If you have a high-clearance 4WD, it can extend your options considerably. However, no vehicle can make up for an inexperienced driver – so ensure that you are confident of your vehicle's capabilities before
you venture into the wilds with it. You really need extensive practice, with an expert on hand to advise you, before you'll have the first idea how to handle such a vehicle in difficult terrain. Finally, driving in convoy is an essential
precaution in the more remote areas, in case one vehicle gets stuck or breaks down. Some of the more relevant techniques include:
Driving in sand
If you start to lose traction in deep sand, then stop on the next piece of solid ground that you come to. Lower your tyre pressure until there is a distinct bulge in the tyre walls (having first made sure that you have the means to re-inflate them when you reach solid roads again). A lower pressure will help your traction greatly, but increase the wear on your tyres. Pump them up again before you drive on a hard surface at speed, or the tyres will be badly damaged.
Where there are clear, deep-rutted tracks in the sand, don't fight the steering wheel – just relax and let your vehicle steer itself. Driving in the cool of the morning is easier than later in the day because when sand is cool it compacts better and is firmer. (When hot, the pockets of air between the sand grains expand and the sand becomes looser.)
If you do get stuck, despite these precautions, don't panic. Don't just rev the engine and spin the wheels – you'll only dig deeper. Instead stop. Relax and assess the situation. Now dig shallow ramps in front of all the wheels, reinforcing them with pieces of wood, vegetation, stones, material or anything else which will give the wheels better traction. Lighten the vehicle load (passengers out) and push. Don't let the engine revs die as you engage your lowest ratio gear, and use the clutch to ensure that the wheels don't spin wildly and dig themselves further into the sand.
Sometimes rocking the vehicle backwards and forwards will build up momentum to break you free. This can be done by intermittently applying the clutch and/or by getting helpers who can push and pull the vehicle at the same frequency. Once the vehicle is moving, the golden rule of sand driving is to keep up the momentum: if you pause, you will sink and stop.
Driving in mud
This is difficult, though the theory is the same as for sand: keep going and don't stop. That said, even the most experienced drivers get stuck. Some areas of Namibia (like the omurambas in Khaudum National Park) have very fine soil known as 'black-cotton' soil, which can become totally impassable when wet.
Push-starting when stuck
If you are unlucky enough to need to push-start your vehicle whilst it is stuck in sand or mud, then there is a remedy. Raise up the drive wheels, and take off one of the tyres. Then wrap a length of rope around the hub and treat it like a spinning top: one person (or more) pulls the rope to make the axle spin, whilst the driver lifts the clutch, turns the ignition on, and engages a low gear to turn the engine over. This is a difficult equivalent of a push start, but it may be your only option.
Have your tyre pressure higher than normal and move very slowly. If necessary passengers should get out and guide you along the track to avoid scraping the undercarriage on the ground. This can be a very slow business, and is often the case in the highlands of the northern Kaokoveld.
The first thing to do is to stop and check the river. You must assess its depth, its substrate (type of riverbed) and its current flow; and determine the best route to drive across it. This is best done by wading across the river (whilst watching for hippos and crocodiles, if necessary). Beware of water that's too deep for your vehicle, or the very real possibility of being swept away by a fast current and a slippery substrate.
If everything is OK then select your lowest gear ratio and drive through the water at a slow but steady rate. Your vehicle's air intake must be above the level of the water to avoid your engine filling with water. It's not worth taking risks, so remember that a flooded river will often subside to much safer levels by the next morning.
If the engine has overheated then the only option is to stop and turn the engine off. Don't open the radiator cap to refill it until the radiator is no longer hot to the touch. Even then, keep the engine running and the water circulating, while you refill the radiator – otherwise you run the risk of cracking the hot metal by suddenly cooling it. Flicking droplets of water on to the outside of a running engine will cool it.
In areas of tall grass keep a close watch on the water temperature gauge. Grass stems and seeds will get caught in the radiator grill and block the flow of air, causing the engine to overheat and the grass to catch fire. You should stop and remove the grass seeds every few kilometres also, depending on the conditions.