by PR, for AD4x4
This article follows on from an introductory article on how to tow a stuck vehicle: please read Towing Stucks first - http://www.ad4x4.com/club/viewtopic.php?f=1&t=7125
On level ground there's not much that can go wrong, but on the steep inclines of sand dunes the situation is different and some attention must be paid to simple laws of physics and vehicle weight displacement.
On the kind of angles that steep dunes offer, a 4x4 vehicle is safe when going straight up or down, that is, when the vehicle is perpendicular to the dune. You can climb as far up the steepest dune as you like, and reverse down in a straight line. And in 1st gear and low range you can descend a dune in safety when you drive straight down.
The problem is when the vehicle is sideways on an angle; that is, when it is off-camber, or parallel to the dune line. The vehicle is much less stable when the weight is on one side, and, to make things worse, sand on the lower side will give way, worsening the angle and blocking the wheels on the downhill side. The vehicle may tip over. It's usually a very slow roll and passengers with safety belts on are rarely injured - nothing compared to a roll off the highway. However, I'm sure you will agree it's best prevented.
So, driving straight up or down a dune is fine, but turning sideways or traversing a dune sideways is not.
You might see experienced drivers running up a dune and turning around and then screaming back down, leaving nice rainbow-shaped tracks. They can do so because they know the amount of momentum they must maintain to prevent a roll. And even then, they are consciously taking a considerable risk. If they misjudge, or if they hit a soft spot, or if there's a hidden hard ridge, and they're caught in the wrong spot, they might roll over, too.
If you are caught stuck sideways, do not panic and do not open the doors. Do not allow any person to walk or stand downhill from your car.
CLEAR THE DOWNHILL - DON'T STAND THERE!
Direct two trusty and hefty friends to add weight to the uphill side; they must of course jump off if the car starts rolling, but in the meantime, adding their weight will make a big difference in preventing a roll.
Digging sand away from the downhill wheels may seem a good option, but it just puts a person at risk, might worsen the angle, and sand will just run down and fill the sand that is removed - so don't do it.
There are a few possibilities for recovery, depending on the situation, but here on the internet I'll first mention the main, simple procedure.
1. Anchor car on uphill side
2. Clear any people/cars from downhill side
3. Attach tow strap to rear downhill corner (never uphill side, middle is iffy)
4. Very gently, and I mean very gently, pull stuck car so that the rear end moves downhill just 20cm - stop!
5. Stuck driver tries to reverse
6. If not free, repeat pull for another 20cm
7. When stuck driver can reverse down slowly, release the uphill anchors.
Attaching the tow strap to the front is more risky, since that's where the engine's weight is.
Whatever you do, do not pull hard!
Now, some possibilities:
When you are still moving, and you sense you are about to get stuck, immediately gun it and turn downhill. If you are not stuck parallel to the dune, this makes recovery much simpler.
When you come to a stop parallel on a sideslope, do not spin your wheels. It digs the downhill wheels in and worsens the rollover angle.
If you have a rear-wheel-drive car, there's a nice and easy technique to get out of a sidestuck. When you realize you are stuck, disengage 4x4, and reverse spinning the wheels. Since only the rear wheels turn, the sand will shift, and the rear will swing downhill. Then engage 4x4 and reverse down slowly.
If you have difflock, engage and try. The problem with self-recovery from a sidestuck is that all the weight is on the downhill wheels, so without difflocks the uphill wheels will spin uselessly while the downhill wheels won't get any power. Engaging difflock will force the downhill wheels to also turn, enhancing your chances of self-recovery.
So there you have it. Stuck on a sideslope deserves serious consideration for everyone's safety, and to avoid damage to your car.
PLEASE STAY SAFE - a moment of foolishness can become a lifetime of regret
Very Happy to be AD4x4 member 