With the exception of the frozen deserts in the Arctic and Antarctica, most of the world's deserts lie in two belts within 25 degrees of the equator. These belts are considered to be deserts because the high atmospheric pressure causes dry, cold air from the upper altitudes to compress and come down to earth. This dry air is so clear that it can be easily heated by the sun, causing high ground temperatures with very low humidity.
The Sahara (the world's largest and hottest desert, with temperatures reaching 57.6°C (136°F) and the Atacama (the world's driest desert) on the coast of Chile and the Kalahari in Africa were formed in this way. The Gobi Desert is a cold winter desert and daytime temperatures can drop to -30°C (22°F). In all deserts, including subtropical desert, which is very hot in the daytime, the temperature can get very cold at night.
Desert found between two mountain ranges, one on the east and one on the west of a land expanse, which block moist ocean air from reaching the land, is known as a 'rain shadow' desert. Almost all the precipitation falls on the opposite side of each mountain range leaving the region between the mountains dry. Very few deserts are formed solely by a rain shadow effect because they are also influenced by the high atmospheric pressure. The Atacama Desert is a true rain shadow desert and is one of the driest places on Earth. It is virtually sterile (not even bacteria can live there) because it is blocked from moisture on both sides by the Andes mountains and by the Chilean Coast Range.
Where the climate is so cold that the air can only hold a small amount of moisture and there is very little precipitation, all the surface water is locked in unusable blocks of ice. These conditions have created the Antarctic and Arctic deserts.
Most deserts have a 'rainy season,' but this can be as short as a few days of rain in several years, or it can mean several days of rain in one year. All deserts have one thing in common, in the rainy season, the desert blooms. Desert plants, seeds, tubers and bulbs are adapted to lying dormant for extended periods waiting for rain. When the rain comes, they rapidly grow. The effects of climate change on deserts is not currently obvious, satellite images from the last 15 years do seem to show a recovery of vegetation in the Southern Sahara and in other deserts there seems to be more than average rainfall, but the phenomena is too new for one to state that the world's deserts are retreating because of climate change.Dangers
Very few desert animals can kill a human being, however, there are venomous snakes, scorpions and spiders, which in a serious survival situation could be a fatal encounter if there is no chance of medical assistance.A bit about snakes
There are many species of venomous snakes in the world's deserts, although there are no venomous lizards outside of North and Central America. Snakes found in or near salty water that have a laterally flattened tail are sea snakes; all are venomous, many highly venomous. Venoms are neurotoxins. Land snakes, whose heads are triangular and wider than the neck, with eyes that have vertical (cat like) pupils are vipers; all are dangerously venomous regardless of size. Photo, above, is Saw-scaled viper (Echis carinatus). (Though it rarely grows to even 24 inches in length, this is a highly venomous species responsible for numerous human deaths each year.
Because of its fatality rate, this species is listed as one of the most dangerous snakes in the world. The venom is composed of almost equally neurotoxic and haemotoxic components. Bite victims typically manifest widespread haemorrhaging and respiratory failure. The vipers are active by day and travel over sand in a sidewinder fashion. When cornered, they inflate the body and rub sections against each other, producing a loud and ominous hissing sound. They strike quickly and repeatedly.)
Sand boas resemble vipers, but their heads are not triangular or wider than the neck. Primary venom component is haemotoxic (enzymes digest circulatory vessels). Snakes with heads only slightly broader than the neck, with large scales on top of the head and smooth scales, are cobras. Not all cobras will extend the hood if annoyed. Cobras are largely black or brown, shiny snakes. The venom is highly dangerous and neurotoxic.
All snakes give warning before attacking; respect the signs. Most snakes will flee from you and only attack if you surprise them or corner them. A snake can strike from a distance of half its body length. In a survival situation, with no medical assistance, all snakebites are potentially life threatening.A bit about scorpions
There are over a thousand known species of scorpions and most of these inflict a painful sting. Only a few have venom deadly to humans, so you would be very unlucky to be envenomated by one that could kill you. The Fattail Scorpion and the Palestine Yellow Scorpion are among the few really deadly species. (The Fattail scorpion or fat-tailed scorpion is the common name given to scorpions of the genus Androctonus, which are the most dangerous in the world. They are found throughout the semi-arid and arid regions of the Middle-East and Africa. They are a moderate sized scorpion, attaining lengths of 10 cm (just under 4 in). Their name is derived from their distinctly fat metasoma, or tail. Their venom contains powerful neurotoxins and is especially potent. Stings from Androctonus species are known to cause several human deaths each year. An anti-venom is available.)Photo left: Palestine Yellow Scorpion, Leiurus quinquestriatus is extremely rare but one of the world's deadliest. Photo right: Arabian fat-tailed scorpion, Androctonus crassicauda. Without antivenin the victim will probably die.
(You are more likely to be stung by a scorpion than bitten by a snake or spider. Sensible precautions include always shaking out footwear before putting it on and not picking up equipment like a backpack without first turning it over and inspecting it. If you have to sleep on the ground, spread hot ashes from a fire over the area to deter scorpions and other creatures. Never handle a scorpion. To kill one for food, first pin down its tail with a stick, cut off the stinger and claws. The scorpion can be eaten as is - it tastes like an explosion of puss in the mouth but it is all protein.)A bit about spiders
Desert spiders will not normally bite you unless you come into contact with them accidentally. Most spider bites are not fatal but can make you feel ill. If in a depleted state, the victim may be very weakened by the toxin. For example, the female Black Widow
Spider, although it is the most venomous spider in North America (and can be found in many American deserts), seldom causes death as it injects a very small amount of venom when it bites. Reports indicate human mortality is less than 1% from Black Widow Spider bites and no one has died from a bite in the USA in the last 10 years.
The "Camel Spider" is a common name for solpugids, large (non spider) arachnids found in desert regions. They do not bite humans and even if they did, their bite would not be dangerous. The Australian, Red Back Spider (photo, right) generally doesn't leave or wander away from its web. Most bites occur when the victim inadvertently places a hand onto the web. The fangs of the female have the potential to penetrate human skin causing toxic neurological reactions. Due to the small fang length, most bites aren't sufficiently deep to cause problems and since the introduction of antivenin there have been no recorded fatalities. The males are even smaller and generally are much less dangerous; they are regarded as non-venomous.Quicksand
Quicksand is not a special type of sand, just sand that has been liquefied by a saturation of water. The "quick," refers to how easily the sand shifts when in this semi-liquid state. Quicksand is caused by flowing underground water saturating an area of loose sand when the water trapped in a section of sand can't escape. (Theoretically, quicksand can also be caused by air being trapped in the sand, forming a fragile pit of sand and air, but this has never been recorded outside of laboratory experiments.) Quicksand is more inconvenient than dangerous and it is easier to escape from it than you might think. The human body has a density of 1 g/cm3 (62.4 pounds per cubic foot) and is able to float on water. Quicksand has a density of about 2 g/cm3 (125 pounds per cubic foot), which means you can float more easily on quicksand than on water, although the sand to water ratio of quicksand can vary, causing some quicksand to be less buoyant.
The key is to not panic. Most people who drown in quicksand (or in water) are usually those who panic and begin flailing their arms and legs around, causing them to sink. Your survival depends entirely on the depth of the quicksand and if there is anyone around to help you. If you were in above your knees, it would be very difficult to move, a bit like being planted in wet cement. If you were in up to your waist, it would be extremely difficult to extract yourself from the dense slurry.
If you try wading in quicksand, you have the added problem of working against the vacuum caused by your movement. The best chance of survival takes some courage because to escape you have to lie back and let your legs float back up to the surface. Once you are floating, you can slowly paddle yourself to firm ground using just hand movements, keeping your legs together. Scary, but not life threatening.
It is impossible to remove a vehicle from quicksand if the driving wheels are bogged down without the help of a powerful winch and a ground anchor.Sand (dust) storms
If you are in the desert for any length of time, you will almost certainly encounter a sandstorm. The ferocity of a sandstorm depends on the force of the wind and a sandstorm can range from mildly annoying to a serious threat. A turbulent, suffocating cloud of particulates reduces visibility to almost zero in a matter of seconds. A violent sandstorm can carry with it larger particles, even small stones and these can cause serious injury.
Nearly all dust storms are capable of causing property damage, injuries and deaths. They are most commonly associated with the Sahara and Gobi desert regions but they can occur in any arid or semi-arid climate. Storms vary in both size and duration. Most are quite small and last only a few minutes, while the largest can extend hundreds of miles, tower more than a mile into the sky and last for many days. Sandstorm conditions are also ideal for thunderstorms and lightning often accompanies a sandstorm.
A sandstorm can give a total blackout, so you must not move and if you are with a group, it is best to hold hands or lock arms. If a person has to leave the group, for example during a military operation, the person leaving should be secured by a rope to a member of the group so he/she can find their way back. If you have a camel, sit to the leeward side of it (camels can survive sandstorms). If you have a vehicle, close all doors, windows and shut off outside vents; do not turn on the windscreen wipers as the sand will damage the windscreen and you will probably burn out the windscreen motor.
If you are caught on foot in the open, try to take cover behind a rock or other landform to get as much protection as possible. If you are on a sand-dune, do not shelter on the leeward side, although this might seem the obvious thing to do, the force of the wind will move huge amounts of sand quickly and you could easily be buried. There will be a huge amount of surface sand shifting in the storm and the driven sand will also bounce off the surface, so being close to the surface is the worse place to be.
Never lay face down, as you risk being injured or buried. If you have time to head for high ground, it is best not to shelter on the highest point (even though the wind blown sand has less density on high ground), as you risk injury from larger flying objects and if there is lightning, from being struck. Do not lie in a dried river bed or ditch because there may be flash flooding, even if there is no accompanying rain, it may be raining elsewhere.
Once engulfed by a sandstorm, the temperature will rise and there will be significantly less available oxygen, so it is a choking, suffocating and blinding experience. To survive it, you should always cover your head and as much exposed skin as possible.
Swallowing sand particles is unpleasant but not a serious health threat. Getting dust and sand particles in the lungs is a health risk. The force of a sandstorm can be equivalent to sandblasting paint off a car. As soon as a sandstorm begins, sit with your back to it, cover up and protect your head with whatever you have available, such as a backpack. If you have petroleum jelly, apply it to the insides of your nostrils, lips and ears to help prevent the mucous membranes from drying out. Moisten the covering around your nose and mouth to trap smaller dust particles that could otherwise choke you if you can spare the water. If you have airtight goggles, wear them and keep them on long after the storm has abated as small particles may still be flying around.
At night, in winter and in cold deserts, it is still possible to experience a sandstorm. The freezing winds of a winter dust storm can quickly lead to hypothermia, so it is important to put on as much warm clothing as you can. If you are with a group, huddle together to conserve body heat.Flash flooding
It is rather a surprising statistic that more people are killed by flash flooding in the desert than heat exhaustion or dehydration; the photo above shows a flash flood starting in the Gobi Desert. Flash flooding is a surge of water through a valley, canyon, wash or dry river bed. (Washes are also known as arroyos in the USA.) They generally originate up in the nearby mountain ranges and act as a funnel, draining storm water off the mountainsides. Because washes contain water at some time during the year, you will find plants that need more water growing along the edges of them. You can often pick out a wash from the surrounding landscape because it looks like a green ribbon standing out from the dusty tones of the surrounding desert. You should look out for this landmark if you are searching for water.
Desert areas are very susceptible to flooding because the hard, dry desert soil doesn't allow rains to soak in before the water moves across the dry ground. The reason people are caught out by these floods in the desert is because there may be no rainfall apparently in the area. The flood may be caused by torrential rain miles away, often originating in a mountainous area. The lack of regular rain to clear water channels may cause flash floods in deserts to be headed by large amounts of debris, such as rocks, branches and logs.Human survival
An average, fit, healthy person exposed fully to the desert sun will not last the day without water. However, survival in the desert is possible and many people unused to this harsh environment have survived to tell the tale. The desert may look formidable, but many people live in and around desert areas, as do faunae and florae. You can survive in the desert too; you just have to know how to do it.
These days, most people end up in a survival situation in the desert because they wandered into it (on foot or in a vehicle) without understanding how quickly things can change or go wrong; not realising just how quickly one can get hopelessly lost. This applies to both the military and to civilians. These are the basic rules of survival in the desert:
- You need to conserve water. Breath through your nose to conserve moisture, do not smoke or consume alcohol as this will dehydrate you more rapidly. If you have food, but no water, only eat tiny quantities or you will dehydrate faster. Finding water is priority one.
- Do not drink your urine, as this will make you thirstier and rapidly cause liver failure. (For the sake of accuracy I have added this comment: There is a method for drinking urine in a critical situation when there is absolutely no other liquid available. Do not collect the first two decilitres of the urine you pass as this contains the highest concentration of impurities, collect the rest. Drink it straight away and do not store any.
Bear in mind, unless you can re-hydrate with water before collecting further urine, each time you collect and drink it the impurity level will build up dramatically and rapidly lead to the failure of your liver and kidneys. Note: You will die from this anyway, so if you have absolutely no chance of rescue and zero chance of finding water, drinking your urine will not prolong your life for more than a few hours and your death will be more painful and unpleasant than lying down and dying of dehydration. It is a call only you can make!
The best use of urine is to wet your headdress with it to benefit from the cooling effect of evaporation. Another argument for not drinking you urine is that very likely you will vomit weakening you further.)
- You need to keep out of the daytime sun and only move at night. If you have a vehicle, use it for shade. Remember, all metal parts will heat up in the sun and burn flesh if you touch them.
- Stay where you are if you have a good chance of being rescued. Wandering only a short distance from your crashed plane, stranded vehicle or from the party you were with, can be a disaster. A person can rapidly get lost and rescuers may not be able to find him/her in time. If you do decide to move, mark your direction, so potential rescuers know where you are headed.
Even though you may be leaving a clear track with your footsteps, a small breeze can obliterate these in seconds, so do not be fooled into thinking potential rescuers will necessarily be able to follow your tracks. Disorientation can set in rapidly and if you do not have a compass, you will definitely end up wandering around in circles.
- All deserts are hotter in the daytime and you should not exert yourself while the sun is up. As the air heats up, it will slowly cook you, so all you can do is try to find some shade behind rocks, in caves or near water. Rest throughout the day and walk at night. Try to reduce sweating, as this is water loss. Wear white or light coloured clothing to reflect as much of the sun's rays off your body as possible.
Covering the head and back of the neck is critical to keep the brain cool. If you can wet your head covering to increase the cooling effect, this helps. If you cannot spare water for this, use urine. The ground in the desert is hot in the daytime and raising yourself even a few centimetres off the ground will have a significant cooling effect. If you cannot find any shade or raise yourself off the surface, dig away the surface sand, as the sand below the surface is cooler and even a few degrees reduction in surface temperature can help survival.
- Do not climb or drive up sand-dunes if you can avoid it. Dunes are often fragile and unstable and you may end up being buried in an avalanche of sand. Climbing dunes uses significant amounts of energy and you will perspire and lose precious water. The area near the base of sand-dunes can turn into quicksand if it has rained.
- Be extra cautious if you are in the area of a wash, down in a canyon or near a dry river bed because all these areas are liable to flash flood. These floods can strike with very little warning and the water can have terrific force.
The Bedouin of Egypt, who regularly cross 2400 kilometres (1500 miles) of almost sterile and uninhabited desert in all seasons, reckon on 5 litres (1.3 US gallons) of water per person per day, including water for drinking and cooking, but not washing. This allows a reasonable margin for emergencies and unexpected rises in temperature. In the hot season the daily requirement goes up to 10 - 15 litres (2.6 - 4 US gallons) of water per person per day. If you are in the shade during daytime, or in a vehicle most of the time, a person can manage on 3.8 litres (1 US gallon) of water per person per day.
You should drink even if you don't feel thirsty because thirst is a late warning of dehydration. If you have food and little or no water, do not eat, as this will dehydrate you faster. Smoking also speeds up dehydration and drinking alcohol is a "no-go," as this will dehydrate you faster still. If you have a limited supply of water, drink as much as possible because this is the one situation where rationing water will not save you. Drink while you can and when you can. Illness
Chronic bacterial infections are a risk, mainly from certain uncommon mycoplasmas, such as Mycoplasma fermentans (known as Chronic Fatigue Syndrome or Fibromyalgia Syndrome); this is treatable with antibiotics. Micro-organism infections are possible, such as those caused by the Brucella species, Y. pestis, or other bacteria. Most desert illnesses are caused by excessive exposure to sun and heat. Heat exhaustion is the result of dehydration due to intense sweating. It is possible to lose one or two litres of water per hour in extreme heat. Symptoms are a pale face, nausea, cool and moist skin, headache and cramps. To treat this condition, drink water, eat high-energy foods, rest in the shade and cool the body anyway you can.
Early symptoms of heatstroke include unusual or illogical behaviour, elevated temperature, flushed appearance and a weak, rapid pulse. The condition can rapidly progress to unconsciousness, seizures and death. A heatstroke victim must be cooled immediately. Continuously pour water on the victim's head and torso, fan to create an evaporative cooling effect, move the victim to shade and remove excessive clothing. If you cannot do this, the heatstroke will soon become severe.
Severe heatstroke victims needs evacuation to a hospital, so it best to avoid heatstroke by always covering your head and neck, preferably with dampened material and by keeping out of the direct sun. Hypothermia can also develop, particularly if the person is fatigued. While hypothermia is most often a concern during the winter season in cold deserts, it can occur at almost any time of year at higher elevations especially if travelling at night. Night-time temperatures can drop below 10°C (50°F) even in summer.
The risk of hypothermia is greater in windy and or wet conditions. Symptoms include uncontrollable shivering, poor muscle control and careless or illogical behaviour. To prevent hypothermia, wear wind and water resistant outer clothing and synthetics capable of wicking moisture away from your skin. It is important to eat high-energy foods and drink warm fluids to increase your body's resistance to the effects of cool temperatures.
Constipation and pain in passing urine are common and salt-deficiency can lead to cramps. Continued heavy sweating of the body, coupled with rubbing by clothing, can produce blockages in the sweat glands and an uncomfortable skin irritation known as "prickly heat". Heat cramps, leading to heat exhaustion, heatstroke and serious sunburn are all dangers. A gradual increase in activity and daily exposure to the sun will build up a defence -- provided that plenty of drinking water is available. Various micro-organisms attack the moist areas of the body, such as, the armpits, groin and between the toes. Prevention being the best cure - keep these body areas clean and dry.
Even the most trivial wound is likely to become infected if not dealt with straight away. Thorns are easily picked up and should be pulled out as soon as possible. Where the skin of the feet is broken (for example, from a burst blister), a large and painful sore may develop making walking difficult. Disinfect and cover all cuts with clean dressings and tend all wounds, even minor ones, daily.
Water intoxication (hyponatremia) is an illness that mimics the early symptoms of heat exhaustion, except that urination is more frequent with a higher volume than normal or clear urine. If left untreated, advanced symptoms include behavioural changes, diarrhoea and unconsciousness; these symptoms often require hospitalization. Water intoxication can occur when a person drinks excessive amounts of water and eats very little or not at all, creating an electrolyte imbalance. To prevent and treat early stages of water intoxication, balance your increased water intake with food. When planning a desert expedition, consider packing one of the many electrolyte drink mixes to supplement your water supply.
Sunburn is a serious risk, particularly to the cheeks, nose and lips. Use a high factor sun block and never walk in the sun with unprotected skin. The eyes are also susceptible to sunburn; always wear sunglasses. Always have the head and neck covered.
Tip: If you do not have sunglasses, improvise: (Make eye covering out of cardboard, paper or material (make only the smallest hole you can see through). To use Duct tape (fold a strip over, sticky side together and make narrow slots for your eyes, fix with string or more tape). Another possibility is to cut a thin strip of plastic foam from a seat in your abandoned vehicle and fix over the eyes (you will be able to see enough through it).Direct attack
Some risk exists from primitive tribesmen (depending on which part of the world you are in), who may place a different value on human life and see only the value of your possessions. People easily vanish without trace in the desert, so even if rescue seems at hand, always approach tribesmen with extreme caution, especially if you are unarmed.Indirect attack
Venomous snakes, scorpions and spiders pose the greatest risk. See above.Equipment
All electrical and mechanical equipment is susceptible to the desert dust and all equipment must be covered when not in use and cleaned regularly.Weapons
The same applies as with electrical equipment, all moving parts of any firearm need frequent cleaning, oiling and the weapon needs testing. Keep a condom over the end of a firearm's barrel. Optical sights, if fitted can soon deteriorate unless designed especially for desert use. Extreme temperatures can make metal parts of any weapon very hot to handle; keep all ammo in the coolest place possible.Visibility
Visibility can vary dramatically depending on radiated heat, the amount of dust in the air and just from the glare of the sun. Because of heat haze, judging distances can be a problem.Mirages and oasesThis is a mirage: The "water" and objects on the horizon do not actually exist.
The scientific explanation about how mirages are formed and the different types of mirages is fairly complex and outside the scope of this book. Simply put, desert mirages result from the heating of air overlying the hot sand. In a desert mirage, objects appear to be lower than they actually are. Also, the image is inverted and can appear to shimmer because of changes in refractive index (like a star twinkling).
The shining patch on the surface in the above photo is actually a reflection of the sky. The shimmering light looks like water because it is water we most want to see. It is not an hallucination, we are seeing an image of the sky but we want to interpret it as water. Mirages with palm trees and water are not uncommon, but this can be an image of an oasis that is many miles away. How can you tell it is a mirage? It changes if you view it from a lower angle. It shimmers. If you can see trees or buildings, they appear to be inverted. Oases
An oasis is formed by a pool of water trapped between layers of rock beneath the desert floor. The amount of water in a main oasis may be sufficient to permit people to settle near there and even grow crops. Most oases are often small, highly contaminated pools of water with some sparse surrounding vegetation. Often the water is so saline it is undrinkable and even from an oasis that is large and surrounded by lush vegetation, you should never drink the water without first filtering and purifying it because locals will water their animals there and these animals often pollute the water with their urine and faeces.
Uninhabited oases with date palms are rare. You must appreciate the trees have been planted and the fruit belongs to someone, so only take what you need and do nothing to damage the trees. If the oasis is inhabited or you happen upon nomadic tribesmen you must always ask permission to use the water or take fruit from the trees. Resources are fiercely protected. In all deserts, the main oases are mapped; if you don't have a map of the area, you are unlikely to find an oasis. In the worst-case scenario, find high ground and look for areas of greenery; washes look like thin green lines from a distance and you should be able to spot one of the larger oases if there is one in the area.
You may have to travel miles over burning sand only to find the green area has vegetation but no open source of water; in this case, all you can try is to dig down near the vegetation in an area where the topography is at its lowest point. Water can be very deep down. To determine if water is present, dig down one metre and place some dry material in the bottom of the hole. Several hours later, if the material is damp or better still wet, it is worth digging deeper because you have found water. Make several holes to determine the best place to expend your energy digging. If you find a pool that is contaminated and or saline, dig a hole one or two metres away and wait for it to fill with water, this water has effectively been through a sand filter as it flows from the oasis and the water in your hole will be much cleaner but possibly still saline.faunae
In a true survival situation, you should trap or look for lizards, tortoises, rodents, snakes, small mammals, such as the desert fox and remember that all insects are edible, so are scorpions. Rodents and lizards can be found by turning over small stones (Always use a stick, never your hands) and look in any area that is in shade.
Travelling by vehicle
Terrain, topography and climate that deserts encompass can vary greatly. Gravel plains, sand dunes, sand sheets, low rounded hills, harsh rocky landscapes, mountains, stony plains, boulder-strewn out wash fans as well as endless nondescript vistas of tough grass tussocks all offer different obstacles and challenges to travel by vehicle.Problems for vehicles
Surface roughness, surface unevenness and surface strength will be the main problems for vehicles. Stones and rocks, often with sharp edges or large rounded shapes, will demand careful, sympathetic driving and tyres inflated to the maximum. The unevenness of tracks — undulations or sudden potholes or, worst of all, the widely encountered transverse corrugations — will call for sensitive control of speed and usually an "on-off tracks" tyre pressure tied to a moderate upper speed limit. Typically this might be 1.8 bar and 64 km/h (40 mph) for a light 4 X 4 such as a Land Rover Defender 90.
Corrugations in the sand will demand a "harmonic speed" (probably 40 - 56 km/h (25 - 35 mph, which reduces the apparent effect of these features, but they will still be giving the suspension a pounding and at the same time make braking and steering far less effective than on normal desert tracks.
Reduced surface strength presents as soft sand on dunes, in wadis, on cut-up tracks, or unpredictable patches on sand plains. Here tyre pressures may well have to be reduced to 1.5 bar or even less to enlarge the tyre footprint and benefit flotation, but must be accompanied by speed reduction to 24 – 32 km/h 15 – 20 mph) — less if extreme deflation down to 1 bar is used. Reinflation must follow as soon as possible after the bad patches are covered. Failure to do so will cause tyre overheating with delamination, and will destroy covers; remember that this could be all four at once. Check the onroad tracks (64 km/h (40 mph) maximum) and emergency soft (24 km/h (15 mph) maximum) pressures for the tyres on your vehicle.
If you are taking a vehicle into the desert there is a critical rule
, which is payload, versus range and time, versus water
. The payload of the vehicle is its weight plus total cargo. The range of the vehicle is the amount of fuel needed to make the journey when fully laden plus 20%. Time is the estimated journey time, plus a 20% contingency figure and water is estimated at 3.8 litres (1 US gallon) of water per person per day. In fuel and water alone, you are carrying a lot of extra weight and this will reduce the range of the vehicle. If you use air-conditioning, this will dramatically increase fuel consumption. Do not rely on the manufacturer's data, for all these values, always make a few practice runs and learn how your vehicle can perform. Critical rule number two
is never travel with just one vehicle, a convoy of two is the minimum, especially if you intend to drive off the desert highways. Vehicle recovery charges in remote desert locations can cost thousands of dollars and the cost ramps up if you need rescue from a remote, off road location. The vehicle
No standard production vehicle is correctly equipped for travel in the desert. The basic vehicle has to have four wheel drive and a gearbox equipped with low ratio gears. Moving parts on the vehicle need protection from dust and sand. The vehicle needs a special air filter. An open topped vehicle is not suitable.
A long wheelbase Land Rover or Toyota Landcruiser are examples of vehicles that can be more easily modified for desert terrain than most of their rivals. For one thing, spare parts for these vehicles are often obtainable in obscure parts of the world because the locals use them. If you take a Humvee, for example, parts may be a problem unless there is an American military base nearby. If you intend to make a desert trip (perhaps the adventure of a lifetime), you would be best served by having a specialist company modify your vehicle, but as a minimum you need to consider the following:Sand and dust protection
Carburettors, fuel inlets, air and oil filters need to be specially adapted to cope with sand and dust in the desert. All air intakes need dust filters fitted over them. All exposed bearing must be protected against sand entering them.Suspension and bearings
Suspension needs to be "ruggedized" to cope with the extreme terrain. Sump protection
You must have a strong plate to protect the oil sump and the bottom of your vehicle against scraping by rocks.Batteries
You need to have a performance battery like the NATO-block battery. These dual-purpose, heavy-duty gel batteries can cope with deep current cycles as well as instant high currents. Such batteries are rated between 125 and 200Ah and you will never be stranded without enough power to start the vehicle. Unfortunately, most suppliers retailing batteries are hopeless when it comes to special applications like these, so you need to know what you want. Sonnenschein Dryfit batteries are a good choice (available through Exide). If you use an electric winch, you need one of these batteries.Winches
Definitely unsuitable are cheap winches in the price region of 200-300 pounds sterling. If you decide to fit a winch, the straight line pull should be around double the laden weight of your vehicle or greater. Remember to buy some ground anchors.Tyres
Radial tyres are always better than cross-ply tyres in desert terrain. Choose tyres for the sturdiness of their sidewalls and their ability to run at very low pressures for
extended periods; a good example is the Michelin XS (photo right) or XZL. If you want to use your tyres back home as well, a good compromise would be BF Goodrich AT or MT tyres, depending on your preference. Do not choose an overly aggressive tyre with tread patterns like the Goodyear Cargo G 90 tyre as this will dig into sand rather than pass over it. Tubeless tyres are better than tyres with inner tubes as they cope better with low pressures. The best advice for desert driving is to fit the largest and widest tyres your vehicle can take without making any major modifications. Carry a minimum of two full-sized spare wheels or two spare tyres (if you have the skill to fit them) and a puncture repair kit. An electrical air tyre inflator/compressor
is a vital piece of kit because you will have to reduce tyre pressure to travel over softer sand (gives a larger surface area of tread) and re-inflate the tyres to full working pressure when on more compact surfaces.Recovery equipment
For ropes and shackles, use only high quality, rated material. Inferior quality recovery equipment can be highly dangerous and cause serious injury. Rated shackles have a blue or green painted pin and should have a strength of at least 6 tons (6.09 tonnes), which also goes for ropes. A recovery rope for the desert should be around 10 metres (33 feet) long. You might prefer the more fancy Kinetic ropes, but bear in mind that you only get about 30 to 40 kinetic pulls out of one before it
degrades to an ordinary rope. Use a heavy-duty shovel
with a wide, (ideally) pointed blade. Army surplus stores have "pioneer" shovels that are strong and durable. A lightweight option is made by Fiskars, Scandinavia. A good tip is to carry a shovel for every member of the expedition; they are also useful for digging latrines.Sand plates (sand ladders or Waffles)
(See above photo showing sand plates carried on the Land Rover's roof rack.) Alloy sand plates are light but bend easily. Military sand plates made of steel are cheap but heavy. Kevlar sand plates are light, durable but very expensive. 4Technique's sand ladders are made from an alloy-steel compound; they weigh around 3 kilos (6.6 pounds) each, are solid and can also double up as a ladder for your roof rack. (Distributed in Europe by Taubenreuther.) Roof racks
Roof racks free up valuable space inside the vehicle. Ideally, choose a model that supports the weight over the full length of the gutter and travels the full length of the vehicle. Fit chequer plates to the wing and the bonnet so you can climb onto the roof rack, or fit a ladder to the rear of your vehicle. Cover the loaded roof rack with a white tarpaulin (white reflects more heat) to keep sand down, but do not store anything on the roof rack that can be damaged by heat, it will get hot up there. You can fit up the roof rack so you can sleep on top of the vehicle at night. Do not load your roof rack up so much the vehicle becomes top heavy.
Consider also having a tropical roof fitted to your vehicle. This is a second roof mounted on top of the vehicle's roof with an air gap between the two. This will lower the temperature inside the vehicle.
If you don't fit a tropical roof, paint the outside of the vehicle's roof white and line inside with insulation.Fuel
Military type "jerrycans" are most suitable for fuel. Make sure the rubber seal is in perfect condition if buying second-hand cans and take a spare seal or two if in doubt. When you purchase jerrycans, check the manufacturers stamp and batch number on the side or base of the can - cheap imports are around that only last a couple of days under severe conditions. For pouring fuel or water you will need a nozzle - always take one with a ventilation pipe otherwise it takes as long as ten minutes to empty a 20 litre (5.3 US gallons) can.Water
The most reliable water containers are Army-type containers; they are strong but lack a tap for convenient operation, although, many models of electric or hand pumps are available. Avoid second-hand containers, as you do not know what they have been filled with previously. Consider fitting a water tank into the vehicle, it keeps the water cooler, you can't lose it and it is faster to fill. Land Rover makes a 50-litre (13 US gallons) stainless steel water tank that fits in the vehicle's foot well. Carry a portable water pump, filtration system and water sterilizing equipment with you so you can fill up from any potentially potable water you find along the way.Other kit
1. Full tool kit, vehicle maintenance handbook, supplementary tools (such as clamps, files, wire, etc.), the spare parts' kit supplied by the car manufacturer and jumper leads.
2. Spare tyre/s, battery driven tyre pump, tyre levers, tyre repair kit, hydraulic jack, jack handle extension and a large base plate for jack.
3. Spare fuel can/s, spare water container/s and cool bags. For those going off the black top roads other items to include are:
4. Foot tyre pump, heavy-duty hydraulic or air jack, power winch, sand plates, safety rockets, comprehensive first aid kit and a radio-telephone where permitted. Renting a satellite phone is a good investment, you can almost always get a connection and there is the added bonus that the satellite phone provider can get an accurate fix on your location.
5. Emergency rations kit/s, matches and cooking stove.
6. Maps, compasses, latest road information, long-term weather forecast and guides to navigation by the sun and stars. Further advice
Do not speed across open, flat desert in case the surface changes without warning and your vehicle beds deeply into soft sand or a gully; at speed you will create a sandstorm that blinds others travelling behind you in your convoy. Well maintained corrugated road surfaces can be driven at modest pace but rocky surfaces should be treated with great care to prevent heavy wear on tyres. Sand seas are a challenge for drivers and require a cautious approach; ensure that your navigation lines are clear so that weaving between dunes does not cause disorientation.
Especially in windy conditions, it is possible to lose one's line of sight, leaving crews with little knowledge of where they are. If cresting dunes from dip slope to scarp, one needs to take great care that the vehicle does not either bog down or overturn. Keep off salt flats after rain and floods, especially in the winter and spring, when water tables can rise and make the going hazardous in soft mud. Beware of approaching traffic even when on marked and maintained tracks. If driving in a sandstorm, have all lights on, better still, get off the road and wait for the visibility to improve.
The desert is unforgiving to both man and vehicle. Make the schedule of your journey known in advance to friends or embassy/consulate officials who will actively check on your arrival at stated points. Breakdowns and multiple punctures are the most frequent problem. On the highway, the likelihood is always that a passing motorist will give assistance or a lift to the nearest control post or village. However, be aware that there are instances of highway robbery, you may get a lift, end up being dumped in the middle of nowhere and ultimately find your vehicle or possessions have vanished. For this reason, it is best for someone to stay with an abandoned vehicle and for only one person to go with the person assisting you.
Off road, breakdowns, punctures and bogging down in soft sand are the main difficulties. If you have left your travel program at your last stop, you will already have a fall-back position in case of severe problems. If you cannot make a repair, or free a stuck vehicle, remain with your vehicle in all circumstances. Unless you can clearly see a settlement (not a mirage), it is safer to stay where you are with water, food and shelter. The second vehicle can be used to search for help, but only after defining the precise location of the stuck vehicle; GPS is excellent for this.
If your party gets lost, stop up to conserve fuel while you attempt to get a bearing on either the topography or the planets/stars and work out a traverse to bring you back to a known line, such as, a highway, mountain ridge or coastline. If that fails, take up as prominent a position as possible to help rescue aircraft spot you. Attempt to find a local source of water by digging in the nearest wadi bed (Wash), collecting dew from the air at night, etc. If you have fuel to spare it can be used with great care both as a means of attracting attention and a way of boiling untreated water. If you are in a real predicament, set light to one of your spare tyres, this will send dense black smoke high in the air and there is a good chance this will be spotted. If you get into trouble in the desert, be patient, conserve energy and take the time you need to think things through.