items are also beneficial.

A tie in point at the wrist to attach you gloves to so they cannot get dropped is great for times you need to remove them.

Look also for garments that have reinforcing at the shoulders, elbows, bum and knee areas. This will protect the garment from wear at these areas.

Hot Climates

In hot climates, the mid layer tends to be different. You obviously do not want to be wearing fleece or any garment which conserves heat, you want to get rid of it. So loose flowing garments with lots of venting (mesh panels or zips that can open) is a must. Garments should cover the whole body to protect from the sun. Leave that off-the-shoulder top and crop tops at home or for wearing around the pool. You want protection from the sun and protection from the abrasive wear of your pack on your skin. Many a trip to hot climates has been ruined by a bad case of sunburn.

The fabric for the mid layers in hot climates should be something that will protect from UV radiation and is cool to wear. Cotton is great here as it absorbs moisture holding it and then as it evaporates it creates a cooling effect. There are synthetic micro fibres on the market which also do this, and they are a really great advancement in clothing technology. The great thing about the micro fibres is that they work in hot and cold climates, so you can use the same garment for both.

On the specialised and personal preference side – some ladies like to walk in long ‘trekking skirts’, especially in warmer climates. These allow plenty of airflow, and in areas with little natural screening such as bush or rocks, they provide modesty when going to the toilet. Some men even swear by them.

So, in summary – the Mid layer:

  • In cold climates traps heat around the body by reducing air circulation.
  • In hot climates, protects from the suns radiation, but allows air to circulate.
  • Is your main clothing layer, so should be chosen to suit the environment and task.
  • Should be designed with the useful features you need: Pockets, closures, 2-way zips, vents etc. as needed or preferred.


Outer Shell Garments

Your outer shell garments are the primary protection against the environment. This could be different on every trip, so think carefully about what will suit the trip best. In all environments it should protect against wind and precipitation (rain, hail, sleet, snow etc.)

Your shell should also be a working tool. Pockets to carry things you may need without stopping to rummage in you pack, protection from thick vegetation and possibly depending on the trip, high visibility or camouflage in the surroundings.

Shell garments ideally should also have zip zips to vent heat from the garment even in rainy weather. This is especially important in hot climates, but you may still want mesh inserts to keep flying things out. Shell trousers should also be able to be vented, and if you may need to change during the day, having ‘boot zips’ allows you to zip open the lower leg to put footwear on or take them off without removing trousers.

Many people find salopettes extremely useful, especially the non-insulated variety. The insulated ski type is fine for cold weather, but in warmer climates they will be too hot so look for a pair that does not have the insulating layer. Salopettes look like dungarees, with a high bum area and bib in front held up by braces. They are very useful as they protect the body higher up then normal trousers, (great in thick vegetation and snow) but allow one to forgo the jacket unless necessary as they keep the lower body and internal organs of the abdomen protected.

In hot climates you may want to in addition to the waterproof wind proof shell, include a breathable flowing shell to help reduce direct sun contact. An oversized long-sleeved cotton shirt is an example. This can be worn over the mid layer and left loose to allow air circulation.

Your shell garments include things like your boots, hats, gloves and scarves.

So, in summary – the Outer Shell layer:

  • Protects from wind and precipitation
  • Provides some extra warmth by trapping air
  • Protects from the suns radiation
  • Protects from the harshness of the physical environment
  • Should have pockets to store small items
  • Should have venting zips to allow excess heat out


Depending on the conditions, you may need all three layers of gloves (base, mid & shell) however this will only be in the most extreme conditions.

In most cases a single Mid layer glove is fine, with possibly an outer waterproof shell. Gloves are available that combine Mid and Shell into one pair, and these are fine so long as you do not need fine dexterity, as they tend to be bulky.

Two thinner pairs are preferable in wet climates as you can wear one pair, whilst drying the other pair inside your jacket.

Lightweight cotton gloves for very hot climates are also useful to prevent sunburn, but also to protect from surfaces which can get very hot. It is quite possible to get a nasty burn from very hot rocks or metal you may touch in desert type environments, so a basic pair of gardening gloves works fine for this.

The same principles of the three layers of base, mid and shell apply, so even if you are only needing one layer, use the principles of fabric selection we discussed before and in the ‘Layering System’ topic.

The choice between gloves or mitts is always one that has as many opinions as there are people on the trip. Essentially mitts have the advantage over gloves in that they conserve heat better as the fingers are next to each other in the mitt. However, they are no good if you need dexterity to cook, tie knots etc. There are gloves with cut off fingers and a mitt section which folds over the bear finger part which tries to resolve this problem, and so long as the temperatures are not so cold that frost nip is a possibility, they work. In very cold conditions it will be better to have normal gloves with an over mitt on top which can be removed for fine tasks.


Again, what you wear on your head will depend on the environment. In hot climates you want something that will keep the sun off. An open or closed topped peak hat is not the answer. You ideally want something with a full brim to keep the sun off the whole head and neck. Something more like a cricket hat, but of course such a wide brim gets in the way of the top of the backpack if you are carrying one. In windy conditions a stiff brim will be needed as the soft brim variety tend to blow about too much. Make sure it has a drawstring under the chin to stop it blowing away, and even then, tie a thin piece of accessory cord to the hat and clip it to your pack just in case. A large scarf used to wrap around the head and neck is very useful as well.

In cold conditions you will want to make sure your headwear is a thermal layer to stop the heat loss from the head which is considerable. Wool or Thinsulate are ideal for this. Have a separate waterproof layer of buy a Thinsulate hat with a waterproof layer as part of the one hat. A good ridged peak to keep rain out the face is needed. Having a second woollen or Thinsulate cap or beanie, is useful for evenings and sleeping.


Socks are again one of those personal preferences and there are many myths abounding about what to wear.

Just like we described in the base/mid layer sections, socks should: wick moisture away from the feet to keep them dry and provide cushioning from the impact of walking all day.

Think of a raw tomato. You can rub it on your hand for quite a while without any damage to the tomatoes skin but soak it in warm water for 10 minutes then on the first rub of its skin, the skin breaks away. This is exactly what is happening when you get blisters. The most important anti blister thing you can do is keep your feet dry. The two-sock principle works in hot and cold climates. The first layer is a very thin synthetic layer designed to wick away the moisture, and the second thicker layer provides cushioning. We discuss foot care in detail in the H&S section of this course. If you already have your boots, and they simply will not fit two pairs of socks, use ladies’ short stockings (Hose). Being extremely thin they will not bulk up the boot space but will still act as the wicking layer for your feet.

Remember that when buying footwear, consider that you will probably have two pairs of socks on, so wear the sock combination you prefer when trying them on in the store.

Avoid socks which have seams especially in either the heel area or front of toes. These ‘lumps’ in the sock cause extra pressure, creating problems. Look for socks which have no seams at all.

In very wet conditions, it is possible to get vapour barrier socks, which are the shell garments of the feet. As these generally are made of a waterproof non-breathable fabric, you will still get condensation build up inside the sock, so it is important to stop every few hours and dry your feet and the vapour barrier socks out.


In the outdoors especially high up, the radiation from the sun is more intense due to a lack of pollution and or less atmospheric air it needs to pass through, so protection for your eyes is critical. Permanent damage can be caused on just a couple of days from exposure to the glare at altitude, on snow, light sand and water reflection. Your eyes only have one layer of defence – your sunglasses.

Those cheap pair you bought at the local supermarket will not provide the protection you need, even if they seem a very dark shade. It is not the darkness of the lenses which protects your eyes, but the amount of radiation and light they cut out.

Sunglasses should, especially at high altitudes and in high glare situations, be UV protected and Polarised.

The UV protection is the first thing to look for. UV protection is rated from 0 – 4, with 4 having the most protection. The best sunglasses will block 100% of UV-A, UV-B and harmful blue light. In high glare like snow-scapes and white sand, a rating of 4 is a must.

Polarising lenses reduce the amount of light they let in. Again, this is not indicated by the darkness of the lenses, but how they filter the visible light. Be careful though with polarising lenses as in some motor vehicles you may find you cannot read the digital instruments. This also happens with some digital equipment that has digital displays as these displays are often polarised themselves and the double polarisation mean you see nothing.

The sunglasses should also be shatterproof. Manufacturers can now make almost indestructible lenses, so make sure they will not break if you accidently sit on them.

Go for wrap around lenses to reduce the amount of glare coming into the eye from the sides. For extreme conditions you may wish to look for goggles that can either fit over your regular sunglasses or are sunglasses in their own right.

Photochromatic lenses which change shade in different light conditions are fine for general use, but in extreme conditions they do not provide enough protection. Have normal sunglasses as well.

Oh – and use a neck retainer. They are no good to you if they get blown away or you drop them off a cliff when looking over the edge.

Anatomy of a Layering System

What is it?

Layering has become the standard for outdoor clothing over the last few years. There is nothing complicated about it, it is simply using a thin layer of garments, as opposed to a few thick layers, with each layer specifically designed to perform in a certain way to allow for changes in conditions.

Let’s say you are on a trek and it is quite cold first thing in the morning, you have on your normal clothes and a thick jacket to keep you warm. Although it is still cold, as you start walking you begin to overheat. By removing your thick jacket, you now find you are too cold again. If you had on a few thin layers you could peel off one at a time till you reached the ideal temperature.

Multiple layers are better at trapping warm air against your skin as well. But layering is not just about lots of layers. It is about what those layers consist of.

In broad terms, the layering system consists of three layers:

  • A Base Layer
  • A Mid or Thermal Layer
  • An Outer or Shell Layer

The Base Layer

This layer is primarily used to keep the skin dry, by wicking (mopping) up the sweat as it forms and repelling it outwards away from the body. Your body heat drives the moisture outwards.

In hot climates you will not want to use this layer as the moisture on the skin acts as a coolant as it evaporates, so you will want moist skin with air blowing over it which evaporates the moisture and causes a cooling effect.

However, in cold climates, you want the base layer to remove the moisture as soon as it forms so as not to cause this cooling effect.

Base layers can be worn alone if the conditions are not too cold and they help protect your other layers from becoming too damp.

A few points about base layers:

  • Typically made from synthetic fibre, merino wool or silk. They need to be made from a fabric which does not ‘hold’ moisture, so cotton for example is a poor base layer.
  • Synthetics and silk are very lightweight and wick moisture very well.
  • They need to be skin tight to work correctly. If they are loose, then they will not be able to wick moisture effectively.

The Mid or Thermal Layer

This is the layer which keeps you warm. It traps air around you so keeping you in a warm air cocoon.  Generally, this is a fleece or wool layer. Two or three thin layers are better than one thick layer so that you can regulate how much you need. The thermal layer is usually not water or wind proof. This is effect is ideal, as it will allow the thermal layer to breath much better than other types of thermal layer which are water or windproof/resistant. Some modern ‘soft shell’ thermal layers are water resistant and windproof, and are great for some situations, but if you must have clothing that can adapt easily to many different conditions, rather go for the basic layer which is not windproof.

A few points about mid layers:

  • Typically made from synthetic fleece, down or wool – also should not ‘hold’ moisture as you want the moisture your base layer has repelled from the body to travel through the mid layer into the air to keep the mid layer dry.
  • Synthetic fabrics also retain a lot of heat even if wet/damp, so are much better than cotton as an example which retains moisture.
  • Down holds moisture so think carefully before deciding on down as a mid-layer if you are going to wet environments.
  • Two or three thin layers are better than one thick layer.

The Outer or Shell Layer

This is the shell which protects you against the wind and rain. It also protects against the hard environment such as plants and abrasion.

Your outer or shell layer should always be fully waterproof and windproof. It also by its nature will provide a trap for the warm air inside the garment.

Something to remember with waterproof garments is that they will stop moisture getting out as well as in, so condensation build up inside can cause discomfort. To combat this, manufacturers have developed waterproof breathable fabrics, (see the special article on these), as well as garments which have zipped openings to ‘vent’ the moist air out of the jacket. It becomes a balancing compromise as to whether the moisture build up is more of a problem then losing heat through the vents, especially in freezing conditions.

A few points about outer layers:

  • Must be fully waterproof and windproof
  • Waterproof breathable fabrics will still sweat inside and are not 100% effective but are much better than non-breathable fabrics.

Does this Apply in Hot Climates?

The principle of layering does generally apply to hot and cold climates, it is just the actual fabrics which change.

In very hot climates you will still find in many places that the nights get cold, so you will need to layer accordingly. The normal synthetic base layer as described before can still be used and it will keep you dry, but you will lose out on the cooling effect of moisture evaporating off the skin.

In hot climates you will want clothing which is loose fitting and allows lots of air to circulate through the layers. You do not want to trap the air like you do in cold temperatures.

Layering still works but change the layers to cottons which retain some of the moisture perspired and as that evaporates creates a cooling action.

The Base Layer

  • Cotton or synthetics are fine. Keep them loose fitting so that air can circulate.
  • Try to stay with light colours that reflect heat. Dark colours absorb heat.

Mid Layer

  • Again, stick to cottons.
  • Loose fitting with long sleeves to protect the arms from direct sunlight.
  • Mid layers with venting mesh panels helps to dissipate body heat.

Shell Layer

  • For wet times, yes it can get wet, the same shell as for cold climates is fine.
  • Additional shells to keep direct sunlight off helps – a simple umbrella.

What Clothing Does This Apply To?

It applies to everything, not just the usual ‘tops & bottoms’, it applies to your hands, feet and head – in cold climates. In hot climates you will adapt the system to allow for free flow of air but reduce as much direct sun contact as possible. Create shade with your layering system but allow airflow. Think of people that live in deserts. They wear long flowing, loose clothing covering their whole body. It keeps the sun off but allows air to circulate.

Waterproof Breathable Fabrics

Waterproof but Breathable garments are often hailed as the best fabrics there are for outdoor clothing. “We can wear them all day in the rain, yet we will stay dry inside”. This is the first myth users will discover when they start using them. Waterproof Breathable Fabrics are one of the most miss-understood bits of gear we use.  This short summary of a highly technical subject will try to assist you to understand them better.

Waterproof Breathable Fabrics (WBF) fall into 2 main categories:

  • COATINGS and

Each of these can be either MICROPOROUS (millions of little holes smaller than a drop of water but larger than a molecule of water vapour) or HYDROPHYLLIC (A totally impervious layer that breathes via ‘osmotic potential’ by chemically attracting and dis-assembling the vapour molecule and then conveying it to the other side – much like the cells in our body do).



Performance of either category is measured in 2 main areas.

Breathability or Moisture Vapour Transmission

Breathability or how much moisture can pass through the fabric, is measured in Grams per square meter in 24 hours (g/m2/24hrs) in standard laboratory conditions. This can change radically from sample to sample.  Fabrics tested van vary from 2000g/m2/24hrs to 8000g/m2/24hrs.

Microporous fabrics gradually become blocked so reducing efficiency with common detergents, dirt, body oils and body salt crystals. Hydrophylics on the other hand don’t suffer from this drawback, but usually have a lower breathability to start with.

How Waterproof is it or the Hydrostatic Head

This is how much water pressure the fabric can withstand before it starts to leak through. For the outdoor market two meters is acceptable, three metres is the standard’ and over five meters is excellent but not necessary.

Most waterproof breathable fabrics are 100% waterproof, and it is the tape sealing and construction of the garment that causes problems with leakage. The act of sewing alone creates holes for water to get through. Seam sealing is a difficult and expensive process and will regularly be the first-place water gets through.

Breathability is not the most important factor to consider as moisture transfer is dependent on saturation levels which are reached easily – even during an easy day stroll in the park – hence the need for pit zips and additional ventilation.  What this means is that if the moisture saturation outside the garment is higher than the level inside – little or no transfer of moisture will occur. (If it’s bucketing down with rain, you will still get condensation build up inside the garment if you are perspiring) This is not the garment ‘leaking’.

Waterproof breathable fabrics work best in dry environments like high altitude areas where the air is very dry.


A semi-liquid coating is applied to the back of a carrier or support fabric. It then bonds to form a layer of about 20-30 microns thick. Many types of coatings are available, and performance can vary from coating to coating. Manufacturer’s battle with applying the coatings – too thin and water gets through, too thick and moisture transfer is reduced. Another problem is some coatings do not adhere properly to the carrier fabric and peel off. Coated fabric technology has improved, and the performance is now nearer to that of membranes and some manufacturers are moving to coated fabrics because the cost of production is cheaper.


Membranes are thin chemical extrusions that resemble ‘cling-wrap’ that are bonded to fabrics that act as carriers and supporters of these delicate membranes.

Membranes, as with coatings present a lot of misinformation and half-truths and Myths. The most common of these is that different testing techniques are used to calculate efficiency rates. Some companies have their own standards and don’t use the common standards. Since the variables are different in each case, confusion is common. So, comparing one efficiency rating with that of another brand may not give an accurate picture – comparing different fabrics from the same brand is fine.

Membranes are bonded to the inside of a carrier fabric. Sometimes a protective layer is then bonded on the other side of the membrane to produce a laminate with the membrane in the middle. This bonding process is referred to as laminating. Laminating is expensive and difficult, one of the reasons why membranes are more expensive than coatings.

The biggest problem of waterproof breathable textiles is getting the coating or membrane to bond successfully with the carrier fabric. The biggest problem facing manufacturers of the garment is getting the seams sealed adequately and the biggest problem facing the retailer is in educating you the consumer about the true pedigree of the product.

The advantages of Hydrophylics are that they don’t suffer from clogging and intra-pore destruction – a fact readily identified by the sailing community.

Bear in mind that as much as 60-80% of the price of high end products is taken up by marketing costs. You are paying for the name, and many lesser known brands are just as good.

This WBF section was adapted from an original article by: Dr Andy Baxter & Dr Stefan Metzker

– Cape Storm Performance Apparel


Special Considerations for Very High Altitude and Extreme Cold

Trekkers considering an adventure in extreme cold (-20 °C) and or and high altitudes (7000m+) might want to think about the following in addition to what has already be covered.

Over dressing is the most common mistake inexperienced people make in extreme conditions.

Mummified in thermals, mid layers, duvet jackets and shell garments they end up in a state of heat exhaustion after only a short while. Cotton clothing and sweating are the two biggest problems. As discussed already cotton absorbs the body’s moisture and when you stop walking, the perspiration that has been absorbed in the cotton freezes, radically reducing the body’s temperature, as heat is drawn away to warm the frozen clothing. When you do start to perspire, stop and remove a layer or two. You want to be in a no perspiration state. When you start to feel cold, stop and put more layers on.

A problem with these conditions is that people tend to wear thick down jackets, which can cause a unique problem. The body’s perspiration is driven outwards, but due to the thickness of the down (or similar fill) the perspiration condenses and freezes before reaching the outside air. This causes a build-up of ice inside the layers of the garment. Having multiple thinner layers allows one to adjust the thickness to get a correct balance of warmth but allowing perspired moisture to escape the garment.

At high altitudes waterproof / breathable laminates become redundant because all the available moisture is frozen anyway, and they can become quite stiff and uncomfortable. Lighter windproof and snow proof nylons make for ideal shells.

Surprisingly for the novice, sunny days on a glacier can be very hot. So, a long-sleeved cotton sweatshirt absorbs sweat and reflects the sun’s radiation.

A number of factors can cause frostbite in these conditions; dehydration, altitude, and cold. Keeping the main body warm is the best way of keeping the extremities warm, as the warm blood will flow to the extremities, but that may not be enough. Mitts, as we discussed in the gloves section, are always warmer than gloves. Do not remove the mitts unless you really must. Learn how to tie knots, put on harnesses and take photographs with them on. A windproof, insulated mitt is ideal. A thin pair of polypropylene gloves will prevent fingers sticking to bare metal when there is no choice and mitts are remove. It is worth insulating any metal equipment you may have to touch with 3 mm foam. The T-bar and handle on your ice axe for examples. Unless you take this precaution, even with a mitt on, heat will be conducted away from the hand to the metal it is holding.

Plastic boots are now normal for cold weather trips. Outers have changed over the years with newer materials less prone to shattering, but the inner boots should be insulated with EVA or Alveolite foam.

Buying separate inner boots allows one to customise your plastic boots, but be careful of bulking up too much that the boot becomes tight fitting. The last thing you want are tight boots as this causes poor circulation and cold feet, which is just as bad as inadequate insulation. In really cold conditions and above 7o00m, insulated gaiters or a full over boot covering the sole of your boot is essential as heat is lost via conduction through to the ground and extra insulation is needed here.

Waterproof vapour barrier non-breathable socks are worn over thin synthetic socks to prevent sweat from reaching the wool socks outer and the inner boots, so keeping those layers dryer (and warmer). Feet are often cold when they are too cramped so the ability to wiggle your toes is essential.

A lot of the body’s heat is lost through the head, making it the fastest way to cool or overheat the body. A thin facemask should be the first layer of protection with a wind proofed fleece Balaclava, and or a waterproof cap. Neoprene facemasks are recommended, as they will not ice-up with frozen breath like fleece will.

Remember that sunny days on snow and glaciers can be extremely hot so prepare for heat as well as cold. If you will be using oxygen, practice your clothing combinations at home first to see what works with the oxygen apparatus.

Select clothing based on the expected environment you are going to. Hot, Cold, Wet etc. Just the clothing out your closet probably will not do an adequate job.

Whatever you take should be easy to maintain. Quick drying, Rugged fabric to resist damage, Non-iron, and preferably colours that do not show the dirt easily. Some fabrics have treatments which help resist the build-up of bacteria, so these are good if you cannot wash frequently.

All clothing should be multi-purpose if possible. Zip off long trousers as an example.

Do not carry a new set of clothing for every day. Depending on the destination you are going to, two sets is usually enough except for underwear and socks which three sets should suffice.

Wash clothing as you go at every opportunity you get.

Multiple thin layers are better than thick garments as it allows you to refine the amount you have on to regulate temperature.

Avoid cottons in wet cold environments. Stick to synthetic fibres which dry quickly and hold heat even when wet.

Your clothing on a trek is NOT a fashion statement – choose items that work for your advantage regardless of what they look like.

Wear any new clothing around town at home before the trip to ensure it does not: chaff, irritate, rub, fits properly, does what its meant to etc. – once on the trail it’s too late.


SLEEPING BAGS… Everything you ever wanted to know

Between you and a good night’s sleep are – howling winds, wheezing team mates, partying trekkers and rock covered tent sites to name a few – the last thing you need is a bad sleeping bag. A warm, well-fitting bag to snuggle into at the end of the day will dramatically increase your chances for a good night’s sleep.

Most people need a good night’s sleep. On the trail, this is particularly important because the body has been working extra hard during the day and needs time to rest and repair itself.

This information is to help you to choose the right sleeping bag for your individual needs.

Ask Yourself These Few Vital Questions…

  1. When will I use this sleeping bag most?
  2. What sort of night temperatures will I be experiencing most of the time?
  3. What do I sleep on?
  4. Will the climate be dry, wet or mixed, most of the time?
  5. Do I need a long or short bag?

When Will I Use My Sleeping Bag Most?

Here are some examples of the sort of questions you should ask yourself, with possible options for type of bag:

  • Am I going overnight camping? – Choose a Synthetic bag
  • Will I mostly use it for sleeping on peoples’ floors after parties and so need to wash it regularly? –  Choose a Synthetic bag
  • Will I be doing a lot of travelling, so bulk and weight is important? – Choose a Down bag
  • Do I regularly go cycle touring? – Choose a Down or Synthetic bag
  • Will I be at high altitudes and very cold conditions? – Choose a Down bag

If necessary, write down where you spend all your trips in one year and see what you are ACTUALLY doing for much of the time.

What Sort Of Temperatures Will I Experience?

Think in terms of the seasons of the year because this is exactly how manufacturers rate their bags.

  • One Season – for summer use with temperatures no lower than + 15°C
  • Two Season – for late Spring, Summer, Early Autumn use with temperatures between +15°C and + 5°C approx.
  • Three Season – for Spring, Summer, Autumn use with temperatures between +5°C and -5°C approx.
  • Four Season – for all year round use, but may be a bit warm for summer! Approximate temperature range is between -5°C and -15°C.
  • Five Season / Expedition – these are bags for extreme cold from -15°C to -20°C and below.

Deciding how warm the bag needs to be is a difficult task, but you know when you normally go out in the year, so select accordingly. Always be conservative and if you are caught between two season ratings always go for the warmer option especially with synthetic fills. Providing the bags have a full-length zip you can always cool yourself down, but it is difficult to make a bag warmer! Females are advised, unless you don’t feel the cold always choose a bag with a season rating one higher than is normal. This is because generally speaking women feel the cold more than men do. This is not sexist, simply learnt from experience!

What Do I Sleep On?

If the answer is not an insulated pad or similar, then be very careful. You get cold from underneath, not from the air temperature around you. Insulation from the ground is essential as sleeping bags offer little insulation underneath you. This is because your body weight crushes the filling and so stops it from ‘lofting’ or puffing up. So always, use some sort of insulating mat. Mats are either open or closed cell foam. The closed cell variety are resistant to compression, absorb very small amounts of water but cannot be reduced in size for packing. Open Cell foam is lighter, needs an airtight cover and tends to be self-inflating, these are heavier than closed cell mats, but are more comfortable, provide better insulation and some will pack down smaller. They are more expensive and if punctured have little insulation value. Conventional blow up air beds are impractical due to size and weight.

Will The Climate Be Dry, Wet Or Mixed?

This question can very quickly make the decision for you. If it is going to be cold and dry use down fills, or if cold and wet use synthetic fills and if the conditions are mixed, also use synthetic fills.

Down collapses when wet and loses all its heat, synthetic fills retain up to 60% even when wet. So, if there is a possibility of the bag getting wet always use synthetic. Unless you are like the mountain extremists who are operating in wet conditions but simply can’t afford the slight increase in bulk and weight of synthetic. Generally, this principle holds true for most non-specialist situations.

Do I Need A Small Or Large Bag?

Don’t get a bag where you only use half the available length because these won’t be as efficient in keeping you warm and you are paying for something you don’t need. The closer the bag fits to your body the warmer it will keep you. So long as it is not tight which crushes the loft. Baggy bags are cold as there is too much dead air, so get into the bag in the shop and check it out. Children can use an adult bag but use a cord to close off the bottom of the bag and tuck it under them for more insulation.

The Technical Stuff

By now you have chosen between down and synthetic fill, selected the right season rating for your use and so all you need is a few more technical details and you are ready to choose.

The Main Features of Sleeping Bags

Hood / Cowl

Hoods are essential in cold climates. They increase the comfort and warmth of the bag! For anything below freezing make sure your bag has one. A cold head can give you headaches and considerable loss of body heat.

Shoulder / Neck Collar

A lot of bags have a fitted collar to prevent hot air escaping. This is not restrictive but nice. Essential for really cold conditions, not necessary if it’s mild. Collars also work well for large people as they stop the bag riding down.


Essential for ventilation if you are using warm bags in warm conditions. In hot conditions completely unzip the bag and lay it over you like a Duvet or just lie on top. Make sure there are adequate baffles that run the entire length to prevent cold air getting in or warm air leaking out. Check the zip thoroughly in the shop before purchase. Always go for two-way zips if you can for greater flexibility. Two-way zips are often referred to a ‘foot friendly’ size as they allow you to unzip the bottom to air your feet.

Foot Box

The foot box is a specially cut and fitted panel in at the end of the bag which allows space for your feet especially in mummy bags. Without this your feet would compress the foot section of the fill reducing loft and making for a cold night.

Shapes or Types of Sleeping Bags

MUMMY: This is the best choice for weight conscious back packers. Mummy bags mirror the shape of your body – wide at the shoulders and tapered at the feet and head – without all that extra fabric causing bulk and weight. Their slim shape also means your body will have less space to heat up on a cold night.

COWL TOP: These can be either rectangular or semi rectangular. They have an integral cowl hood to keep your head warm. Mummy bags all have Cowls. Anyone going into cold weather should have a cowl. A large portion of your heat loss is through your head.

SEMI RECTANGULAR: This is the choice for people who need extra room to move around because these bags are slightly tapered at the foot, not totally form fitting. If it does not have a cowl to keep you head warm keep looking till you find a bag with a cowl.

RECTANGULAR: Rectangular bags give you the option of opening wide to use duvet style on summer nights. But they are not the best choice for trekkers. In cold weather, there is a lot of extra space to heat and all that extra material can be un-wieldy in your pack. Some rectangular bags have opposing zips so two can be zipped together to form a double bag with a close friend.

LINER BAGS: Insulated liner bags can add 70C of warmth to an existing bag, while washable cotton or silk liners will keep your bag clean after weeks on the trail.

BIVY BAG: Bivvies’ are un-insulated shells that minimalist’s use instead of using tents. Some feature mosquito netting over the face, others border on being one-person tents, with arched poles to keep the shell off your face and sleeping bag. Make sure any bivvy bag under consideration has factory sealed seams. Bivvies’ won’t keep you completely dry in serious rain but work fine otherwise.

OVERBAG: Over-bags are the way to go if you need to add up to 70C of warmth to your bag’s comfort range but your mummy fits too snugly to accommodate a liner on the inside.

CHILD’S BAG: A chilly child is the last thing you want, so using an adult sized bag is not the best idea. You can buy a child’s bag slightly too big so they will have room to grow, but don’t give their small bodies too much space to heat. Look for a mini mummy with a hood, and then hand it down when they have outgrown it.

Beware of cheap bags from large non-specialist chain stores – these bags are not suitable for serious walkers and only suit after party sleeping in your friends’ lounge.

Temperature Ratings

While the industry struggles with sleeping bag temperature ratings, we still have to rely on the individual manufacturers to provide their best guess. We all sleep at different temperatures, so manufacturers use their own general standard. The key is to just use the manufacturers labels as a starting point, factoring in the way you tend to sleep: warm or cold. If in doubt, choose conservatively and go with a bag rated 6 to 12 degrees colder than the temps you think you will encounter.

For most three-season use, a -50 bag is a good bet. For strictly summer or tropical use, +50 bags will serve you well. And for winter trips, look for bags that are rated -150 or colder. If you expect to spend lots of nights in a snow cave, then -300 bags are a minimum.

For most conditions, a four-season bag would fit into the following categories:

Synthetic fill:

  • A mummy bag with a minimum of 270g Hollofill per meter square.
  • A rectangular bag with a minimum of 300g per meter square.

Down fill:

  • A super down bag with a minimum of 280g per Meter Square. (+- 950g in whole bag)
  • A pure down bag (minimum of 80 % down cluster) with a minimum of 250g per Meter Square.

70% of the worlds down comes from China, although most of the finest quality down – 700 fill power – comes from Europe and Canada.

Shell Materials & Inner Linings

The sleeping bag shell is your first line of defence against condensation or spilled coffee, but it also needs to let perspiration vapour escape so the insulation material does not become soaked from the inside. Colour too can make a vast difference: darker fabrics dry faster in the sun.

Modern sleeping bags use ultra-light, windproof, filling proof and highly breathable fabrics in both shell and linings. The most common outer fabric cloths are plain weave nylon, Rip stop nylon or light micro fibres like Pertex. Lining fabrics also include Pertex and unlike early nylons, they are not sticky in warmer weather. Cotton and polyester mixes are still used as linings in some bags, and shops also sell removable cotton liners, in case you don’t like the feel of nylon next to the skin. In addition there are a whole range of other bag liners available, including silk, fleece and fibre pile. Whatever you do, always use a liner. If you want the best use silk, if you want warmth use fleece, (equivalent to one extra season) and if weight and drying aren’t a problem buy a cotton liner.

WATER RESISTANT BREATHABLE FABRICS: These water resistant fabrics block the wind and can add a few degrees of warmth to any bag. Micro-fibres and some proprietary fabrics are a bit more breathable so perspiration can pass through.

RIPSTOP NYLON: Rip stop is recognisable by its little checkerboard pattern. These lines of heavier thread make it more durable and abrasion resistant than plain nylons. Although strong and wind resistant for its weight, it is not water-resistant.

NYLON TAFFETA: Nylon taffeta is a flat woven fabric that provides a silky texture, but is not as robust as Rip stop nylon.

POLYESTER TAFFETA: Polyester taffeta stands up to the suns UV rays better than nylon taffeta and absorbs less water.

POLYESTER/COTTON: Bags with these shells may be cheaper, but they will not provide most trekkers with adequate protection. Any bag that contains even a hint of cotton will take forever to dry if it gets wet, even from perspiration, and will freeze up in cold, wet weather.

GORE-TEX: You will not find many Gore-Tex shelled sleeping bags anymore, because Gore has developed Dryloft, which works better with high loft insulation. You will find Gore-Tex in bivvy bags, though.

Inside Your Bag

A short guide to understanding your insulation.

Fill Material

This is the factor that most often causes sleeping bag shoppers concern. Down has a great cuddly feel and is lighter and warmer for the weight than synthetics, but some of the newer synthetics are close to meeting this standard. If you are the type who cannot seem to keep your sleeping bag dry, consider synthetics, as they dry faster and do not lose their insulation when wet. Canyoneerers should always choose a synthetic bag.

Down Filling

Natural insulation comes in the form of down clusters and feathers. Down traps heat very effectively, feathers by contrast are flat in shape and trap very little hot air. You can get either goose or duck down but there is very little difference for downs of equivalent fill power.

Soft down plumes underlies an adult birds’ outer feathers. Most sleeping bag down is a by-product of poultry raised for consumption, although most good manufacturers of quality bags import down specially bred for this purpose. Fill power refers to downs resiliency or loft; 550 fill


down is the basic, good quality variety. Most good quality bags these days have 650 or 750 fill, the fluffiest, lightest down available.

28 grams (one ounce) of down has over two million barbed filaments that interlock to create thousands upon thousands of dead air spaces to trap warmth.


A well-loved down bag will retain its loft up to three times longer than synthetics, but also requires more care, cleaning, and storage. Just don’t let your down bag get wet. They take weeks to dry properly and can cause the down to clump.

Down qualities vary enormously even to the extent that goose or duck down from one supplier is totally different than from another. The important criteria is the filling power of the down – what sort of loft the down gives for a certain weight. Although white down is generally more expensive than grey down it is not necessarily better. Eider down which is without doubt the best fill power down available is a dirty brown colour.

Pure Down and is made up of 85% down cluster and the balance is made up of down fibres. There are no chopped feathers used.

Super Down is a regional brand name for down which is not as good or pure as goose or duck down. It is far cheaper and as such has been made to a price. Some suppliers use a mixture of duck down & crushed feathers. Super Down is made of 55% down cluster and the balance is down fibre. There are no chopped feathers used.

Three quarter down means that the entire feather is used, which includes a portion of down at the end and half down, is similar except that the feather is longer.

Factors that determine the quality of down fill.

  • The first is the ratio of down to feathers. For a sleeping bag to be called a “down” bag, it must contain a minimum of 85% down. Many cheap bags use ‘chopped’ feathers which does not provide good insulation.
  • The second factor is something called “fill power” and is a simple method of measuring how many cubic inches a single ounce of down can occupy. The higher the fill power the higher the quality, the higher it will loft and the longer it will last. This is very important, because if one ounce of down fills 450 cubic inches and another fills 650 cubic inches, then the sleeping bag with the superior fill power will require less down to the fill the same space, as a result the sleeping bag will be lighter for the same warmth. It is this measurement of “quality of down” that can lead to such a difference in the pricing of bags that appear to have the same weight of fill. Bags can have anything between 450 and 800 fill power.

Facts about fill power

  • The higher the fill power the larger the down clusters – Longer lasting
  • The larger the down cluster the higher the quality – Longer lasting and warmer
  • The higher the quality the longer it will retain its loft and firmness – Value for money
  • The larger the down cluster the more mature the bird from which it came – Longer lasting
  • The larger the down cluster the more air it traps – Warmer
  • The larger the down cluster the higher it will loft – Warmer
  • The larger the down cluster the better the insulating power – Warmer
  • The larger the down cluster the lighter the down bag, will be – Less weight

700 fill power down is composed of 90% down clusters and 10% tiny feathers, and comes from 20 to 24 week old birds.

Synthetic Filling

Some synthetic fillings are warmer, some are lighter, some compress more, and some last longer, but all are less expensive than Down. Two main types of synthetic insulation exist; the first is made up of thin strands, or filaments, of polyester fibres, either continuous or chopped, which have one or more holes running through their length like a straw. It is these holes that trap the body’s heat, and the more holes the synthetic filament has, the more heat it will trap and the more effective it will be. The second, more modern approach is to batt (bond) micro fibres closely together, which trap heat between the fibres in much the same way that down does.

Short staple fibres like Lite-loft, Micro-loft and Prima-loft 1 and 2, pack relatively small and light. Polarguard bags made of continuous batts of fibre layered or quilted together, are a bit bulkier, but tend to retain their loft better over time. On the lower end of the performance spectrum are Hollofill and Quallofill bags that are warm enough and less expensive, but will take up more than their share of space in your pack. Pile or fleece bags make great warm weather bags that can also be used to supplement existing bags.

HOLLOFIL: This low priced polyester insulation comes in two variations. Hollofill II and Hollofill 808 which costs less. Both of these fills appear in entry level products.

LAMILITE: Is continuous filament polyester Fiberfil laminated to the outer shell fabric. It’s reasonably warm when wet. The continuous fibres take less layering to stabilise, saving weight and cost. Lamilite is slickened to improve stuffing and draping. The fibre structure resists the damages of wash and dry cycles better than most synthetics.

MICRO-LOFT: DuPont’s short staple polyester fill, made up of micro fine fibres thinner than a human hair. Its loft looks rather flat, but it is water-resistant.

POLARGUARD/POLARGUARD: Polarguard a continuous filament polyester, was one of the first lightweight Fiberfil’s. It’s still one of the longest-lived fills, although bulky to pack. Polarguard HV is a newer version with hollowed out fibres that are ostensibly 25% lighter.

PRIMALOFT: This short staple synthetic insulation is a combination of large and small diameter polyester fibres intermingled to create a down like feel. It has proved remarkably water resistant, making it a strong choice for wet weather trekkers. It doesn’t seem as puffy as other synthetic fills, but will keep you warmer than its loft will indicate.

QUALLOFILL: Even though the strands of this polyester fibrefill are slickened to regain loft quicker and drape around you better, Quallofill short fibres shed a lot faster than several other synthetic fibres. Newer generation products are replacing this material.

THINSULATE LITE LOFT: This premium synthetic fill is comprised of micro fine fibres heat bonded into a fluffy latticework. It is warm, soft and remarkably compressible but heat sensitive, so keep it away from heat.

MIRACLE FIBRE (Microfilament Polyester): These fibres are 1000 times’ smaller diameter than hollow fibre. This means that the fibres behave in a similar fashion to Down, trapping tiny pockets of air between the strands which is easily heated by your body heat, so, insulating you from the cold.

If you use the same sleeping bag more than fifteen nights a year, consider getting a liner. It’s easier to wash and dry than a bag, plus repeated washing shortens a bags lifespan.


Whatever type of filling you choose it needs to be held in place over and around the body. Synthetics are supplied in layers and so are easy to sew up. Either in a single layer (for summer use) or in a double offset layer (for year round use) or in shingles where batts of fibre are sewn to the outer lining and overlaid to eliminate cold spots. This is the most effective but also the most expensive method of construction for synthetic bags. Down is a free moving product, which must be blown into tubes or compartments of material. These tubes are then sewn together forming a series of channels.

It is the sewing of the fill to the outer/inner that poses the most problems for sleeping bag warmth. If the bag is sewn through, that is the three layers simply sewn all the way through, that means the fill is compressed by the sewing and allows the cold through. (In fact it’s allowing the warm air out) An easy trick is to feel the inside and outside stitching and see if they correspond. If they do it’s a problem, but if the stitching is off set, they its better. Most cheap bags are sewn through as this is a fast easy way of construction. Not good for cold climates.

Sleeping like a Log

How you use your sleeping bag affects how warm you will be.

  • Any bag straight out of the stuff bag won’t be as warm as it should be because the insulation is still partially compressed. As soon as you pitch the tent, un-stuff your bag, shake it out and let it regain full loft.
  • A sleeping mattress not only keeps rocks from your back, it keeps you warmer by cutting conductive heat loss underneath your bag. Forget the old five-tube airbed, and opt for a closed cell foam pad or self-inflating foam mattress.
  • “Warm when wet” is a distinctly relative term. Whether it’s filled with down or synthetics, any bag feels dreadful when wet. Keep it in a waterproof stuff sac, even a refuse bag will do. Maintain the outer shells water repellency with periodic spray moisture repellent touch ups. Be careful about keeping wet goods away from your bag.
  • Wet gear should be stored away from your bag. Condensation on tent walls can shower everything inside, so keep a vent open to minimise water build up. Air-dry your bag whenever possible, a sun warmed boulder is an ideal place to drape it.
  • In cold weather always wear a warm hat when sleeping, since much of your body heat escapes from a bare head. Wearing thermal underwear to bed often makes the difference between sleeping and shivering. Don’t overdo the added clothing though. If you overdress, the added bulk can compress the loft in your bag as well as prevent the heat from your body warming up the bag and you will sleep colder.
  • Food is fuel, so eat and drink warm foods before bedtime. The perfect excuse for high kilojoule bedtime snack.
  • Dehydration leaves you cold and listless so keep hydrated. Drink your fill before retiring, drink when you wake at night, and whenever else you can. You will know you are drinking enough when you urinate four or five times a day and it is relatively clear. Yellow urine is a sign of dehydration, unless you are taking vitamin B supplements which stain your urine yellow.
  • Since a bag cannot retain body heat that is not there in the first place. Eat a hot dinner and enjoy a hot drink before retiring. Just don’t go to bed sweaty.
  • Pour hot coffee, chocolate, or tea into you sleeping bag. By this we mean get into your bag then drink that last cup. In this way you are making sure you do not lose that precious heat to the air.

Goose down has essentially the same chemical make up as human hair. 88% protein, 11% nitrogen, 1% miscellaneous chemicals.

The Four Heat Thieves

If you slept through science at school, you will have missed the chapter about how and why you might wake up shivering in the middle of the night.

Here is a look at the mechanisms of heat loss in sleeping bags, and how a good bag prevents heat loss.

CONVECTION: The transfer of heat by moving air; for example, wind blowing through shell materials or zippers, or leaking around hoods. Convective heat loss is prevented by good bag detailing, like a snug hood and tight zipper baffles, windproof shell materials, and contoured mummy cuts.

CONDUCTION: transfer of heat directly through a substance, the way hot coffee in a cup warms your hands. Air is a poor conductor of heat so materials such as down or synthetics that trap lots of dead air (like body heat) in little pockets make the best insulators.

EVAPORATION: The loss of heat through the evaporation of perspiration. Your body loses heat through the night as you perspire normally, and as the sweat transfers into water vapour, large amounts of body heat are lost. Most sleeping bags do little to guard against evaporative heat loss unless they have a vapour barrier liner. (VBL). VBL’s are waterproof inner bag liners that harness the heat generated by the body through evaporation and prevent subsequent heat loss.

RADIATION: The transfer of heat between any two objects in direct line of sight or contact with each other. Stand next to a hot stove and you will feel radiant heat. Radiant heat loss in sleeping bags is solved through efficient insulators and bag construction that prevents cold spots. Some bags have special liners that reflect radiant heat back to your body.

Sleeping Bag Care

Although cleanliness is good, you should wash your bag as little as possible as the washing process reduces its efficiency. It is quite common for regular trekkers to have bags that are ten years old that have never been washed – just well looked after.

  • Do not roll your bag when putting it back in the stuff bag – it’s called a stuff bag for a reason – rolling creates folds at the same point all the time so damaging the fill – stuffing randomly folds the fill so reducing damage.
  • Cleaning any bag does effect performance to some degree
  • Avoid the necessity of cleaning by always using a liner
  • If cleaning always use natural soap products
  • Down is difficult to clean so use a recommended company to clean the bag
  • Always store your bag loose, either hung or rolled up loosely
  • Never store you bag in a compression bag for long periods – this will damage the fill.
  • Air your bag regularly when in use to prevent dampness
  • Always make great effort to keep the bag dry by:
    • Wrapping your bag in a waterproof cover inside your back pack
    • Choose your sleeping surface and location carefully
    • Checking your tent doesn’t leak
    • Not sleeping against the side of the tent or damp hut wall
    • In extreme conditions carrying the sleeping bag wrapped up inside your bivvy bag for full protection

The important lesson is to take precautions to keep you bag dry. Remember, dry bags are safe bags.

Final Bag Selection Checklist

The Basic Standard:

A -5°C bag is suitable for most three season trips. Down is a highly compressible insulation and provides more warmth for its weight than synthetic fills, which are preferable for use in wet conditions. Look for a zipper baffle, a draft collar and a trim fitting design for maximum heat retention. Condensation will dry faster on a dark coloured shell.


Adjust the temperature rating up or down if you are a very cold or warm sleeper, or if your typical trip exposes you to hot desert temperatures or freezing mountain air. Some companies make bags especially shaped for the female form and for children.

BACKPACKS… Everything you ever wanted to know

Backpacks, Rucksacks, Knapsacks, Haversacks, and Kitbags, whatever you call them are the easiest and most comfortable method of carrying  equipment and provisions when you must carry it yourself. The weight is mostly supported by the pelvic girdle with a little by the spine and shoulders, leaving the hands free for doing whatever you need to do with your hands.

Packs are never one size fits all, so try on a few before you decide which one is for you. It may seem like an inconvenience, but bring a bag of gear to the store, load up each of your preferred selection, and walk around for a while, then choose the one that suits you best. It is a bit strange that shops do not have bags of gear specifically designed to simulate the weight of a loaded pack for you to try on in store.


Once again, gear is like underwear – everyone’s tastes are different and there are a lot of grey areas in selecting the best. We have tried to provide the most pertinent advice but if you don’t agree with us share your ideas with us and we will include them in this material.

Let’s get one thing out the way right now – not everything the manufacturers put on a pack is necessarily useful, desirable or even serves a purpose. It is a sad reflection of the marketing world that we buy things because they are fashionable regardless of purpose. An example of this is having Ice axe loops on tiny day packs just big enough for a sandwich. They serve no purpose other than to maybe hang you mug off of, but look the part and so manufacturers add them. Make sure you identify each aspect of your needs and get a pack that meets as many as possible.


Before we look in detail at backpacks, ask yourself…

1. How much gear am I going to have to carry?
2. Do I prefer my gear sorted into compartments?
3. Do I need to be able to flex my torso a lot on the trip I am planning?
4. How easily do I need access to the gear in the bag?
5. Will I be needing to take the pack off and put it back on often?


Backpacks are like handbags – the bigger it is the more you will want to put in it. When selecting a bag, be honest with yourself about how much gear you really need.

The size of your chosen backpack should be related to the activities that you will be doing, bearing in mind that no one bag will be perfect for all your chosen uses.

There are four main size & uses of backpacks, and many varieties of each:

Day Bags

10 – 30 Litres – Day walks from a base.

The simplest form of backpack. Shoulder straps and a pocket of sorts are standard. More expensive versions may have a waist belt for stability, this is not usually padded, nor designed to absorb the weight carried, unlike the padded hip belts on larger backpacks. Some larger day bags may have a padded back for support and comfort.

Soft Packs

25 – 50 Litres – Rock climbing, Supported Treks, Mountain Biking, Skiing, Hill running & Hostelling.

This type of backpack is for those engaged in multi-sport activities. The main difference between this type of backpack and day bags mentioned above is that they are designed to carry heavier loads (10 kg or over) so many have internal frames and better hip belts, spreading the load more effectively between the waist and shoulders. These packs are often close fitting, improving stability and freedom of movement.

Hiking & Expedition Packs

55 – 120 Litres – Multi-day backpacking, Long mountain tours and expeditions. Generally, ladies should not carry more than 65 litres in this category of pack.

The early external frame packs have now almost totally been replaced by the internal-framed backpack. The external frame has been modified to fit inside the back of the backpack so that they lie parallel to the spinal column, so helping transfer most of the weight from the shoulders to the padded hip belt which is sewn directly into the bottom of the backpack. The hip belt transfers the weight to the pelvic girdle and down to the legs. This protects the spinal column and shoulders from damage.

Travel Bags

50 – 80 Litres – Globe-trotting and combination business / leisure trips.

These bags have similar load-bearing systems as the internal framed backpack and can be zipped-away behind a cover sheet. This is to prevent the straps from getting in the way when not required or getting caught in conveyer belts in airports. In addition, the travel bag usually has an unconventional zippered front-loading feature like a suitcase that allows the entire bag to be opened and packed as a conventional suitcase. It has straps and handles that allow it to be carried like a conventional piece of luggage. If cost is a factor, cover bags are available that store a conventional backpack during transit, providing the advantages of the travel bags.


Materials and fabrics match to the intended use of the backpack. A daypack will be made from a lighter material then a larger internal-frame backpack. However, material for the same size of bag will vary according to intended use. For example, a canyoneering bag will be made of robust waterproof PVC, where as a bag for easy day walks will be lightweight rip stop nylon usually.  Similarly, a large backpack will have double, or even triple stitching, as it will hold a heavy load.


Many people are organisation freaks and like to have a compartment for individual items. No problem with this if you do not mind the extra weight it generates. Think about how you like to be organised. Some people like just one or two compartments as well as a few external pockets to put regularly needed items in like water bottles, and others prefer to just have one big compartment and stuff everything in from the top. There is no right answer to this. It depends on your preferences.

Many backpacks have a split compartment two-thirds of the way down to allow access to the bottom contents without having to unpack the entire bag. Optional pockets on the top, front and side of the main compartment allow for separate regularly needed items such as map and compass. However, side pockets can make the bag too wide, restricting arm movement and generally getting in way during activities which involve squeezing through narrow gaps.

Some basic single or double compartment packs have optional add on pockets which can be added or removed depending on the trips needs.

Frame Support Systems – Do I need to be able to flex my torso a lot on the trip I am planning?

Keeping your spine in a splint like frame all day can be very tiring and prevent ducking under low hanging branches or looking up at the vultures flying above you. However, depending on what you need to carry, a ridged frame might be just the thing for you.

The frame support system, sometimes called a frame racking system, is what provides the stability and shape of the backpack.

External Frames:

Traditional external frame packs often get overlooked in favour of newer, internal frame packs. If you take long trips and stick to designated trails, externals can handle big, bulky loads. Externals usually position the weight higher and keep it away from your back so avoiding being poked by that tin of beans, but this higher centre of gravity can throw you off balance.

An external frame is exposed aluminium tubing and typically H shaped, with a stretched mesh back band or foam padding and a load baring hip belt. The pack bag attaches to the frame with straps or clevis pins, and the frame often extends above or below the pack bag, giving you a shelf on which you can tie your sleeping bag, tent, or mattress. Check for headroom, because the high load can get in the way of looking up. They usually have pockets and compartments for separating equipment. Perhaps the best thing about externals is that they usually cost about half as much as comparably sized internals.

Internal Frames:

These are slimmer than externals. Their support comes from aluminium or graphite flat bars mounted inside the backpack, sometimes combined with a hard-plastic frame sheet that protects your back from hard objects you have packed and provides more rigidity. Internal frames hug your back tighter and are lower than externals, offering better balance and the feeling of being ‘one’ with your pack as it moves with you and allows bending of the spine.

The narrower width allows arm movement and it lets you to squeeze between trees, and other obstacles that would stop external frames.

Many internals, depending on how they are packed can make you lean forward when walking. They also require more care in packing because hard items can rub against your back. Internals tend to have fewer compartments, so you need to pack carefully and stay organised. (Try to keep items in small colour coded stuff bags).

Internals definitely tend to, if packed properly, feel more comfortable as they allow flexibility of your spine so your back does not feel so tired.

Types of Internal Back System

There are many internal frame system backpacks on the market and the main difference between the manufacturers is how the load is distributed from the shoulder to the pelvis. Opinion differs about how best for the load to be transferred. Some say the hip belt must be rigidly connected (via a frame) to the internal struts. Others say that the hip belt should be allowed to pivot from a central point as the hips move from left to right when walking and the hip belt must follow, not hinder, this natural movement. Some prefer their back support to be like a sports car seat. Then still others fall somewhere amongst these options. There are also back systems designed specially to fit women, although not all woman like these…

Frameless Backpacks:

These packs are meant for light travel. Some actually have a frame sheet (thin plastic sheet instead of a frame) for extra support, but most only have a simple foam pad. They seldom come with adjustable suspension, so make sure the one you choose fits your torso. Look for well-padded shoulder straps and hip belts, and plenty of compression straps (the straps on the sides of the pack) so you can stabilise smaller loads.

These compression straps are designed to reduce the volume to the pack when it is not full by squeezing the pack which stops it moving around on your back. No, they were not designed to hang gear from, but can double for this purpose.

Loading – How easily do I need access to the gear in the bag?

No matter what type of frame you choose, you will also have to decide between a top loading and panel loading backpack.


Panel Loading:

Travel packs normally are panel loading, the main compartment opens via a large U-shaped zipper, making these packs easy to load and organise. The front panel usually opens like a door, allowing you to see all the contents. Look for panel loaders with big heavy weight zippers and compression straps that can act as a backup if a zipper should blow out.

Split compartment packs that load from the top can have zippered panel loading access to the lower part of the bag.

Top Loading:

For people who like to cram their packs, a top loader is best. You just dump gear down the top of the pack, jump on it, and then dump in some more. Most have a sleeve and draw string closure that allows you to expend the volume of the pack. The top pocket buckles over the whole load, and cinches tight. While top loaders tend to be more durable and weatherproof, you need to be more organised. Top loaders due tend to hold more gear in the same size pack as it is easier to compress gear.

Will I be needing to take the pack off and put it back on often?

This is something often overlooked when selecting a pack. Some packs have such complicated strap systems, that taking it on and off is a hassle. When in the store, put a fully laden pack on and check how easy it is to take off and put on again. Everything from easy adjusting straps to a top centre handle to assist lifting is vital. Small pockets in the hip belt also can carry snacks so avoiding the need to remove the pack often.

Waterproofing Your Backpack

Although backpacks are made from waterproof materials, the seams are not usually sealed. In heavy or prolonged rain, moisture will inevitably seep through seams and zips. The most reliable (and cheapest) method is to wrap everything in plastic bags, making it easier to find specific times. An alternative is to use one large waterproof bag (such as an orange 500-gauge survival bag) to line the entire contents, not so easy if your backpack has two compartments. If this is the case, a backpack cover can be purchased, which has the added benefit of keeping the bag clean and protecting it from being damaged, but make sure it fits snugly as they can act as sails in strong winds.

Caring for your Backpack

Considering the cost, you will want to keep your pack in good shape, so it will last several years. Here are some tips to help keep your pack looking like new even after it has been around the mountain a few times.

  • Pack hard-edged items such as stoves or cookware, so that they don’t rub your back or poke holes.
  • Remove any food packs from your pack and don’t leave any crumbs inside. The odors and tasty bits attract vermin.
  • Clean out your pack after every trip by unzipping all pockets and compartments and shake out the crumbs, dirt, sand and hazardous waste like old trail socks. If the pack is dirty, sponge it off with mild soap and water and dry out of the sun.
  • Stitch any rips and seams that are coming apart with a heavy-duty needle and upholstery thread. Dental floss is great for this. If nylon straps start to fray, melt the edges with a match or lighter.
  • Check annoying squeaks on external frames, try silicone spray where the bag contacts the frame. Replace any worn clevis pins or split rings.
  • Carry a spare clevis pin and a couple of rings if you have an external frame.
  • Store the pack in a cool, airy, dry place to keep it from collecting mildew which can de-laminate the fabrics waterproofing.

Backpack Fitting

To guarantee you get a comfortable pack, know the basics of fitting.

Once you have settled on the size, style, and model pack that suits your needs, load it up. At a minimum, you need 8 – 10kg to get a pack to hang correctly on you back. Do this after adjusting the frame. Remember the store may not want you bending all their nice new frames, so you may have to fit the pack properly later. See next section for how to fit the pack properly.

Many smaller packs are not adjustable – if you are thinking of getting one of these, you will need to try on many packs till you find one that fits your torso correctly. The fundamentals you are looking for in a pack are:

  • Weight sits on the pelvic girdle, not the shoulders. About a 70/30% combination is right.
  • Pack sits firm on your back and does not wobble about.
  • Shoulder straps extend lower than your armpits.

Fitting an Internal Frame Backpack

Fitting a bag is a bit of a science, and a good retailer will have a trained pack fitter to make sure you pack fits before you leave the shop. But this is a rarity.

The following is a general procedure to follow to fit your new internal frame pack. You may need to adapt this to your own style of pack. Generally, it is easier to have someone assist with fitting your pack. It can be done alone, but it’s not easy.

  • Your height has little to do with pack fitting. You need to consider the part of your body that wears the pack, your torso & you cannot judge torso length by looking. To find your torso length, get your assistant and a soft tape measure, measure from the seventh vertebra – the knobbly one that protrudes from the base of your neck, down the spine, following all the contours to the invisible line drawn between the iliac crests of your pelvic girdle. As a general guide, if your torso measures less than 46cm, you’re a size small, 46cm to 51cm is a medium and over 51 cm is a large. Most modern packs have an adjustable support system so this largely becomes redundant.
  • Start off with the pack empty and all the straps loose. Put the pack on and tighten the hip belt so that the iliac crest (pointy bit) of your pelvic girdle is one third from the bottom of the hip belt, with two thirds of the belts width above the iliac crest.
  • Ask your assistant to look at your back from the side and gently shape the frame of the pack to bend following the curve of your small of the back. Then shape the top part of the frame to curve around the shoulder blades. You want the frame to be the same shape as your pack, not flat and ridged like when you left the shop.
  • Now gently tighten the shoulder straps, so there is no looseness, but they are not tight either. The shoulder straps should be anchored to the pack just below the crest of your shoulders, providing sufficient wrap without any gaps. When cinched tight, the bottom of the padded section of the straps should extend to a point about a hands width below your armpit. If the strap maxes out all the way to the buckle, then you need a smaller harness. If the buckles are clearly visible when you look front on into a mirror, then the harness is probably too small. The straps should match the contour of your shoulders. If they are too wide, the padding will pinch into your armpits.
  • If your pack has ‘load lifters’ (the small straps attached to the top of the pack and the top of the shoulder straps, gently tighten these so there is no slack, but they are not tight. Again, get your assistant to look at the position of the buckle attaching the shoulder straps to the backpack frame (somewhere between your shoulder blades), and adjust this so that the shoulder straps are about 2 centimetres off your shoulders. The load lifter straps attach to the main pack about ear level, creating a 45degree angle from the pack to the shoulders. If they are not set high enough, you won’t be able to shift the weight off your shoulders.
  • Now remove the pack and put some load in it. About 8 – 10kg should be fine.
  • Put the pack back on after loosening the straps again. Start by tightening the hip belt, then tighten the shoulder straps and lastly the load lifter straps. The load lifters should gently lift the shoulder straps off the shoulders so that your assistant can slide a finger between the strap and the shoulder top. The weight should be being carried on the hips, not the shoulders. You may need to play with the load lifters moving where they attach to the shoulder straps forward or backward to get the right angle to lift the weight off the shoulders.
  • The sternum (chest) strap should be set a few centimetres below your collarbone. Most adjust up and down for fine-tuning especially for the ladies’ comfort.
  • Check the headroom. You want to be able to look up without your head hitting the pack.
  • Lastly if you pack has them, adjust the hip belt width adjusters, (straps on each side of the hip belt), to get the hip belt the same width as your hips.

From the above sequence you will see a pack is fitted to a person. Generally, it is not good to loan your fitted pack to someone else as it will change the shape of the support system so making your next trip uncomfortable unless you re fit your pack.

The aim of an internal-frame backpack is to transfer weight to the pelvis and hips, so the first feature that must be fitted correctly if the hip belt. If this isn’t sitting on the hips, then no weight will be transferred.

Internal frame packs are like underwear, Personal. If you lend it to your friends the frame will change shape to their torso and you will feel uncomfortable on your next trip. So, if you have a super comfy pack, keep it that way by not lending it out.

Loading Your Pack

If you are feeling lopsided or you are going to fall on your face or end up like a capsized turtle, then your pack needs re adjustment.

There are as many ways of packing a backpack. As a rule, people tend to pack the heavy times at the top of the backpack nearest the back. It is worth taking the time to pack your bag in different ways to find out what works best for you. Whatever order you decide on, the principal of “first in, last out” always applies and is worth bearing in mind.

Looking at different frame styles and packing…

External Frame Packs:

Heaviest gear goes on top to get it as far forward as possible. Carry weight too low or too far back and you will have to lean too far forward to counter balance it all, which may turn you into a hunchback…

Heavy stuff – stove, cookware, bulk foods etc. Goes in the upper compartment and topside pockets. Keep heavy items close to your back. Store fuel bottles and water bottles upright in separate pockets away from food and clothing. The tent, usually the heaviest item, is tied on top behind the extender bar. Odd shaped gear fits under the top lid.

Mid-weight gear fills the middle of the pack. Clothing, personal gear, headlamp and the like in the centre compartment and lower side pockets. Stuff spare clothing in plastic bags to protect from rain.

Light bulky equipment goes towards the bottom of the pack. Lash sleeping bag below the main bag. If your sleeping bag stuff bag is not waterproof, line it with a plastic bag.

Tie long items like poles to the frame uprights on each side.

Internal Frame Packs:

For internal frame packs the load creates part of its stabilising structure. Filled the pack stands upright, but with its contents removed, it collapses.

Merely filling the pack however isn’t enough. You need to think carefully about the order in which your gear nestles in the pack. For level hiking over easy terrain, try to create a high centre of gravity. Place loose clothing and other high bulk low weight items low in the pack bag, gradually adding heavier, denser items on top.

For more active pursuits like bush whacking or rough ground, keep the heavy stuff lower and closer to your back to maintain a compact centre of gravity.

Try to pack soft items against your back. Many people with internal frame split compartment packs fill the bottom compartment with heir sleeping bag. This stabilises the pack creating a solid base to build everything else onto.

Tips and Hints

  • Choose a backpack that best fits your main activities.
  • Ask for a heavy weight to put inside the backpack when trying it on.
  • Do not pack the heaviest items in the bottom of the backpack.
  • When fitting a backpack, fit the hip belt first.
  • Experiment by loosening or tightening suspension straps to see what difference they make.
  • Buy the bag which feels the most comfortable not with the prettiest colours or pockets.
  • Waterproof your backpack with plastic bags, or use a backpack cover

Selecting Your Backpack Checklist

Be honest: Choose a pack that serves your actual needs not your pocket or ego.

The Standard:

An internal frame pack with 65 to 90 Litres of capacity offers good versatility for most people. Make sure the torso fits, then look for a firm hip belt, curved shoulder straps that end just below your armpits, and enough clearance for your elbows and thighs.


Do you want pockets or a hydration system-ready pouch? These and other decisions about features will help you design the perfect pack. Women may want to try out frames, harnesses, and hip belts designed specifically for female hips and torsos.

In Summary

  • Get a pack that suits the trip you are doing – forget fashion or cost considerations.
  • Internal frame packs should ideally only be used by one person.
  • 50 – 75 litres are more than big enough for the average trek. Only go bigger for fully self-contained unsupported trips.
  • Internal frames are better if you need a lot of movement such as bending under obstacles or twisting through narrow spaces.
  • No pack is waterproof unless specifically designed for water based activities.
  • Packs directly off the shelf need to be fitted before they will be properly comfortable.
  • If you pack hurts you, it is either the wrong type of pack or has not been properly fitted.
  • Most of the packs weight should be carried on the pelvic girdle – not the shoulders.
  • In wet climates – always waterproof everything in the bag.
  • Always empty out the bag and air at the end of a trip.
  • Generally, keep heavier items near the top of the pack.