Driving in floods

Firstly, it’s important to note that driving through a flood can be very damaging to your car, terminal even. Secondly, there is a very real possibility of being killed if you get it wrong – people die every year doing this. So, perhaps it’s better to find another route don’t you think? If you’re not phased by this warning, by all means read on… Or read this special guide to wading for those lucky enough to own a 4×4

The boring recce & preparation bit

So, it pouring with rain outside, it’s late, and you desperately need to get to your mum’s house so she can wash your pants. But then you turn a corner and the road is completely covered by water. Before diving in heroically, it’s best to check a few things. A. First, mentally note how similar a car is in design to a boat.

A boat

In fact, the best vehicle for floods is the penny farthing, which isn’t at all boat like. Look at these two nice chaps having a wonderful time. Not at all phased by the weather.

Two penny farthings

A car is cleverly sealed from beneath to prevent water ingress and this means in a worryingly small amount of water it will become buoyant – you won’t be able to steer particularly well, and you’ll float in the direction of the current into the nearest tree or ditch. Eventually water will seep in and you’ll get your feet wet. 

As a very vague rule of thumb, if water is halfway up the wheel rim, there is a good risk of vehicular floatage. Your owner’s manual may or may not quote a maximum wading depth – heed this advice is you’re the advice taking type. B. Check for hidden obstacles. This may seem slightly impractical as it’s unlikely you have your fisherman trousers on, but this is quite important to do this if you don’t like high risk activities. Take a look, or better still get in there with a long stick and prod around – look for shopping trolleys, otters and most importantly missing drain covers – these can easily swallow a wheel and make it impossible to progress. If you don’t feel like getting wet, why not park up and watch somebody else attempt to drive through, if they disappear under the water tiptoe back to your car and turn around. C. Have a think about your car, especially the location of the air intake. Some cars are just not cut out for wading, but if you have an air intake which is nice and high you have a slightly better chance of success. If water is sucked into your engine, the pistons will try and compress it, but water cannot be compressed – it’s actually stronger than metal in this situation and it will break something very important in a catastrophic and noisy way. Sometimes the entire engine head can be blown off, or you can bend a con rod.

A bent connecting rod

D. Consider your position in the road. Surfaces are usually higher in the middle to aid drainage – drive here to give yourself the best chance of success. If the water is shallow enough for two cars to pass, time your run to avoid passing a car coming in the opposite direction – their bow wave can easily flood your engine and make you very angry. Avoid the edges of the road as it can be hard to detect where the ditches start. E. If the water is flowing, avoid it. It’s just too risky, it won’t work, you’ll regret it in the morning.

The fun driving bit

When attempting to drive into the flood and out of the other side, do the following:

1. Be slow. Walking pace or slower is usually ok. Use first gear, and if you need to slip the clutch to keep your speed down that’s fine. If the water gets deeper and a small wave forms in the front of your car this can help artificially lower the depth of the water in the engine bay, which isn’t a bad thing.
2. Don’t worry too much about water getting into the exhaust, this won’t happen as long as the engine is running. If you do stall due to driver error – make sure you restart as quickly as possible to avoid water being sucked up as the air in the exhaust cools. Concentrate on keeping a steady speed and maintaining momentum. If you stall for an unexpected reason water may already be in the engine, it’s up to you whether to try and restart but it could do more damage.
3. If the water gets deeper unexpectedly, you should have done a better recce!
4. Slow down as you reach the other side – you don’t want water coming back towards you and going over the bonnet.
5. Test your brakes if you’re feeling safety conscious, although they will usually be absolutely fine unless you’re in a Model T Ford. Modern discs work pretty well even under water.

If you’ve floated into a deep river and sunk

If you do find yourself sinking to the bottom of a pond – here’s a simple guide to escaping from your car unscaithed.

1. Undo your seatbelt. Surprising how many people forget to do this. Must be the impending doom.
2. Whether you like it or not, you’re going to get wet. You won’t be able to open the doors due to the water pressure. If you’re a cheapskate and bought a car without electric windows you’ve had the last laugh – roll them down smugly.
3. If you’re lucky enough to have a car with electric windows they probably won’t work any more – you need to smash the window somehow. You could use a tool like the one below, or punch through like a real hero. Once you’re under water even a hammer won’t help as you won’t be able to get the necessary speed up.
4. If you fail to break the window, water will fill up the car anyway. Calmly wait for it to be completely full, and take the time to remember how good your life has been so far. Once the car is completely full, you’ll be able to open the door and swim gently to the surface.

Image credits: Stock images provided by freedigitalphotos.net. The boat is by Dan, many thanks..