How to drive through water: Offroad driving techniques

Most serious four-wheel drivers with high skill levels love to make a splash through a river crossing. But water crossings can be unforgiving if things go wrong, potentially leaving you with a damaged vehicle and a red face … especially if you have onlookers lining the banks on the water’s edge.

There’s no doubt that river crossings make for great photos and social media posts — they can be one of the most exhilarating parts of a trip. Even if you’re tackling the same river you crossed a week earlier, you need to take all the same precautions, as you’ll seldom encounter the exact same conditions. Water depth and flow will differ, and the driving surface may have shifted too, depending on the number of vehicles which have since made the crossing.

Make sure you’ve got the right setup

Before you enter the water make sure everything is as well sealed as possible. It’s a good idea to check for any spots where water might enter the engine, such as a loose engine oil dipstick, and seal them as best you can. Door and window seals are also worth checking if you want to keep your feet dry.

A snorkel will dramatically improve your chances in deeper water by allowing your engine to breathe from higher up. Vehicles without snorkels draw air from low down and will instead inhale water in even a relatively shallow river crossing.

Diff breathers can help prevent water entering where it shouldn’t and are especially handy in hotter climates. When a hot diff is dunked in water and cools rapidly, sudden contractions cause water to be sucked through seals. Diff breathers provide an alternate path for air to enter so that water will stay out. A water bra is another worthy investment and a great way to prevent water spilling into your engine bay.

What to do before you enter the water

On reaching the water you intend to cross, it’s best to check it out for depth and submerged obstructions as the first thing you do by wading through — assuming it’s safe to do so. If you’re at the top end of Australia and close to the coast (especially in the Northern Territory, Tropical North Queensland or the Kimberley in Western Australia), you’d be wise to avoid wading rivers, so you don’t end up as dinner for a saltwater croc. If you have any doubt as to the strength of the current or other dangers, attach yourself to a firm anchor point as a lifeline to prevent being swept away. Be aware of undercurrents and any boulders, low spots or deep holes concealed beneath.

Once you’re comfortable with the depth, flow and bottom surface, check the entry and exit points, make sure they’re not too steep and the surfaces aren’t too loose, and be wary that if you can’t pick a straight line your turning circle may be reduced by water drag and surface inconsistencies.

If you’ve been on the road a while, it’s a good idea to let your engine cool before dipping it in. There are a number of reasons for this, which include the effectiveness of seals and rapid cooling of metals.

You also don’t want cooling fans running, as they can be damaged by the water. It’s wise to turn off your air-con so that it doesn’t suck in water. If you do get stuck in deep water, it might be tricky to access recovery points and the longer your vehicle sits there, the greater the chance of water seeping in and doing damage. Prior to entering, it’s a good idea to prepare recovery equipment, attach snatch straps and so forth, which will allow a speedy recovery.

A clean entry into the water

If the water is lower than your axles, then there’s no harm in making a bit of a splash and cruising through. Otherwise, take a few deep breaths, pop it into low range, engage diff lockers (if you have them) and ease it in. You’re looking to enter the water gently, to reduce splashing and produce a gentle bow wave that will push water away from your radiator, reducing resistance and preventing ingress. Stalling is to be avoided; it can allow water to get in where it shouldn’t, so you’ll want to pick one gear and stick with it. If you get stuck keep the engine running so that water doesn’t get drawn into the exhaust and creep in where it’s not wanted.

What to do once you’re in the water

Continue along your chosen line to the exit point at a steady pace and avoid changing gears. Fast currents may push you off course. You can combat this by steering gently into the flow. Use landmarks such as trees and boulders to maintain your course and keep your thumbs on the outside of the steering wheel (an unseen obstacle may cause the wheel to turn quickly and cause injury).

Once you climb the exit, pause as soon as it’s safe to do so to allow water to drain from your vehicle, so as not to make the following section of the vehicle track too muddy. If you’ve used a water bra, take it off so that your engine can cool, and as you drive on, apply brakes gently so that they can dry out evenly

Top tips for driving through water

• Walk the crossing before you drive it. If you can’t, then it’s advised you don’t proceed.
• For any depth greater than 1m, a snorkel and breathers are a must
• Enter gently and proceed steadily to form and retain a good bow wave
• If strong currents push you off course, correct by steering into them
• Use a low gear and don’t shift; try to avoid stalling.
• Attach recovery gear (shackles and snatch strap) before entering deep water

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