Loading your van to avoid trailer sway

Is that a dog wagging its tail, or being wagged by the tail? We’ve all seen it. You’ve probably even taken action to distance yourself and your family from it… the swaying caravan.

Before we start throwing blame and relocating the cast iron cookware, let’s acknowledge that there can be a multitude of reasons that the van, boat or horse float in front of you is ‘all over the road’. And many of the reasons (such as fitting an extraordinarily long hitch to poke out past a long tray on a ute), will have not much to do with how the owner of the van loaded it. That said, let’s discuss how we can manage the weight distribution in a trailer to help ensure a memorable and repeatable family adventure for your next long weekend.

Your caravan having a little side lean or being slightly unsettled by a passing road train isn’t what we’re talking about here. It’s reasonable to expect that your van will move around a little, even on the finest of sealed roads. Add unlevel or irregular surfaces to the equation, and we’ll see lots more movement. Even in a van loaded by Archimedes himself.

Speaking of equations

Momentum is Mass times Velocity… the more mass, the more momentum at whatever speed in whichever direction. Reducing the mass of the objects in the van is just always a good idea. So maybe instead of moving the cast iron cookware you haven’t used in three years to the front or back, consider moving it to the shed and leaving it behind.

It’s also worth having a think about the role played by partially full water tanks. If your tanks are properly baffled, then the movement of the water is slowed (not stopped), therefore reducing the velocity (and the momentum) of the moving water. Without baffles, a half-full 120-litre tank can see a lot of momentum generated. All that sideways momentum is what can turn a little dip to the side into a self-sustaining cycle.

Getting caught up in percentages

We often hear a seeming mandate that our trailer ball weight (the mass of the trailer being carried by the tow ball) must be 10%. While this is an excellent guide, it can lead to some drivers developing a false sense of safety by being preoccupied with meeting this target by shifting weight around the van. Simply moving a toolbox, battery, spare tyre, or all of the above, from the back to front, or front to back in pursuit of attaining a 10% figure neglects the fact that the placement of the weight has more nuance than just its effect on the Tow Ball Mass (TBM).

Low and in the middle

If you were to pile up all the stuff (obviously essential stuff) in your van, including the fixtures and the optional extras you added, next to the van and could get a measure of where all the weight is sitting, what would you find? Your galley is likely pretty central with its stove, fridge and cupboards. That’s an excellent start. How much gear is at the extremes, though? What’s in that big locker on the front? What lives in those crates pushed in under the bed at the back? Is it just pillows and blankets in the cupboards above the bed? The reality is, the more mass that’s at either end of your van, the more your vehicle will be affected by the beginning of trailer sway. Likewise, for gear that’s stored in the top closets (or on the roof).

Single or tandem

Well, yes, a tandem trailer does offer you some weight-carrying and distribution flexibility and advantages. But it must be remembered that for the best effect, the four tandem wheels must be sharing the load evenly (or as close as possible). Having the trailer nose-diving or tail dragging, will result in a less than effective distribution of load, potentially leading to unloading and loading of suspension from side to side.

You’ve likely seen pretty effective demos where a small-scale model with a trailer is seen running on a treadmill at various speeds. This simple visual is an excellent way to see the effect of the placement of weight on your trailer. This is a pretty easy concept to grab once portrayed in miniature in front of your eyes and should, at least, get you thinking about your set-up.

Five tips

• Carry less – less weight equals less dramas.
• Down low – mass closer to the chassis, rather than the roof.
• Centered – your trailer wants to carry its load on its own wheels, so putting your heaviest things closer to the axles helps this.
• Little bit forward – yes, aim for the 10% TBM, but don’t achieve this by moving weight to the extremes of your trailer.
• Know your numbers – there’s no point in guessing. Get your setup weighed professionally so you know what you are working with.

Dave is the Director of the Australian Offroad Academy. Specialists in the instruction offroad driving, recovery, towing for public, commercial and government clients in many locations across Australia. Visit www.4x4training.com.au to see how they can help you.