Australian Four-Wheel Driving

Australian Four-Wheel Driving

Hints and Tips

Water Crossings

Take Heed

Water crossings can be one of the most dangerous hazards for four-wheel drivers if not confronted with extreme caution. Plunging your vehicle into a river without knowing what lay ahead is not only foolhardy but plain bloody stupid and is putting the lives of everyone in the vehicle at risk. In this article I refer to the word "rivers", which could be narrow mountain streams or larger rivers.

The crossing could be shallow or as deep as your windows. Just because a track or road enters the crossing and exits at the other side does not mean that at that particular time while you are there, that crossing is safe.

The river may have even been a safe crossing four days ago when you last travelled that road, but rains up country may have swollen the river to a depth which is now unsafe. Drivers who are crossing a few rivers over a short period of time (hours or even days) may become complacent and come to grief when they least expect it.

Unless you have travelled that crossing before a number of times, and can easily recognise the nature of the crossing, you should stop and inspect it.

If you are not familiar with the crossing, you'll have to walk across it to check it out. If you can't walk across in it shorts, there is no way you'll be able to drive across it. Be very careful with fast flowing rivers while you walk across. It does not take much water to knock even a large man off his feet and send him tumbling along into deeper water which is usually found just down from a crossing. It is very easy to loose your footing on slippery, moss-covered rocks - it is extremely difficult to regain your footing in such circumstances as the water pushes you along. Don't kid yourself.

If unsure about the strength of the water and unsure of the nature of the crossing, it would be sensible to carry a lifeline with you as you cross. This could be a long rope or tow ropes - long enough of course to allow you to reach the other side of the river. Tie one end to the vehicle and loop the other under your arms. In extreme cases where the rope is not long enough, have a capable person holding the rope at length as he follows you across. Use common sense and don't attempt this where you feel unsafe or unsure of the crossing only to have both people in the middle of the river with no "safety net".

Look for the shallowest part of the crossing. This is usually on the down-stream side of the crossing, marked by a ripple line in the water if it's shallow enough.

Look for large rocks that could knock the differentials.

Look for large holes that a wheel could drop into to. If need be, move rock to fill in these holes or just drive around them.

If the crossing is already marked by poles, still check the crossing. Who put the markers there? Was it some good-intentioned and helpful 4WDer before you, or was it a pack of idiots who thought it would be fun to lure vehicles directly into a hazard instead of around one? If the markers are correctly placed, leave them there.

Check out the exit bank. Is it mud, clay or rocks? How much momentum will be required to get up the bank - will you need first gear or will second gear be okay? If the exit curves, walk up and check around the corner - there may be a bog hole waiting for you. If you're in a convoy, you'll have to move ahead to make room for those following to be able to climb the exit hill as well without other vehicles blocking the way.

If the crossing is potentially difficult, it may be wise to have a recovery plan thought out, and even ready. Have all your recovery gear easily accessible in case you need them. If the need is considered, have the recovery gear already setup - cables and tree-trunk protectors already in place, snatch blocks setup, etc. Having another vehicle standing by in case of emergency is good sense. If travelling in convoy thru difficult crossings, have the lead vehicle stand by over the river ready to winch or tow any vehicle that gets into difficulty. For wide crossings, having a vehicle at the entry side in readiness is also smart, particularly if another vehicle becomes stranded nearer the entry side than the exit side - it may be easier to winch or tow them back rather than forward, and then they can have another run at the crossing.

Using a snatch block, a vehicle on the entry bank can pull a vehicle across the river to the exit bank (the winching article demonstrates this).

Proceeding Onward

If you find a number of hazards in the crossing, such as boulders, holes, or where the crossing drops off sharply into deep water, it may be wise to have someone standing near these hazards when possible to "mark" the way for you. If it's not possible to have the hazards indicated by people, it would be wise to mark these hazards with an easily visible stick, maybe with a piece of cloth tied to the top. Embed the stick in the river bottom so that it does not float away.

For extremely risky crossings, in deeper water that is fast flowing, some extra precautions will be needed. The last thing you want, besides people getting drowned of course, is to have your vehicle floating off down the river, sinking slowly into the deeper water. If in doubt as to whether you'll make it across, a safety line for the vehicle will be needed. This is a cable anchored securely to a tree on each side of the river. The cable should be loose enough to allow a vehicle tied to it to manoeuvre across the river in the required direction(s). A chain is shackled to the vehicle and then the chain is shackled to the cable - the cable should be on the upstream side of the vehicle. If two chains can be used, one at the front of the vehicle and one at the rear, the better. The chain at the front should not be too long so that it is dragged under the front wheel.

For water of medium to deep depth, spray all the electrical components in the engine bay with WD40 / CRC or similar water-protection spray. Don't be a miser - give them a good spray. Shallow water should not reach these components, but if unsure spray anyway.

When crossing, you need to proceed at a moderate, steady pace. Don't go charging across and don't drive too slowly. The pace should be sufficient to create a bow wave in front of the vehicle. Drive too slowly and a bow wave is not created. Drive too fast and the vehicle's movement forward negates the effect of the bow wave and water will flood into the engine compartment, and if it's deep enough will wash over the bonnet. Watch a large ship as it cruises to see the effect of a bow wave. The bow wave effect causes a pressure-front at the ship's bow which pushes the water ahead and away from the bow. The effect also causes a depression in the water immediately to the sides of the ship's bow which is lower than the normal level of the water. Very slow moving ships or fast moving boats don't create the bow wave effect. The ship's bow wave effect is exactly the same when you cross the river, when driven at the correct speed. Water is pushed away from the bonnet and hence away from the engine compartment and you'll find that very little water enters the engine compartment, even when lower than the river level.

For a water depth that is above the bumper bar, you'll need to take an extra precaution to help the bow wave effect. At this depth of water, even when driving at the "correct speed", water will be pushed up and into the radiator area purely because the amount of water overcomes the bow wave. In this case, you'll need to cover the front of the car with a tarpaulin, tied at the top and bottom sides. You need to over the entire radiator area and any inlet holes. Open the bonnet and close the bonnet down onto the tarpaulin and tie the ropes under the bumper.

As an added precaution, and one which is probably more important that the tarpaulin, is the removal of the fan belt. Yes, it has to be done, so you'd better have brought the necessary tools. Think back to the ship - what propels it? A propeller of course (I knew you knew). What shape is the propeller? What shape is the radiator fan blade - the same. What material are fan blades made out of these days - plastic. When the water hits the fan blade, it acts like a propeller, but the plastic blade will warp under the pressure of the water and chews into your radiator core. You won't get far with a radiator with gaping holes it in - about 2 kms at a guess. I hope that river's near an auto accessory outlet!

If you're travelling in a convoy, the next vehicle waits until the preceding vehicle is safely across and up the exit bank. You don't want two, or more, vehicles negotiating a crossing (or any other hazard for that matter) at the same time. If the front vehicle comes to grief, the following vehicles are then forced to stop which is the last thing you want in a water crossing!

Low-range second gear will do. If you use first gear the wheels may start slipping. You'll need enough momentum to climb any steep bank that may be on the other side - if second gear won't get you up that bank then start the crossing in first gear.

If driving a manual gearbox, do not under any circumstances change gears (that is, depress the clutch) once in the water. Water will get into the gearbox and destroy the gears. Pick the gear you need - second or first - and stay in that gear. Automatic gearboxes do not suffer from this problem, so if second gear is selected and the vehicle drops down a gear automatically, don't worry. It's the clutch depression, not the gear change itself, that is the problem.

You need to maintain your momentum. You do not want to stop in the river at any time.

Once you are safely out of the crossing and up the exit bank you can not drive off without further precautions as per below.

Remove the tarpaulin if it's been put in place. Replace the fan belt and adjust for the correct tension. Check under the engine bay, under the vehicle body, as well as around the radiator area for any foregin objects, such as small branches, which may have become lodged.

Your brakes will now be drenched and their effectiveness dramatically reduced. You need to dry out the brakes. This is done by driving slowly with your foot gently on the brakes - the heat caused by the friction dries the brakes. Every now and then, over a few minutes, try a gentle stop and you'll soon notice the brakes functioning correctly again. Proceed with caution for another few minutes until they dry completely.

Of course, if you used a safety cable for the vehicle you will have to unhook and retrieve the cable.

You may elect to leave the marker poles you placed in the river where they are to help fellow 4WDers, but remember the advice concerning markers under the Take Heed heading above.

Extracting Your Vehicle

Ooh-oh, you didn't make it. Don't panic.

The first concern is to ensure the engine does not stall - keep it running at all costs. If the engine stops, water will flood up the exhaust and into the engine. In a manual gearbox, if you need to select neutral, don't depress the clutch, just very quickly slip the gear level into neutral. Remember what was said above about not changing gears?

Try to reverse out of the situation. With a manual gearbox, shift from neutral to reverse with the quickest clutch change in history, without stalling the vehicle.

If the vehicle stalls, shift immediately into neutral (without depressing the clutch) and attempt an engine start immediately. Don't pump the accelerator in frustration. Start it normally. Get the revs back and try to reverse as above or move forward again.

If the whole party is in the vehicle, people will need to get out to help with the recovery. Don't open the doors unless you're sure that water level is below the sills. Climb out of the window if necessary. For difficult crossings, capable persons should already be ready with tow gear in hand - just in case. Now's the time to wade in and hook up the vehicles.

If winching or towing is needed you'll be grateful about that advice in the connecting cables section about practicing connecting cables blindfolded (oh, you didn't practise that?). Now you're going to have to attach a cable to a tow point that's under water and most likely not visible.

For manual gearboxes, if you had to use the clutch, then you'll need to inspect the gearbox oil for water. Don't do a cursory inspection - what good is that? If water is found you'll need to get mechanical help to strip-down, clean, and re-build the gearbox before you do too many more kilometres.