Driving a 4WD
You want a high-clearance 4WD to get anywhere in Botswana that's away from the main arteries. 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 ideas and techniques include:
When and how to use 4WD
Firstly, read your vehicle's manual. All makes are different, and have their quirks, and so you must read the manual before you set off. Note especially that you should never drive in 4WD mode with fixed (or 'locked') differentials on tar roads. Doing this will cause permanent damage to the mechanics of your vehicle.
When you do encounter traction difficulties, stop when you can and put the vehicle into 4WD – usually setting the second 'small' gear-stick to '4WD high' is fine for most situations.
Now get out of the vehicle and check if the front two hubs of your vehicle have, at their centre, knobs to turn. (This is the case with many Toyotas, though some newer vehicles have 'automatic' hubs.) If so, you'll need to turn these to the 'lock' position – a fact forgotten by many novices that causes untold trouble for them, and endless smug amusement for old Africa hands.
When you're past the problem, using 2WD will lower your fuel consumption, though many will use 4WD the whole time that they're in the bush. Remember to re-set your hubs to 'free' before you drive on tar again.
Driving in sand
If you're in 4WD and are really struggling in deep sand, then stop on the next fairly solid area that you come to. Lower your tyre pressure until there is a small 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. That probably means using '4WD low' rather than '4WD high.' 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 the driver 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.
Grass seeds in the Kalahari
After the rains, the Kalahari's tracks are often knee-high in seeding grass. As your vehicle drives through, stems and especially seeds can build up in front of and inside the radiator, and get trapped in crevices underneath the chassis. This is a major problem in the less-visited areas of the Kalahari. It's at its worst March to June, after the rains, and in the areas of the Great Salt Pans, the CKGR, and the tracks around Tsodilo and the Aha Hills. The main tracks around Chobe and Moremi are used relatively frequently, and so have less dangerous.
This causes a real danger of overheating (see below) and fire. Firstly, the build-up of seeds and stems over the radiator insulates it. Thus, if you aren't watching your gauges, the engine's temperature can rocket. It will swiftly seize up and catch fire. Secondly, the grass build-up itself, if allowed to become too big, can catch fire due to its contact with the hot exhaust system underneath the vehicle.
There are several strategies to minimise these dangers; best apply them all. Firstly, before you set out, buy a few square metres of the tightly woven window- meshing gauze material used in the windows of safari tents. Fix one large panel of this on the vehicle's bull-bars, well in front of the radiator grill. Fix another much closer to it, but still outside of the engine compartment. Hopefully this will reduce vastly the number of seeds reaching your radiator.
Secondly, watch your vehicle's engine-temperature gauge like a hawk when you're travelling through areas of grassland.
Thirdly, stop every 10km or so (yes, really, that often) and check the radiator and the undercarriage for pockets of stems and seeds. Pay special attention to the hot areas of the exhaust pipe; you should not allow a build-up of flammable material there. Use a stick or piece of wire to clean these seeds and stems out before you set off.
If the engine has overheated then the only option is to stop and turn it off. Stop, have a drink under a tree, and let it cool. 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.
When driving away, switch off any air-con (as it puts more strain on the engine). Open your windows and turn your heater and fan full on. This may not seem pleasant in the midday heat – but it'll help to cool the engine. Keep watching that engine-temperature gauge.
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. A few areas of Botswana (the road from Rakops to the CKGR's main gate is legendary in this respect) have very fine soil known as 'black-cotton' soil, which becomes 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, there is a remedy. Raise up the drive wheels, and take off one of the tyres. You should have a hi-lift jack with you, and know how to use it.
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 very difficult equivalent of a push start, but it may be your only option.
There's not much of this in northern Botswana – but you will find some in the southeast. 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.
Crossing rivers and stretches of water
The first thing to do is to stop and check the river. You must assess its depth, the 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 (though in an area frequented by hippos and crocodiles this is not advisable). 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 riverbed.
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 may subside to safer levels by the next morning.