One of the most unnerving experiences in a 4WD is driving across a tidal flat. The thought that at any minute you could sink into a hole that you’d spend most of the day trying to get out of while the tide is rising is one that you don’t forget quickly.
We’ve been stuck in the edge of a salt lake down near Israelite Bay from a poor quality split second decision, and it isn’t fun.
I look back now and laugh about it, but at the time we were in a pretty serious predicament, and only just made it out without calling in extra resources. Fortunately for us there was no risk of a rising tide, but often there is.
Many people are not so lucky, and the number of 4WD’s that get caught in a rising tide is significant particularly in the northern parts of Australia where the tide can be 5 + metres tall.
How do you cross tidal flats?
The first, and most important thing to ask yourself is whether you actually need to get across, and whether you can find a different way. Driving on a tidal flat is always risky no matter how well prepared you are, and recoveries are difficult, and expensive.
You are almost always racing against the clock too, as once a tide comes up and your car gets wet, its even harder to recover and your insurance company will write it off on the spot anyway.
On that note, make sure your insurance is going to cover you if you do get stuck, and end up with a vehicle covered in salt water!
Stick to well used paths
If you are going to drive across a tidal flat, stick to the paths that are clearly marked, and that have been driven by 4WD’s before. You’ll find the moment you drive off those paths it can be a sticky mess, and over time these have been compacted and made the safest way to cross the flats. This was my exact experience at Israelite Bay.
Reduce your tyre pressures
It goes without saying that you should have your tyres down when crossing tidal flats. Somewhere around the 50% of normal highway tyre pressures is probably on the money, but it will depend on your setup, and how fast you are driving.
Less air in your tyres means better flotation, and that is the only thing stopping you ending up in the bottom of a muddy fest pool.
I’ve seen people end up in all sorts of trouble on tidal flats simply because they chose to drive through in 2WD. If you are going to cross a tidal flat, make sure you are in high range (or low range) with the centre diff lock engaged as applicable.
The extra traction might be the difference between you coming to a giant stop, or popping back up again and continuing on your merry way.
Avoid any wet areas
If you can see there are areas that are wet, avoid them. Don’t drive in a huge ark around them, but leave enough distance so you aren’t going into the same slop as everyone else.
At Pardoo Station, the only times we felt really uneasy was when you came across sloppy areas that you had to drive slightly around, and there was plenty of evidence of other cars who’d sunk down quite a bit!
Check when the last tide was
Its super important to check when the last tide was, and to seek local knowledge. Near Wyndham is a 4WD track that is popular, but it requires you to drive across a long tidal flat, that gets flooded every time there is a king tide.
Local knowledge says you should avoid the tidal flats for at least a week after the king tides, and that’s so the ground has enough time to dry up, and become hard enough to support a 3 tonne 4WD.
At Pardoo Station, they say at least 4 days, and preferably 6 days before driving across their tidal flats. The recovery fee at Pardoo starts at $750, and goes up from there depending on how badly you are stuck, and how quickly they can get to you.
It even states on their instructions that your vehicle may be left until they have time to recover you. In that case, one tide above your sill level, and your vehicle is basically a bin job anyway.
Maintain some momentum
You want to be rolling at a reasonable speed over tidal flats. Not so much that you can’t avoid holes, or anything unexpected, but not so slowly that if you do sink a bit you just stop immediately. Somewhere around the 30 – 40km/h is generally a good speed if its open, clear and wide.
Pay attention and take care
A moments inattention is all you need to end up in a world of pain. Watch what you are doing, take it easy and you’ll have the best chance of getting through without a problem.
Go with a second vehicle
Crossing tidal flats, or salt lakes without a second vehicle is a terrible idea. You should always have one that is on solid ground, and waiting until the other vehicle has made it through. If you get stuck out in a salt lake or tidal flat on your own, good luck getting out. It’s hard enough with a second vehicle, but at least you have more options.