Tips on driving different types of terrain

The most common surface you will encounter whilst out green laning is probably mud.  With that in mind I will cover this type pf terrain first, before moving on to cover other surface types such as rocks, sand, water, hills and side slopes.

Driving through Mud
Mud can be described as wet, soft, earthy matter.  There are several types of it.  However they all have one thing in common, they are formed by a mixture of soil and water in a ratio that turns otherwise firm ground into a soft, slippery surface.

Mud appears in countless variations dependant on where you are at the time.  There is heavy clay, soft peat and gritty loam, shallow and deep, wet and sticky and they all result in loss of grip on the vehicle tyres, especially those vehicles that are not equipped with Mud terrain tyres.

If you have any doubts get out and have a look at what you’re dealing with.  A five-minute recce now could save you hours of recovery later.  If the route is clearly too difficult for the vehicles in the group, make a judgement call and turn around.  If however you feel it will be possible with care, follow the techniques outlined below to obtain the best from the vehicles.

Instruct your group to select low ratio (if you have not already done so) and for vehicles equipped with a centre-locking differential to engage that as well.  Tell them to close all the windows as mud will invariably fly everywhere and you don’t want it in the cab.  It is important to maintain forward momentum, drive as fast as is necessary, but as slowly as possible.  By that I mean fast enough to maintain forward momentum, without risking losing control or racing unnecessarily.  Second, third or even fourth gear should be used dependant on vehicle and gradient.  The reason for this is to minimise wheel spin, by reducing the available torque to the driving wheel, whilst maintaining enough power to keep the vehicle moving. 

Once the vehicle is underway it is generally not a good idea to attempt a gear change, as this will cause a lack of momentum.  Therefore select an appropriate gear that will allow you to complete the muddy section without the need to change gears.

Do not fight the vehicles chosen path.  It will find the path of least resistance, but over steering in the opposite direction can result in the vehicle veering off your chosen course.

You should avoid harsh acceleration and steering movements.  If your wheels begin to spin, then ease off the throttle slightly to allow them to regain some grip without slowing down and losing forward momentum.

Deeply rutted tracks will require significantly more momentum than would be required in shallow mud or ruts, which offers a lower resistance to movement.

For vehicles equipped with traction control, it is important to keep the engine revs fairly high as these systems rely on sensors detecting wheels rotating at a certain sped to operate effectively.

If the vehicles tyre treads fill up with mud they will in effect become slicks, offering little or no grip at all.  Spinning the tyres up will sometimes, but not always throw the mud out of the tread and allow the tyre to regain grip on the surface.  In really gloopy, sticky mud this is unlikely to work for anything other than Mud terrain tyres and even then it is not guaranteed.  If the tyres cannot bite down into the ground to find grip, it is going to prove difficult to maintain any momentum.

If you take the time to explain these principles to the group before you embark on a muddy section, everyone has a good idea of what is expected, what is likely to happen and more importantly why.

Driving through Ruts
rutsIt is essential that you get out of the vehicle and inspect the ruts before attempting to drive them.  Have you got enough ground clearance for all the vehicles in the group?  Land Rovers will not be able to drive through ruts made by a farm tractor for example.  You would simply ground the vehicle out on the high point in the centre and become hopelessly stuck.  The photo opposite shows a Discovery high centred on the front Differential housing.

If the ruts are water filled how deep is the water?  How much mud and silt is in the bottom?  Are they shallow at the start becoming deeper as you progress?  Could you cross them if you had to?  Look for tell tale signs of differentials grounding out, indicated by scrapes on the route surface.

If you ever attempt to cross ruts it should be done at an angle of 45 to 50 degrees.  This will allow one wheel at a time to pass through the ruts whilst the other three provide drive and forward momentum. Once again engage low box and diff lock if fitted, and use second or third gear dependent on the gradient.

 As with driving in the mud, momentum is the key here.  Try not to have to change gear during the rutted section as this will serve to decrease or even lose forward momentum altogether.

Once you are in a rut it is inevitable that you are going to remain there until the end of the rutted section.  Think of them as tram or train lines.  i.e. You are going to go where they take you.  Once you have started the drive through maintain speed and accelerate gently to keep the momentum up.

It is also imperative that you always know in which direction your front wheels are pointing.  The steering wheels if not in line with the ruts, will cause drag and increase the risk of losing momentum and stopping altogether.  Another risk of not knowing where your wheels are pointing is that when the ruts end, the vehicle will then steer in whatever direction the wheels are pointing in and you may not be expecting that!.

Driving through Water

waterWater, the off road drivers magnate!! Everybody enjoys driving through water, making waves, splashing about, it’s an itch every of road driver needs to scratch. It’s fun, impressive and challenging.

But beware!!  It is probably the most potentially dangerous of all the off road driving activities.  Unseen obstacles combined with an unknown depth of water and most vehicles abject hate of water in their electrical and mechanical parts make driving through water a real hazard.  Mistakes made whilst driving through water are often costly to repair and notoriously difficult to rectify.

However having said that, there are safe limits to which you can put your vehicle through water.  This will depend on many factors and the following is not an exhaustive list.

Most vehicles will be able to wade safely in a depth of water that is equal to the top of the vehicle wheel rims, if you are unsure about the vehicles capability check the manufacturer specifications regarding the maximum recommended wading depth.

Have you taken steps to waterproof the vehicle?  Fitting wading plugs where necessary will help to stop the ingress of water into mechanical parts.  Waterproofing the vehicle electrics are essential if you hope to cross water and survive without incident.  Will the carpets get wet?  Is the ECU (if fitted) on the floor?  Are there any oil leaks from the engine or transmission or axles?  Remember if oil can escape, then water can gain entry.  This is not a good idea!!

Before attempting to drive through any water the first step is to ascertain how deep it is and what the surface of the riverbed is made of.  It is wise to carry Wellington boots with you for this purpose.  However when the water is deeper than your boots, it is always better to walk through and get wet than attempt to drive through blind.  A wet body is sorted in minutes.  A change of clothes and footwear and a towel and the job is done.  An engine that has hydraulic seizure or a flooded ECU is however not a five minute job, even if you had the tools and the skills to fix them!!

So before attempting to cross any water check the following.

waterEnter the water slowly and gradually accelerate to form a bow wave in front of your vehicle.  This will help prevent the ingress of massive amounts of water into the engine bay.  The bow wave is most effective at about 8mph
The photograph opposite clearly shows a bow wave in action, keeping mass amounts of water from entering the engine bay via the grille.
Once you have formed a bow wave, maintain a constant speed and follow it.
If you are crossing moving water try to cross at an angle facing slightly upstream.  This will provide a smaller surface area and lessen the force of the water on the side of the vehicle helping to prevent the current taking the vehicle downstream.
DO NOT BE TEMPTED TO ATTEMPT A CROSSING OF FAST FLOWING WATER!!!!!!!  THERE IS A SEVERE RISK OF THE VEHICLE AND IT’S OCCUPANTS BEING SWEPT AWAY BY THE CURRENT.
Dry your brakes out before continuing on your journey.

 

 

Driving through Sand

Sand is similar in many ways to mud in so far as it requires a steady forward momentum to be maintained in order to make progress.  Generally you will need to drive at higher speeds through sand than you would need to for mud.  Wherever possible examine the route to determine how soft the sand is and also how compacted it is.  Soft wet sand will be much harder to negotiate than hard wet sand for example.  Dry loose sand will quickly move under your wheels and allow the vehicle to sink if you are not travelling fast enough.

Avoid harsh cornering, braking and acceleration whilst negotiating sandy soils.  The use of any of these methods will result in the wheels breaking the surface crust and begin to dig themselves in.  If the wheels do start to dig in stop driving immediately, otherwise you’ll be extricating yourself from a very deep hole.  Reverse out if you can and find another route or try again with more momentum.  When you do become stuck its time to get out the shovel and the sand ladders and start digging.  Towing a vehicle stuck in the sand is likely to get the towing vehicle stuck as well, unless that vehicle is on firm ground or has sand waffles to spread the load and keep it’s wheels from breaking the surface crust.

When driving on open areas of sand you should try to maintain the highest safe speed possible.  There may be no need to engage low box if you can maintain enough speed and momentum in high range.  However it is wise to engage the centre-locking differential, if you have one, to ensure that the drive is equally distributed to both axles.   You should aim to keep the engine revs between 2000 and 3000RPM.  This gives you the best chance to maintain enough power to keep moving forward.  Be prepared to throttle back quickly if the wheels start to dig in.  The faster a wheel is spinning when it does so the deeper it goes and the quicker it does it.  Vehicles equipped with traction control have a slight advantage on sand, but remember traction control only works when it senses a wheel slipping, so be careful.  If you are venturing out onto beaches and other open areas never go alone. Sand tyres are essential for driving in the dessert, for other areas Mud and all-terrain type tyres work in much the same way as sand tyres do.

Personally I have found all terrain type tyres best suited to sand in the UK, as they do not have such an aggressive tread pattern as MT’s and are less likely to dig into the sand surface.

 

Driving over Rocks

Rock crawling is not the most likely thing you expect to do in the UK with your Land Rover, however in certain areas of the country there are plenty of exposed rocks that you are allowed to drive over.  Wales is a good example as are the Peak district in Derbyshire and parts of Northern England.

Always walk rocky sections before you drive them.  Look for a route that is compatible with the approach and departure angles and the ramp break over angle of your vehicles.  Do not be tempted to lower your tyre pressures for rock driving.  Whilst it is true that you may find more grip it also true that you are very likely to damage the sidewalls of your tyres when driving over rocky terrain.  The tyres will also be much more susceptible to damage form sharp edges and jagged rocks.  Try to find a route that avoids excessive axle travel, as this will induce wheel spin.  Engage low box and the centre diff lock, if you have one, and travel slowly and deliberately picking your way over the rocks using the best route.  It is often wise to get your passenger, or other drivers within the group to get out and guide you along the course.  Remember that the rear wheels will almost never follow the path of the front wheels and you should bear this in mind when route planning.  Failure to do this could result in an axle twister ( i.e where two diagonally opposite wheels both lose contact with the ground simultaneously.) resulting in loss of traction and forward momentum.

Use the lowest gear possible and drive slowly and carefully.  Watch out for areas that may cause damage to the underside of your vehicle.  Differential casings and steering components are easily damaged if care is not taken.  Pay special attention to the vehicles side sills.  Unless you have strengthened sill bars fitted it is very possible that you will re-design your vehicles sills when negotiating very undulating rocky surfaces.


Driving in Snow

snowWe don’t get that much snow here in the UK and frankly with most drivers here it shows.  I estimate that eighty per cent of the population are incapable of driving properly on snowy surfaces.  Land Rovers and 4x4’s in general will cope with snow better than most cars will, however you still have to know what you’re doing with them as they are also heavier and take a bit more stopping!

Don’t assume that because you’ve bought a 4x4 you are invincible, cos you’re not!!  That is a dangerous attitude to adopt and unfortunately one I come across all too often talking to 4x4 drivers generally.  Never venture out in the snow without some emergency supplies with you.  If you don’t need them yourself, there is every chance you will come across someone who will need them.  Remember the M11 fiasco back in 2003, when literally hundreds were trapped in their cars with no food, water, warm clothing etc.
The road was blocked with no way to escape or to fetch in help for that matter, how would your 4x4 have helped you then?

 

A survival blanket, change of clothes, warm drink(s) in vacuum flasks or even the little camping cooker, some water, tea, coffee, and milk would have been useful then wouldn’t it?
Useful items to carry in the winter months are; -  Shovel, sleeping bags or blankets, fresh water, tea or coffee, sugar, milk (powder), some biscuits, your mobile phone and it’s in car charger, jump leads, Wellington boots and a spare change of dry warm clothing.

In other words ask yourself the question “If you became stranded overnight in the snow somewhere, would you have enough on board supplies to prevent the onset of hypothermia and survive the winter’s night until rescue came the next day?”  If the answer is no, then do something about it before you leave home!!

Fresh snow is considerably easier to drive than hard packed snow will be.  Hard packed snow has been compressed by other vehicles into a surface resembling your local ice rink.  Fresh snow offers far more grip and is therefore more predictable and easier to drive on.  However even a layer of fresh snow can conceal a layer of ice underneath it.  When driving in snow select the highest gear possible to maintain a steady slow progress along the surface.  When moving off use the highest gear possible to help minimise wheel spin and select the centre-locking differential, if you have one, to prevent the axles driving at different speeds.  Keep braking to an absolute minimum and avoid harsh applications of the brakes.  Conversely the steering movements also need to be smooth kept to a minimum and avoid harsh steering movements.   Allow up to ten times the stopping distance requires for normal driving conditions.

If your wheels do start to spin, ease off the throttle a little to help the tyre regain some traction.  If forward momentum is lost completely try reversing back to a point that you know you can re-start from and try again with a little more speed.  Be careful though as speed is dangerous if you find you need to stop or change direction suddenly.  In the worst-case scenario you will have to turn back and find an alternate route.

 

Driving on Grass

Grass is probably the most unpredictable surface there is to drive across.  When it is dry it is usually a very good surface to drive over as it offers plenty of grip.  However, when wet it can be treacherous to drive over due to the changing characteristics of the surface when wet.  It can be as slippery as ice at times.  Fresh grass can change very quickly when it has become wet from a surface offering lots of grip to that of a very slippery one.  Treat grass much as you would do for mud.  Drive it slowly and carefully in second or third gear to help minimise wheel spin.  Use the steering, brakes and throttle with care at all times trying to avoid wheel spin.  Grassy hills and inclines are best avoided when wet and slippery, as the possibility of sliding out of control is just too dangerous to risk.

Don’t drive too fast through long grass as it could be concealing hidden dangers, such as rocks, holes or tree stumps and if you hit an obstacle like this at speed there is a real danger of losing control or worse still, breaking something.  Dry grass also contains lots of seeds and pollen, which will end up clogging up your radiator and intercooler.  Clear them regularly to prevent overheating.  Be careful when driving over tinder dry grass too.  Hot exhausts can cause serious fires in dry grassland areas and if the only way out is the way you came in, the fire extinguishers may be working overtime!!