I came across a bloke a couple of years ago in the Victorian High Country. He was stopped in the middle of the Crooked River with the water up to his door handles… and looking nervous. After a brief chat we rigged up a winch, plucked him out and helped him drain the water out of his Pajero. It turned out he’d followed none of the ‘rules’ of water crossings, or 4X4 prep in general. Stock HT tyres at road pressures, only enough provisions for a quick overnighter, next to no drinking water. Let’s just say he was a little green to off-road adventure. After plucking the sparkplugs from his petrol engine we cranked it over and a geyser of water shot 20 feet into the air. Luckily he hadn’t tried to restart it and buggered his con-rods…
Still, it highlighted the necessity for knowing how to safely tackle crossings. Old mate could have easily been up for a couple of thousand dollars in towing fees, and a few thousand more for a new engine. So if you’re new to this 4X4 game, or even if you haven’t navigated a crossing in a while, here’s what you need to know before diving in.
PICKING YOUR LINE
Line selection is the first and most crucial step when fronting up to just about every off-road obstacle. Rocks, dunes, bogholes – the difference between driving it like a boss and getting stuck can be the difference of a few inches to the left or right; and water crossings are no different, so take your time and get a good idea of where you want your wheels to be. In many cases, this’ll mean getting wet and walking the crossing first. You want to note where there are holes, and anything submerged (like large rocks and tree branches that are going to damage the underside of your 4X4). If it’s a complicated crossing, you can mark these obstacles with sticks driven into the riverbed.
If you’re up the northern end of the country, you do have to remain croc-aware. Some crossings simply shouldn’t be walked. Have a chat to any locals to find out if there are any tricky waterways up ahead and pay attention to the signs – they’re there for a reason. Always have the recovery gear at the ready too. 4WDs don’t belong underwater for long, and the quicker you can get it out the better.
KNOWING YOUR VEHICLE
Do you know what the wading depth of your 4X4 is; do you know if there are any electrics mounted low in the engine bay; are you familiar with where your air intake is? It’s probably a good idea to gather such info before tackling deep crossings. And don’t think that just because you have a snorkel you’re OK to get windscreen-deep without a worry. Some of them (cough – 70 Series ’Cruisers – cough) are not sealed at all, and are meant more to keep the air intake up and out of the dust rather than facilitate deep-water engine breathing. It’s definitely worth checking before you leave the driveway.
PROTECTION… NOT JUST FOR TINDER DATES
So what does your 4X4 need for water protection? The aforementioned snorkel is a great start as it’s designed to raise your air intake to windscreen level. But don’t assume this means that’s how deep you can go before you’ll get into strife. Almost all modern four-wheel drives have a gaggle of important electrical gear under the bonnet that will take being submerged in muddy water about as well as your Tinder date will take the realisation that you used a bit too much ‘artistic license’ with your profile pics. They’ll just stop talking to you, your vehicle will just stop… and probably cost a lot to get going again. Giving the electrics a coating of water-dispersant and letting them dry out again on the other side of the crossing can work wonders here.
I GOT A SNORKEL, I DON’T NEED A WATER BRA… RIGHT?
Wrong! Well, at least in some cases. Ever seen what an engine-driven fan does to a radiator? It’s messy, expensive and will call a halt to your trip. What happens is that the water flows into your engine bay, and your radiator fan does what it’s designed to do and starts acting as a big propeller; only instead of pulling air in through your radiator, it propels itself forward and into the core. You know that scene from ‘Indiana Jones’ where the boats are being lunched by that huge ship’s prop? Yep, pretty much the same thing happens under your bonnet.
For me, water bras are cheap insurance, not to mention that they will help you build a bigger bow wave (more on that in a sec). They essentially mean that your engine bay is almost completely protected from water ingress; and they will protect your winch and spotties from getting a dunking too. They’re mandatory if you don’t have a snorkel, and still a great idea to fit even if you do.
THE SCIENCE OF BOW WAVES
Try this experiment next time you’re in the bath, or doing the washing up. Move you hand through the water, keeping it flat so you’re pushing as much water as you can. Notice how the water level directly behind your hand is lower? The same principle applies when you’re driving your 4X4 through a creek. The front end pushes the water out of the way, leaving a depression right behind which (if you do it correctly) will have your engine in it. It effectively turns a four-foot deep crossing into a two-foot deep crossing – at least as far as your engine bay is concerned.
The trick is to keep a steady and constant speed. Too fast will see the water up over your bonnet; too slow will see the depression behind the bow wave fill up with water too quickly. The rule of thumb is to put it in second gear low range and drive in the fat part of your torque curve, not changing gears or speed too much until you hit the other side. Of course, things don’t always go to plan…
I DIDN’T MAKE IT, WHAT DO I DO?
If you come to a halt during a crossing, you’ll need to quickly assess the immediate threat to both your vehicle and the people on-board. This threat assessment will largely be based on the conditions such as how deep it is, what sort of base you’re driving on, whether current is a factor and what your options are for getting unstuck. For example, let’s say you contact a rock that you hadn’t spotted when you initially walked the crossing and it’s halted forward momentum. You’re in a shallow creek with little current and a firm sandy base. Very slowly back up a couple of feet, taking care not to push water up the exhaust pipe and back into the engine, and have a spotter direct you around the rock and on to safety. Simple.
Now let’s say you’re four-feet deep on an unclear crossing with a sticky mud base which has you bogged. Water is lapping at your window frames and the foot wells are starting to fill up. This is where you shut the engine off (unless there’s absolutely no chance of it copping a lungful of muddy water); and seeing how you’re a prepared four-wheel driver, you will already have your winch cable unspooled and coiled on the bonnet held down by some tape, or around your bull bar uprights. You get out, get the cable over to a pre-determined suitable anchor point that has been pre-wrapped with a tree trunk protector and effect your winch recovery. A few minutes from being bogged and potentially screwed, to being safe and in a position to assess any damage while you wait for your interior to drain.
NOT SO FAST THERE, TONTO
OK, so you’ve just driven a pretty serious crossing (like Nolan’s Brook) like a champ. You didn’t even look like getting stuck once. Beauty! Once you’re on the other side though, don’t just drive off. You didn’t just tour the Macca’s drive-thru here. You need to open your doors and let any water drain out of your vehicle and back into the waterway. You’ll also need to dry your brakes out. Have a couple of sharp accelerations followed by heavy braking, or lightly drag the brakes as you’re moving slowly forward. You want them to be working next time you need them.
Finally, give your under-bonnet a quick eyeball and make sure nothing important has copped a dousing. A follow-up spray of water-dispersant may be in order before continuing on your way.
FLOODWATERS – DON’T BE A KNOB
After the massive amount of rain we’ve had in this country over the last year or so, floodwaters deserve a mention. Put simply: Don’t try and cross them. They’re different to normal water crossings as there are a lot more variables involved, most of which you have no control over (or any way of knowing whether they’re even a factor). The water can appear to be completely still on the surface, but be moving fast enough to sweep you (and your vehicle) away a couple of feet down – so you can neither safely walk nor drive them.
Similarly, they could be covering a road that has had the base completely eroded. You may think you know what’s there, but when that 30cm-deep crossing suddenly becomes a couple of metres deep, you’ll quite literally be up the creek without a paddle… just a written off fourby and hopefully a means of escape. Don’t risk it, guys.